Senior High School
NOT
General Biology 1
Quarter 1 - Module 1
Cell: the basic unit of life
Department of Education ● Republic of the Philippines
1
General Biology 1- Grade 12
Alternative Delivery Mode
Quarter 1 - Module 1: Cell: the basic unit of life
First Edition, 2020
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Senior
High
School
Senior
High
School
General Biology 1
Quarter 1 - Module 1:
Cell: the basic unit of life
This instructional material was collaboratively developed and reviewed
by educators from public schools. We encourage teachers and other
education stakeholders to email their feedback, comments, and
recommendations to the Department of Education at action@ deped.gov.ph.
We value your feedback and recommendations.
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Table of Contents
What This Module is About ....................................................................................................................... i
What I Need to Know .................................................................................................................................. ii
How to Learn from this Module............................................................................................................... ii
Icons of this Module ................................................................................................................................... iii
What I Know ................................................................................................................................................iii
First Quarter
Lesson 1: Cell Theory
What I Need to Know ..................................................................................................... 14
What‘s New: Guess What?.......................................................................................... 15
What Is It:
Learning Concepts ................................................................................. 16
What‘s More: Synthesizing Information .................................................................. 17
What‘s New: Reflection…. .......................................................................................... 18
What I Have Learned: ................................................................................................... 18
What I Can Do: Performance Task and Enrichment Activity ............................ 19
Lesson 2: Cell Structure and Functions
What I Need to Know ..................................................................................................... 20
What‘s New: .................................................................................................................... 21
What Is It: Learning Concepts .................................................................................... 23
What‘s More: ................................................................................................................... 24
What I Can Do: …………………………………….........................................25
Lesson 3: Prokaryotic vs Eukaryotic Cells
What I Need to Know ..................................................................................................... 26
What‘s New: .................................................................................................................... 26
What Is It: Learning Concepts .................................................................................... 27
What‘s More: ................................................................................................................... 28
What I Have Learned: .................................................................................................. 28
What I Can Do: …………………………………….........................................29
5
Lesson 4: Cell Types and Cell Modifications
What I Need to Know ..................................................................................................... 30
What‘s New: .................................................................................................................... 30
What Is It: Learning Concepts .................................................................................... 31
What‘s More: ................................................................................................................... 34
What I Have Learned: .................................................................................................. 34
What I Can Do: …………………………………….........................................34
Lesson 5: Cell Cycle
What I Need to Know ..................................................................................................... 35
What‘s New: .................................................................................................................... 35
What Is It: Learning Concepts .................................................................................... 36
What‘s More: ................................................................................................................... 40
What I Have Learned: .................................................................................................. 41
What I Can Do: …………………………………….........................................41
Summary…………………………………………………………………………………………….43
Assesment…………………………………………………………………………………………...44
Key to Answers…………………………………………………………………………………..….45
References ................................................................................................................................................. .. 52
Lesson 6: Transport Mechanisms
What I Need to Know ..................................................................................................... 54
6.1
Structural Components of the Cell Membrane
What I Know ..................................................................................................................... 55
What‘s In (REVIEW): .................................................................................................... 57
What‘s New: .................................................................................................................... 61
What Is It: ......................................................................................................................... 61
What‘s More: ................................................................................................................... 62
What I Have Learned: .................................................................................................. 62
What I Can Do: …………………………………….........................................63
6
6.2
The Relationship of the Structure and Composition of the Cell
Membrane to its Function
What I Know ..................................................................................................................... 63
What‘s In (REVIEW): .................................................................................................... 65
What‘s New: .................................................................................................................... 68
What Is It: ......................................................................................................................... 68
What‘s More: ................................................................................................................... 69
What I Have Learned: .................................................................................................. 69
What I Can Do: …………………………………….........................................69
6.3
6.4
Transport Mechanisms in Cells
Endocytosis vs. Exocytosis
What I Know ..................................................................................................................... 70
What‘s In (REVIEW): .................................................................................................... 72
What‘s New: .................................................................................................................... 81
What Is It: ......................................................................................................................... 81
What‘s More: ................................................................................................................... 81
What I Have Learned: .................................................................................................. 82
What I Can Do: …………………………………….........................................82
Assesment…………………………………………………………………………………………...83
Lesson 7: Structures and Functions of Biological MoleculesEnzymes
What I Need to Know..................................................................................................... 86
7.1
Description of the Components of Enzymes
What I Know ..................................................................................................................... 88
What‘s In (REVIEW): .................................................................................................... 89
What‘s New: .................................................................................................................... 92
What Is It: ......................................................................................................................... 92
What‘s More: ................................................................................................................... 93
What I Have Learned: .................................................................................................. 93
What I Can Do: …………………………………….........................................94
7
7.2
Oxidation/Reduction Reactions
What I Know ..................................................................................................................... 95
What‘s In (REVIEW): .................................................................................................... 95
What‘s New: .................................................................................................................... 97
What Is It: ......................................................................................................................... 97
What I Have Learned: .................................................................................................. 98
7.3
Determining the Factors Affecting Enzyme Activity
What I Know ..................................................................................................................... 99
What‘s In (REVIEW): .................................................................................................... 100
What‘s New: .................................................................................................................... 105
What Is It: ......................................................................................................................... 105
What I Have Learned: .................................................................................................. 105
What I Can Do: …………………………………….........................................106
Assessment: (Post-Test) ............................................................................................. ..106
Key to Answers......................................................................................................................................... .. 110
References ................................................................................................................................................. .. 112
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Module 1
Cell: the basic unit life
What This Module is About
This module demonstrates your understanding of the cell theory, cell structure
and functions, prokaryotic vs eukaryotic cells, cell types and modifications, cell cycle
and transport mechanisms which are the major topics of cellular biology. Learners
will be looking into the processes that are important to sustain life.
This module will help you explore the key concepts on topics and immersed
you in various activities and hands-on tasks that will help you answer the questions
pertaining to the cell theory, structure and functions, cell types and modifications, cell
cycle and transport mechanisms.
This module has seven (7) lessons:







Lesson 1- Cell Theory
Lesson 2- Cell Structure and Functions
Lesson 3- Prokaryotic vs Eukaryotic Cells
Lesson 4- Cell Types and Cell Modifications
Lesson 5- Cell Cycle
Lesson 6- Transport Mechanisms
Lesson 7- Structures and Functions of Biological Molecules-Enzymes
What I Need to Know
After going through this module, you are expected to:
1. Explain the postulates of the Cell Theory (STEM_BIO11/12-Ia-c-1).
2. Describe the structure and function of major and subcellular organelles
(STEM_BIO11/12-Ia-c-2).
3. Distinguish prokaryotic and eukaryotic cells according to their distinguishing
features (STEM_BIO11/12-Ia-c-3).
4. Classify different cell types (of plant/animal tissues) and specify the functions of
each (STEM_BIO11/12-Ia-c-4).
5. Describe some cell modifications that lead to adaptation to carry out specialized
functions (STEM_BIO11/12-Ia-c-5).
6. Characterize the phases
(STEM_BIO11/12-Id-f-6).
of
the cell
cycle
and
their
control
points
7. Describe the structural components of the cell membrane (STEM_BIO11/12-Ig-h11)
8. Relate the structure and composition of the cell membrane to its function
(STEM_BIO11/12-Ig-h-12)
10
9. Explain transport mechanisms in cells (diffusion osmosis, facilitated transport,
active transport) (STEM_BIO11/12-Ig-h-13).
10. Differentiate exocytosis and endocytosis (STEM_BIO11/12-Ig-h-14)
11. Describe the components of an enzyme (STEM_BIO11/12-Ii-j-17)
12. Explain oxidation/reduction reactions (STEM_BIO11/12-Ii-j-18)
13. Determine how factors such as pH, temperature, and substrate affect enzyme
activity (STEM_BIO11/12-Ii-j-19)
How to Learn from this Module
11
To achieve the learning competencies cited above, you are to do the following:
•
Take your time reading the lessons carefully.
•
Follow the directions and/or instructions in the activities and exercises diligently.
•
Answer all the given tests and exercises.
Icons of this Module
What I Need to
Know
This part contains learning objectives that
are set for you to learn as you go along the
module.
What I know
This is an assessment as to your level of
knowledge to the subject matter at hand,
meant specifically to gauge prior related
knowledge
This part connects previous lesson with that
of the current one.
What‘s In
What‘s New
An introduction of the new lesson through
various activities, before it will be presented
to you
What is It
These are discussions of the activities as a
way to deepen your discovery and understanding of the concept.
What‘s More
These are follow-up activities that are intended for you to practice further in order to
master the competencies.
What I Have
Learned
Activities designed to process what you
have learned from the lesson
What I can do
These are tasks that are designed to showcase your skills and knowledge gained, and
applied into real-life concerns and situations.
II
What I Know
12
MULTIPLE CHOICE:
Directions: Read and understand each item and choose the letter of the correct answer.
Write your answers on a separate sheet of paper.
__1. Which level of organization is the basic unit of life?
A. Cell
B. Tissue
C. Organ
D. System
__2. Which of the following is NOT a postulate of a unified cell theory?
A. All living things are composed of cells
B. Cells are the basic unit of life
C. All cells undergo complete development
D. All new cells arise from existing cells
__3. Who coined the term cell for the box like structure he observed when viewing cork
tissue?
A. Matthias Schleiden
B. Theodor Schwann
C. Rudolf Virchow
D. Robert Hooke
__4. In many cells, the structure that controls the cell activities is the _____________.
A. Cell Membrane
B. Organelle
C. Nucleolus
D. Nucleus
__5. Which part of the cell serves as venue for cellular respiration and is known as the
powerhouse of the cell?
A. Nucleolus
B. Chromosome
C. Mitochondrion
D. Nucleus
__6. Which type of tissue would be found in the epidermis and form the lining of internal
organs such as the intestines?
A. Nervous tissue
B. Muscular tissue
C. Connective tissue
D. Epithelial tissue
__7. The process by which the nucleus divides to produce two new nuclei that results in two
daughter cells that are genetically identical to each other and to the parental cell from which
they came.
A. Meiosis
B. Interphase
C. Mitosis
D. Cytokinesis
__8. A type of passive transport which relies on carrier proteins in order for the substances
to move down their concentration gradient.
A. Active transport
B. Facilitated diffusion
C. Osmosis
D. Sodium-potassium pump
__9. Which of the following is an example of passive transport which occurs when particles
move from an area of higher concentration to an area of lower concentration?
A. Phagocytosis
B. Pinocytosis
13
C. Diffusion
D. Osmosis
__10. This process utilizes additional metabolic energy against the concentration gradient to
move molecules across the membrane from a region of lower concentration to a region of
higher concentration.
A. Active Transport
B. Passive Transport
C. Osmosis
D. Exocytosis
14
Lesson
1
The Cell Theory
What I Need to Know
Cells are the basic building blocks of all living things. The human body is
composed of trillions of cells. They provide structure for the body, take in nutrients
from food, convert those nutrients into energy, and carry out specialized functions.
Cells also contain the body’s hereditary material and can make copies of
themselves.
Cells have many parts, each with a different function. Some of these
parts, called organelles, are specialized structures that perform certain tasks within
the cell.
In this lesson, you are to explain the postulates of the cell theory. The
three postulates of the cell theory offer the basis on how an organism is considered
as a living thing.
Plant cell
Animal cell
15
What’s New
Guess What?
Direction: Complete the three basic components of the cell theory by arranging these
words in proper order. All your answers must be written on a separate sheet of
paper.
1. LIVING OF CELLS OR ONE ALL MORE THINGS
COMPOSED ARE
2. IS UNIT THE BASIC CELL LIFE OF THE
3. FROM ARISE CELLS PRE-EXISTING CELLS ALL
16
What Is It
Prior to the invention of the very first microscope, everything that could not
be seen by the naked eye was unexplainable. In 1665, English physicist Robert
Hooke used of the first light microscopes to look at thin slices of plant tissues. One of
these, a slice of cork, especially caught his eye. Under the microscope, cork seemed
to be made of thousands of tiny chambers. Hooke called this chambers ―cells‖
because they reminded him of a monastery‘s tiny rooms, which were also known as
cells. Until 1676, Anton van Leeuwenhoek published his observations on tiny living
organisms which he named animalcules. It was believed that Leeuwenhoek was the
first to observe under his microscope the structure of a red blood cell of different
animals as well as a sperm cell.
One of the leading botanists in his time, Robert Brown in 1831 was able to
compare diverse kinds of plant specimens under the microscope. He markedly
indicated that there is a common thing about them-they are all composed of cells,
and inside the cell is a dark dense spot which he termed as the nucleus. A few years
later, German botanist Matthias Schleiden (1838) concluded that all plant parts are
made of cells. Theodor Schwann (1839), also a botanist and a close friend of
Schleiden, stated that all animal tissues are composed of cells, too. In 1858, Rudolf
Virchow concluded that all cells come from pre-existing cells.
Figure 1.1. Structure of cork using a microscope as seen by Robert Hooke (1665)
17
The discoveries made by Hooke, Leeuwenhoek, Schleiden, Schwann,
Virchow, and others led to the formulation of the cell theory. The cell theory
describes the properties of all cells. This theory can be summed up into three basic
components: (1) all living things are composed of one or more cells; (2) the cell is the
basic unit of life; and (3) all cells arise from pre-existing cells.
Now, that you have an understanding of the history of the cell theory, answer
the activity that follows.
What’s More
A. The Discovery of Cell
Matthias Schleiden
Anton van Leeuwenhoek
Robert Hooke
Rudolf Virchow
Theodor Schwann
Direction. Research on the ―Cell Theory‖ which tells about the discovery of cell.
Take note of the scientists and their respective works. Choose from the box which
scientist gave the following statements.
__________1. All cells come from pre-existing cells (1858).
__________2. All animals are made up of cells (1839).
__________3. All plants are made up of cells (1838).
__________4. Tiny living organisms are observed (1676).
__________5. Thousands of tiny empty chambers in cork are called cells (1665).
18
What’s New
Reflection: Answer the following questions on a separate sheet of paper.
1. What is the cell theory and what does it state?
_________________________________________________________________
2. What do we call the basic generalizations that are accepted by modern science
about cell?
_________________________________________________________________
3. Among the scientists, who advanced the cell theory with his conclusion that cells
could only come from other cells?
_________________________________________________________________
4. What discovery is Van Leeuwenhoek noted for?
_________________________________________________________________
5. What caused scientists to discover the existence of cells?
_________________________________________________________________
What I Have Learned
Direction: The figure below indicates events that lead up to the cell theory. Complete
the table by filling in the blank spaces.
Date
Scientist
Discovery
1665
a.
Observed the remains of
dead plant cells
b.
Anton van Leeuwenhoek
c.
1838
Matthias Schleiden
d.
e.
f.
Stated that all animals are
made of cells
1858
g.
h.
19
What I Can Do
Performance Task:
Research on the theory of spontaneous generation or theory of abiogenesis by
Stanley Miller and Francesco Redi and Louis Pasteur‘s experiment. Compare the two
theories on the origin of life.
Enrichment Activity:
Watch a video through YouTube link below entitled “Theories on the Origin of Life”,
https://www.youtube.com/watch?v=2QLW7I_XBqo
https://www.youtube.com/watch?v=NNijmxsKGbc
20
Lesson
2
Cell Structure and Functions
What’s In
In lesson 1, you have learned about the cell theory and the discoveries made
by scientists.
In this next topic, you will learn on the cell structure and functions that carry
out basic life processes.
What I Need to Know
All living organisms are made up of one or many cells. The cells are the
building block of life just as atoms are the basic building blocks of all matter. Each
cell contains materials that carry out basic life processes. Cell structures can only be
observed under high magnification electron microscope and are separated internally
into numerous membranous compartments called organelles (little organs). These
organelles perform a variety of functions like production of proteins, storage of
important materials, harvesting energy, repairing cell parts, digestion of substances,
and maintaining the shape and structure of the cell.
In this lesson, you will describe the structure and function of major subcellular
organelles.
21
What’s New
Direction: Write all the descriptions of cell organelles which are shown through the
illustration.
1.
Control center, stores DNA
2.
Center of the nucleus, produces ribosomes
3.
Controls passage of organic molecules, ions, water,
oxygen and wastes into and out of the cell.
4.
Provides structure to cell; gel-like fluid in which
organelles are found
5.
―Powerhouse of the cell‖, releases energy from
food
6.
Small structures for protein synthesis
22
7.
Modifies proteins and synthesizes lipids
8.
Modifies, sorts, tags, packages and
Distributes lipids and proteins
9.
Garbage disposal, digestion of macromolecules; recycling or worn out
organelles
10.
Storage and transport; digestive function
in plant cells.
11.
Site of photosynthesis, trap sunlight
to make food
12.
Protection, structural support and
maintenance of cell shape
23
What Is It
Cell Structure and Functions
Cells’ Structures
Functions
1. Cell Membrane
1. Separates cell from external
environment; controls passage of
organic molecules, ions, water, oxygen
and wastes into and out of the cell
2. Cytoplasm
2. Provides structure to cell; site of
many metabolic reactions; medium in
which organelles are found
3. Nucleolus
3. Location of DNA
4. Nucleus
4. Cell organelle that houses DNA and
directs synthesis of ribosomes and
proteins
5. Ribosomes
5. Protein synthesis
6. Mitochondria
6. ATP production or cellular respiration
7. Peroxisomes
7. Oxidizes and breaks down fatty acids
and amino acids and detoxifies poisons
8. Vesicles and Vacuoles
8. Storage and transport; digestive
function in plant cells
9. Centrosome
9. Unspecified role in cell division in
animal cells; organizing center of
microtubules in animal cells
10. Lysosomes
10. Digestion of macromolecules;
recycling or worn out organelles
11. Cell wall
11. Protection, structural support and
maintenance of cell shape
12. Chloroplast
12. Photosynthesis
13. Endoplasmic reticulum
13. Modifies proteins and synthesizes
lipids
14. Golgi apparatus
14. Modifies, sorts, tags, packages and
distributes lipids and proteins
15. Cytoskeleton
15. Maintains cell‘s shape, secure
organelles on specific positions, allows
cytoplasm and vesicles to move within
the cell, and enables unicellular
organisms to move independently
16. Flagella
16. Cellular locomotion
17. Cilia
17. Cellular locomotion, movement of
particles along extracellular surface of
plasma membrane, and filtration
24
What’s More
Direction: Below are drawing of plant and animal cells. Label the parts of the cell.
Write your answers on a separate sheet of paper according to letters and numbers.
PLANT AND ANIMAL CELL
What I Have Learned
25
Direction: Using a Venn Diagram or Tabular form show the difference between a
plant cell and animal cell.
Features
Cell Shape
Cell Wall
Cell Membrane
Nucleus
Vacuole
Plastids
Chloroplast
Endoplasmic Reticulum
Ribosomes
Mitichondria
Plant Cell
Rectangular (fixed shape)
Present and is formed of
cellulose
Present and is covered by
the cell wall
Present
A large central vacuole
taking up 90% of the cell
volume
Present
Present and make their
own food
Present
Present
Present
Animal Cell
Round (irregular shape)
Absent
Present
Present
One or more small
vacuoles
Present
Absent
Present
Present
Present
What I Can Do
Direction: Construct a 3D model of a plant/animal cell using indigenous or recyclable
materials and label the parts.
26
Lesson
3
Prokaryotic vs Eukaryotic Cells
What’s In
In lesson 2, you have learned about the cell structure and function of major
and subcellular organelles.
In this next topic, you will learn on prokaryotic and eukaryotic cells according
to their distinguishing features.
What I Need to Know
Prokaryotes vs Eukaryotes
Most living things you know such as animals and plants are multicellular
organisms. Some living things are made up of only single cell. Single-celled or
unicellular organisms include the bacteria, some protists, and some fungi. Even
though composed of single cells, these organisms carry out all the functions
necessary for life. In different organisms, cells also vary in sizes, shapes, parts, and
functions. But they all have one thing in common: they make up all living things and
they are living.
What’s New
Prokaryote
Eukaryote
Direction: In the following matrix, put a check in the box to show the organelle is
present in prokaryotic or eukaryotic cells, or both, and state in once sentence what
function of the organelle is.
27
Organelle
Cell membrane
Prokaryote
Eukaryote
Function
Cell wall
Nucleus
Mitochondria
chloroplast
Endoplasmic
reticulum (smooth)
Golgi apparatus
Lysosomes
Ribosomes
Endoplasmic
reticulum (rough)
Vacuole
What Is It
There are two kinds of organisms according to their cell structure, the
prokaryotes and eukaryotes. The difference between prokaryotic and eukaryotic
organisms is said to be the most important distinction among the groups of living
things. Prokaryotes are single-celled organisms that lack a membrane-bound
nucleus, mitochondria, and all other organelles. Its name comes from the Greek
words pro, which means ―before‖, and karyon, which means ―nut or kernel‖.
Eukaryotes are organisms with cells that contain membrane-bound nucleus and
other membrane-bound organelles. The nucleus of a eukaryotic cell contains the
genetic material (DNA), enclosed by a nuclear envelope. Other membrane-bound
organelles are mitochondria, Golgi apparatus, and chloroplast found in
photosynthetic organisms such as algae and plants. There are also unicellular
eukaryotes known as protozoa. All other eukaryotes are multicellular organisms such
as plants, animals, and fungi.
28
What’s More
For the chart below, place a check in the box if the cell has that component.
Organelle
Vacuole
Chloroplast
Ribosome
Mitochondria
DNA
Endoplasmic
Reticulum
Cell Wall
Golgi Appratus
Plant
Animal
Bacteria
What I Have Learned
Directions: On the lines below, write about what you‘ve learned by doing the
activities. Be as specific as possible and use COMPLETE SENTENCES.
1. Let me tell you some of the important things I‘ve learned about prokaryotic and
eukaryotic cells. First, I‘ll start with the difference between prokaryotic and eukaryotic
cells
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________.
2. Next, I‘ll tell you examples of prokaryotic and eukaryotic cells
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________.
3. Lastly, I now really know about and understand that prokaryotic and eukaryotic
cells
________________________________________________________________
________________________________________________________________
________________________________________________________________.
29
What I Can Do
Directions: Draw a prokaryotic (bacteria) and eukaryotic cell on a separate sheet
of paper. Label the prominent structures and if possible note the name of the
species.
30
Lesson
4
Cell Types and Cell Modification
What’s In
In lesson 3, you have learned about the difference between prokaryotic and
eukaryotic cells according to their distinguishing features.
In this next topic, you will learn on the classification of different cell types and
cell modifications that lead to adaptation to carry out specialized functions.
What I Need to Know
There are certain characteristics that all living things exhibit, the
characteristics of life. Living things are made up of cells. They metabolize, grow and
develop, respond to stimulus, adapt to their environment and reproduce. Life on
Earth exhibits organization. The atom is smallest unit of matter, followed by
molecules, which are combinations of atoms. When these molecules are grouped
together, they ultimately form a cell. The cell is the basic unit of life. In multicellular,
organisms like plants and animals, cells are grouped as tissues to perform a specific
function. Different tissues can be grouped further and form organs. The organs form
organ systems that makes the function of the body more complex and efficient.
Organs system will then form the whole organisms. All living things exhibit
organization, whether they are unicellular or multicellular organisms.
What’s New
Direction: Arrange the words according to the levels of biological organization.
organ
system
organism
31
tissue
cell
What Is It
There are hundreds of types of cells, but the four main types are epithelial
cells, connective tissue cells, muscle cells and nerve cells.
Epithelial Tissue—This type of tissue is commonly seen outside the body as
coverings or as linings of organs and cavities. Epithelial tissues are characterized by
closely-joined cells with tight junctions (i.e., a type of cell modification). Being tightly
packed, tight junctions serve as barriers for pathogens, mechanical injuries, and fluid
loss.
Cells that make up epithelial tissues can have distinct arrangements:
• cuboidal—for secretion
• simple columnar—brick-shaped cells; for secretion and active absorption
• simple squamous—plate-like cells; for exchange of material through diffusion
• stratified squamous—multilayered and regenerates quickly; for protection
• pseudo-stratified columnar—single layer of cells; may just look stacked because
of varying height; for lining of respiratory tract; usually lined with cilia (i.e., a type of
cell modification that sweeps the mucus).
Figure 1: Epithelial Tissue (Source: Reece JB, U. L. (2010). Campbell Biology 10th.
San Francisco (CA).)
32
Connective Tissue—These tissues are composed of the following:
BLOOD —made up of plasma (i.e., liquid extracellular matrix); contains water, salts,
and dissolved proteins; erythrocytes that carry oxygen (RBC), leukocytes for defense
(WBC), and platelets for blood clotting.
CONNECTIVE TISSUE PROPER (CTP)—made up of loose connective tissue that is
found in the skin and fibrous connective tissue that is made up of collagenous fibers
found in tendons and ligaments. Adipose tissues are also examples of loose
connective tissues that store fats which functions to insulate the body and store
energy.
CARTILAGE —characterized by collagenous fibers embedded in chondroitin sulfate.
Chondrocytes are the cells that secrete collagen and chondroitin sulfate. Cartilage
functions as cushion between bones.
BONE —mineralized connective tissue made by bone-forming cells called
osteoblasts which deposit collagen. The matrix of collagen is combined with calcium,
magnesium, and phosphate ions to make the bone hard. Blood vessels and nerves
are found at a central canal surrounded by concentric circles of osteons.
Figure 2: Connective Tissue (Source: Reece JB, U. L. (2010). Campbell Biology
10th. San Francisco (CA):.)
Muscle Tissue—These tissues are composed of long cells called muscle fibers that
allow the body to move voluntary or involuntary. Movement of muscles is a response
to signals coming from nerve cells. In vertebrates, these muscles can be categorized
into the following:
• skeletal—striated; voluntary movements
• cardiac—striated with intercalated disk for synchronized heart contraction;
involuntary
• smooth—not striated; involuntary
33
Figure 3: Muscle Tissue (Source: Reece JB, U. L. (2010). Campbell Biology 10th.
San Francisco (CA):.)
Nervous Tissue—These tissues are composed of nerve cells called neurons and
glial cells that function as support cells. These neurons sense stimuli and transmit
electrical signals throughout the animal body. Neurons connect to other neurons to
send signals. The dendrite is the part of the neuron that receives impulses from other
neurons while the axon is the part where the impulse is transmitted to other neurons.
Figure 4: Neurons and Glial Cells (Source: Reece JB, U. L. (2010). Campbell Biology
10th. San Francisco (CA):.)
34
What’s More
Direction: Match each general tissue category to the appropriate feature. Write the
letter of your choice before each number.
A. Connective tissue
B. Epithelium
C. Muscular tissue
D. Nervous tissue
_____1. A type of tissue that would make up the majority of the brain and spinal
cord?
_____2. Found in the epidermis and form the lining of internal organs such as the
intestines
_____3. Form the ligaments, tendons, fat and bone
_____4. A type of tissue that makes up majority of the heart
What I Have Learned
Direction: Identify which type of connective tissue (A-C), epithelial tissue (D-F), and
muscle tissue (G-I) is being described.
A. _______________transport oxygen, carbon dioxide, nutrients and waste
through the body by travelling through the vessels called arteries and veins.
B. _______________is a type of dense connective tissue that connects
muscles to bones and connects bone to bone.
C. _______________is a type of connective tissue with one of the hardest
extracellular matrixes that forms a protective structure used for muscle attachment.
D. _______________found in respiratory tract (trachea), usually lined with
cilia.
E. _______________found in air sacs/alveoli of the lungs, capillaries.
F. _______________found in digestive tract for secretion and active
absorption
G. _______________muscles of the heart; involuntary movements.
H. _______________involuntary contractions of digestive tract like
esophagus, stomach and intestines.
I. ________________striated; voluntary movements like biceps and
abdominal muscles.
What I Can Do
Direction: Give at least 4 examples of the four major tissue types. Be as specific as
possible in giving examples.
35
Lesson
Cell Cycle
5
What’s In
In lesson 4, you have learned about the classification of different cell types
and some cell modifications that lead to adaptation to carry out specialized functions.
In this next topic, you will learn on the phases of cell cycle and their control
points, stages of mitosis/meiosis, comparison and their role in the cell division cycle.
What I Need to Know
One of the distinct characteristics of living things is being able to preserve
themselves. Cells need to undergo cycles as part of their growth and to repair or
replace damaged parts. Cell cycle enables a living thing to continue its existence by
multiplying itself in controlled and systematic processes. This lesson will enhance
your understanding on cell cycle. This will provide learners with the concepts on the
different stages of cell cycle and the two types of cell division: mitosis and meiosis
and explain their significance on an organism.
What’s New
Direction: Label the diagram below with the following labels:
Anaphase
Cell division (M Phase)
Cytokinesis
G1 –cell grows
G2- prepares for mitosis
S-DNA replication
Metaphase
Prophase
Telophase
Interphase
Mitosis
36
The Cell Cycle Coloring Worksheet
Then on the diagram, lightly color the G1 phase light GREEN, the S
phase dark BLUE, the G2 phase light BLUE, and the stages of mitosis VIOLET.
Color the arrows indicating all of the interphases in BLUE. Color the part of the arrow
indicating mitosis PURPLE and the part of the arrow indicating cytokinesis light
VIOLET.
What Is It
Cell Division—involves the distribution of identical genetic material or DNA to two
daughter cells. What is most remarkable is the fidelity with which the DNA is passed
along, without dilution or error, from one generation to the next. Cell Division
functions in reproduction, growth, and repair.
Core Concepts:
• All organisms consist of cells and arise from preexisting cells.
• Mitosis is the process by which new cells are generated.
• Meiosis is the process by which gametes are generated for reproduction.
• The Cell Cycle represents all phases in the life of a cell.
• DNA replication (S phase) must precede mitosis so that all daughter cells receive
the same complement of chromosomes as the parent cell.
• The gap phases separate mitosis from S phase. This is the time when molecular
signals mediate the switch in cellular activity.
• Mitosis involves the separation of copied chromosomes into separate cells.
37
• Unregulated cell division can lead to cancer.
• Cell cycle checkpoints normally ensure that DNA replication and mitosis occur only
when conditions are favorable and the process is working correctly.
• Mutations in genes that encode cell cycle proteins can lead to unregulated growth,
resulting in tumor formation and ultimately invasion of cancerous cells to other
organs.
The Cell Cycle control system is driven by a built-in clock that can be adjusted by
external stimuli (i.e., chemical messages).
Checkpoint—a critical control point in the Cell Cycle where ‗stop‘ and ‗go-ahead‘
signals can regulate the cell cycle.
• Animal cells have built-in ‗stop‘ signals that halt the cell cycles and checkpoints until
overridden by ‗go-ahead‘ signals. • Three major checkpoints are found in the G1, G2,
and M phases of the Cell Cycle.
The G1 Checkpoint—the Restriction Point
• The G1 checkpoint ensures that the cell is large enough to divide and that enough
nutrients are available to support the resulting daughter cells.
• If a cell receives a ‗go-ahead‘ signal at the G1 checkpoint, it will usually continue
with the Cell Cycle. • If the cell does not receive the ‗go-ahead‘ signal, it will exit the
Cell Cycle and switch to a non-dividing state called G0.
• Most cells in the human body are in the G0 phase.
The G2 Checkpoint—ensures that DNA replication in S phase has been
successfully completed.
The Metaphase Checkpoint—ensures that all of the chromosomes are attached to
the mitotic spindle by a kinetochore.
Kinase—a protein which activates or deactivates another protein by phosphorylating
them. Kinases give the ‗go-ahead‘ signals at the G1 and G2 checkpoints. The
kinases that drive these checkpoints must themselves be activated.
• The activating molecule is a cyclin, a protein that derives its name from its cyclically
fluctuating concentration in the cell. Because of this requirement, these kinases are
called cyclin-dependent kinases or CDKs.
• Cyclins accumulate during the G1, S, and G2 phases of the Cell Cycle.
• By the G2 checkpoint, enough cyclin is available to form MPF complexes
(aggregations of CDK and cyclin) which initiate mitosis.
• MPF functions by phosphorylating key proteins in the mitotic sequence.
• Later in mitosis, MPF switches itself off by initiating a process which leads to the
destruction of cyclin. • CDK, the non-cyclin part of MPF, persists in the cell as an
inactive form until it associates with new cyclin molecules synthesized during the
interphase of the next round of the Cell Cycle.
Discuss the stages of mitosis and meiosis.
Mitosis (apparent division)—is nuclear division; the process by which the nucleus
divides to produce two new nuclei. Mitosis results in two daughter cells that are
genetically identical to each other and to the parental cell from which they came.
Cytokinesis—is the division of the cytoplasm. Both mitosis and cytokinesis last for
around one to two hours.
Prophase—is the preparatory stage, during prophase, centrioles move toward
opposite sides of the nucleus.
• The initially indistinct chromosomes begin to condense into visible threads.
38
• Chromosomes first become visible during early prophase as long, thin, and
intertwined filaments but by late prophase, chromosomes are more compacted and
can be clearly discerned as much shorter and rod-like structures.
• As the chromosomes become more distinct, the nucleoli also become more distinct.
By the end of prophase, the nucleoli become less distinct, often disappearing
altogether.
Metaphase—is when chromosomes become arranged so that their centromeres
become aligned in one place, halfway between the two spindle poles. The long axes
of the chromosomes are 90 degrees to the spindle axis. The plane of alignment is
called the metaphase plate.
Anaphase—is initiated by the separation of sister chromatids at their junction point
at the centromere. The daughter chromosomes then move toward the poles.
Telophase—is when daughter chromosomes complete their migration to the poles.
The two sets of progeny chromosomes are assembled into two-groups at opposite
ends of the cell. The chromosomes uncoil and assume their extended form during
interphase. A nuclear membrane then forms around each chromosome group and
the spindle microtubules disappear. Soon, the nucleolus reforms.
Meiosis—reduces the amount of genetic information. While mitosis in diploid cells
produces daughter cells with a full diploid complement, meiosis produces haploid
gametes or spores with only one set of chromosomes. During sexual reproduction,
gametes combine in fertilization to reconstitute the diploid complement found in
parental cells. The process involves two successive divisions of a diploid nucleus.
First Meiotic Division The first meiotic division results in reducing the number of
chromosomes (reduction division). In most cases, the division is accompanied by
cytokinesis.
Prophase I—has been subdivided into five substages: leptonema, zygonema,
pachynema, diplonema, and diakinesis.
• Leptonema—Replicated chromosomes have coiled and are already visible. The
number of chromosomes present is the same as the number in the diploid cell.
• Zygonema—Homologue chromosomes begin to pair and twist around each other
in a highly specific manner. The pairing is called synapsis. And because the pair
consists of four chromatids it is referred to as bivalent tetrad.
• Pachynema—Chromosomes become much shorter and thicker. A form of physical
exchange between homologues takes place at specific regions. The process of
physical exchange of a chromosome region is called crossing-over. Through the
mechanism of crossing-over, the parts of the homologous chromosomes are
recombined (genetic recombination).
• Diplonema—The two pairs of sister chromatids begin to separate from each other.
It is at this point where crossing-over is shown to have taken place. The area of
contact between two non-sister chromatids, called chiasma, become evident.
• Diakinesis—The four chromatids of each tetrad are even more condensed and the
chiasma often terminalize or move down the chromatids to the ends. This delays the
separation of homologous chromosomes.
In addition, the nucleoli disappear, and the nuclear membrane begins to break down.
Metaphase I—The spindle apparatus is completely formed and the microtubules are
attached to the centromere regions of the homologues. The synapsed tetrads are
39
found aligned at the metaphase plate (the equatorial plane of the cell) instead of only
replicated chromosomes.
Anaphase I—Chromosomes in each tetrad separate and migrate toward the
opposite poles. The sister chromatids (dyads) remain attached at their respective
centromere regions.
Telophase I—The dyads complete their migration to the poles. New nuclear
membranes may form. In most species, cytokinesis follows, producing two daughter
cells. Each has a nucleus containing only one set of chromosomes (haploid level) in
a replicated form.
Second Meiotic Division The events in the second meiotic division are quite similar to
mitotic division. The difference lies, however, in the number of chromosomes that
each daughter cell receives. While the original chromosome number is maintained in
mitosis, the number is reduced to half in meiosis.
Prophase II—The dyads contract.
Metaphase II—The centromeres are directed to the equatorial plate and then divide.
Anaphase II—The sister chromatids (monads) move away from each other and
migrate to the opposite poles of the spindle fiber.
Telophase II—The monads are at the poles, forming two groups of chromosomes. A
nuclear membrane forms around each set of chromosomes and cytokinesis follows.
The chromosomes uncoil and extend.
Cytokinesis—The telophase stage of mitosis is accompanied by cytokinesis. The
two nuclei are compartmentalized into separate daughter cells and complete the
mitotic cell division process. In animal cells, cytokinesis occurs by the formation of a
constriction in the middle of the cell until two daughter cells are formed. The
constriction is often called cleavage, or cell furrow. However, in most plant cells this
constriction is not evident. Instead, a new cell membrane and cell wall are
assembled between the two nuclei to form a cell plate. Each side of the cell plate is
coated with a cell wall that eventually forms the two progeny cells.
Table 1: Comparison of Mitosis and Meiosis
(Source:http://courses.washington.edu/bot113/spring/WebReadings/PdfReadings/TA
BLE_COMPARING_MITOSIS_AND.pdf)
40
Disorders and Diseases
• incorrect DNA copy (e.g., cancer)
• chromosomes are attached to string-like spindles and begin to move to the middle
of the cell (e.g., Down Syndrome, Alzheimer‘s, and Leukemia)
Other chromosome abnormalities:
• arise from errors in meiosis, usually meiosis I;
• occur more often during egg formation (90% of the time) than during sperm
formation;
• become more frequent as a woman ages.
• Aneuploidy—is the gain or loss of whole chromosomes. It is the most common
chromosome abnormality. It is caused by non-disjunction, the failure of
chromosomes to correctly separate:
• homologues during meiosis I or
• sister chromatids during meiosis II
What’s More
Direction: Complete the chart by noting what occurs in each phase of the cell cycle.
Gap O (GO)
Interphase
Gap 1 (G1)
S Phase
Gap 2 (G2)
Prophase
Mitosis or M
Phase
Metaphase
Anaphase
Telophase
Cytokinesis
C
41
What I Have Learned
Direction: The diagram below shows cells in various phases of the cell cycle. Note
the cells are not arranged in the order in which the cell cycle occurs. Use the
diagram to answer questions 1-6. Write you answer in CAPITAL letters.
1. ________Interphase (G2)
4. _________Metaphase
2. ________Prophase
5. _________Anaphase
3. ________Prometaphase
6. _________Telophase & Cytokinesis
What I Can Do
Direction: Gene mutations in a cell can result in uncontrolled cell division, called
cancer. Exposure of cells to certain chemicals and radiation increases mutations
and thus increases the chance of cancer. Research on the causes of cancers and
disorders/diseases that result from the malfunction of the cell during the cell cycle
and answer the following questions.
1. Define cancer
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________.
2. What are the causes of cancer?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________.
42
Summary
The importance of cell cycle is very evident that the growth and
sustainability of multicellular organisms depend on this process. Cells that are
damaged and lost will be replenished when cells divide. Errors in mitosis lead to an
incorrect copy of the DNA which may produce deadly functional consequences
depending on the error. The positive correlation with the malfunction of these
processes to the onset of major diseases such as cancer, stroke, atherosclerosis,
inflammation, and some neurodegenerative disorders in increasingly proven in
various studies.
43
Assessment: (Post-Test)
Direction: Select the letter of your choice. Write it in CAPITAL letters. Your answers should be
written on a separate sheet of paper.
__1. Which level of organization is the basic unit of life?
A. Cell
B. Tissue
C. Organ
D. System
__2. Which of the following is NOT a postulate of a unified cell theory?
A. All living things are composed of cells
B. Cells are the basic unit of life
C. All cells undergo complete development
D. All new cells arise from existing cells
__3. Who coined the term cell for the box like structure he observed when viewing cork tissue?
A. Matthias Schleiden
B. Theodor Schwann
C. Rudolf Virchow
D. Robert Hooke
__4. In many cells, the structure that controls the cell activities is the _____________.
A. Cell Membrane
B. Organelle
C. Nucleolus
D. Nucleus
__5. Which part of the cell serves as venue for cellular respiration and is known as the powerhouse of
the cell?
A. Nucleolus
B. Chromosome
C. Mitochondrion
D. Nucleus
__6. Which type of tissue would be found in the epidermis and form the lining of internal organs such
as the intestines?
A. Nervous tissue
B. Muscular tissue
C. Connective tissue
D. Epithelial tissue
__7. The process by which the nucleus divides to produce two new nuclei that results in two
daughter cells that are genetically identical to each other and to the parental cell from which
they came.
A. Meiosis
B. Interphase
C. Mitosis
D. Cytokinesis
__8. A type of passive transport which relies on carrier proteins in order for the substances to move
down their concentration gradient.
A. Active transport
B. Facilitated diffusion
C. Osmosis
D. Sodium-potassium pump
44
__9. Which of the following is an example of passive transport which occurs when particles move
from an area of higher concentration to an area of lower concentration?
A. Phagocytosis
B. Pinocytosis
C. Diffusion
D. Osmosis
__10. This process utilizes additional metabolic energy against the concentration gradient to move
molecules across the membrane from a region of lower concentration to a region of higher
concentration.
A. Active Transport
B. Passive Transport
C. Osmosis
D. Exocytosis
Key to Answers
A. Pre-test and Post test
1. A
2. C
3. D
4. D
5. C
6. D
7. C
8. B
9. C
10. A
LESSON 1 CELL THEORY
What’s New
1. ALL LIVING THINGS ARE COMPOSED OF ONE OR MORE CELLS.
2. THE CELL IS THE BASIC UNIT OF LIFE.
3. ALL CELLS ARISE FROM PRE-EXISTING CELLS.
What’s More
A. The Discovery of Cell
1. RUDOLF VIRCHOW
2. THEODOR SCHWANN
3. MATTHIAS SCHLEIDEN
4. ANTON VAN LEEUWENHOEK
5. ROBERT HOOKE
45
What’s New
1. What is the cell theory and what does it state?
Cell theory states that living things are composed of one or more cells, that the cell is the basic unit
of life, and that cells arise from existing cells.
2. What do we call the basic generalizations that are accepted by modern science about cell?
Cell Theory
3. Among the scientists, who advanced the cell theory with his conclusion that cells could only come
from other cells?
Rudolf Virchow
4. What discovery is Van Leeuwenhoek noted for?
Anton van Leeuwenhoek used single-lens microscopes which he made to make the first
observations of bacteria and protozoa.
5. What caused scientists to discover the existence of cells?
The development of the microscope.
What I have Learned
a. Robert Hooke
b. 1676
c. Tiny living organisms which he named animalcules under his microscope.
d. All plant parts are made of cells
e. 1839
f. Theodor Schwann
g. Rudolf Virchow
h. All cells come from pre-existing cells
LESSON 2 CELL STRUCTURE AND FUNCTIONS
What’s New
1. Nucleus
7. Endoplasmic reticulum
2. Nucleolus
8. Golgi apparatus
3. Plasma membrane
9. Lysosomes
4. Cytoplasm
10. Vesicles and vacuoles
5. Mitochondria
11. Chloroplast
6. Ribosome
12. Cell wall
46
What’s More
Plant Cell
Animal Cell
A – Vacuole
1. Mitochondria
B - Cell Wall
2. Lysosome
C - Endoplasmic Reticulum
3. Vacuole
D - Nucleus
4. Cytoplasm
E - Mitochondria
5. Nucleolus
F - Chloroplast
6. Nucleus
G - Golgi apparatus
7. Chromatin
8. Microfilaments
9. Rough Endoplasmic Reticulum
10. Golgi Apparatus
11. Intermediate filaments
12. Golgi vesicle
13. Ribosome
14. Smooth Endoplasmic Reticulum
15. Plasma Membrane
What I Have Learned
Venn Diagram
Plant Cell
Cell Shape
(rectangular)
Cell Wall
Large Vacuoles
Chloroplast
Animal Cell
Cell Membrane
Nucleus
Plastids
Endoplasmic
reticulum
Ribosomes
Mitochondria
47
Cell Shape (circular)
Small Vacuoles
LESSON 3 PROKARYOTIC VS EUKARYOTIC CELLS
What’s New
Organelle
Cell membrane
Cell wall
Nucleus
Mitochondria
Prokaryote
Eukaryote
√
√ complex
√
√ plants
√
√
√
√
chloroplast
Endoplasmic
reticulum (smooth)
Golgi apparatus
Lysosomes
Ribosomes
Endoplasmic
reticulum (rough)
Vacuole
√smaller
Function
√
√
√ larger
√
√
√
Plant
Animal
Bacteria
√
√
√
√
√
√
√
√
√
√
√
√
√
What’s More
Organelle
Vacuole
Chloroplast
Ribosome
Mitochondria
DNA
Endoplasmic
Reticulum
Cell Wall
Golgi Apparatus
√
√
√
√
√
LESSON 4 CELL TYPES AND CELL MODIFICATION
What’s new
cell
tissue
organ
system
What’s More
1. D
2. B
3. A
4. C
48
organism
What I Have Learned
A. BLOOD
B. CARTILAGE
C. BONE
D. PSEUDO-STRATIFIED COLUMNAR
E. SIMPLE SQUAMOS
F. SIMPLE COLUMNAR
G. CARDIAC
H. SMOOTH
I. SKELETAL
LESSON 5 CELL CYCLE
What’s New
The Cell Cycle Coloring Worksheet
49
What’s More
Interphase
Gap O (GO)
Gap 1 (G1)
S Phase
Gap 2 (G2)
Mitosis or M
Phase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
C
What I Have Learned
1. D
2. A
3. F
4. C
5. E
6. B
What I can do
1. Cancer is a term for diseases in which abnormal cells divide without control and can invade nearby
tissues.
50
2. Cancer is caused by accumulated damage to genes. Such changes may be due to chance or to
exposure to a cancer causing substances.
Risk Factors:
1. Biological or internal factors such as age, gender, inherited genetic defects and skin types
2. Environmental exposure
3. Occupational risk factors including carcinogens such as chemicals, radioactive materials and
asbestos
4. Lifestyle-related factors like tobacco, alcohol, UV radiation in sunlight, food-related such as
nitrites and Poly aromatic hydrocarbons.
51
References
Manuals/Modules/Lesson Exemplar
Department of Education. The Commission on Higher Education in collaboration with
Philippine Normal University. Teaching Guide for Senior High School. General
Biology 1. 2016
Department of Education Central Office. Most Essential Learning Competencies
(MELCs). 2020.
Websites
http://mrsobermeyer.weebly.com/uploads/3/8/3/0/38303365/unit_2_cells__structure___function__.pdf
https://ghr.nlm.nih.gov/primer/basics/cell
https://www.henhudschools.org/cms/lib/NY01813707/Centricity/Domain/1390/HW%2
012%20-%20Cell%20Theory%20I.pdf
https://www.easyteacherworksheets.com/science/answerno-cells.html
http://images.pcmac.org/SiSFiles/Schools/AL/SaralandCitySchools/SaralandHigh/Up
loads/Forms/Tissues_Review_Packet.pdf
https://www.cellsalive.com/cell_cycle_js.htm
https://cpb-use1.wpmucdn.com/cobblearning.net/dist/3/4046/files/2017/07/cells_exploration_activitiesvorv1v.pdf
https://www.lincnet.org/cms/lib05/MA01001239/Centricity/Domain/108/cells_exploration_acti
vities.pdf
https://www.henhudschools.org/cms/lib/NY01813707/Centricity/Domain/1390/HW%2012%2
0-%20Cell%20Theory%20I.pdf
https://www.cusd80.com/cms/lib/AZ01001175/Centricity/Domain/4939/Chapter%203%20CK12%20Biology%20Chapter%203%20Worksheets.pdf
http://images.pcmac.org/SiSFiles/Schools/AL/SaralandCitySchools/SaralandHigh/Uploads/F
orms/Tissues_Review_Packet.pdf
https://cpb-us-e1.wpmucdn.com/cobblearning.net/dist/3/4046/files/2017/07/10.2A-CellCycle-Coloring-KEY-28ad9ub.pdf
https://www.cusd80.com/cms/lib/AZ01001175/Centricity/Domain/4939/Chapter%205%20%2
0CK-12%20Biology%20Chapter%205%20Worksheets.pdf
52
https://www.studocu.com/en-us/document/rochester-institute-of-technology/explorations-incellular-biology-and-evolution/lecture-notes/the-cell-cycle-worksheet-withanswers/3510184/view
https://www.urmc.rochester.edu/life-sciences-learning-center/resourceslessons/lessons.aspx
53
Lesson
Transport Mechanisms
6
What I Need to Know

Learning Competencies:
1. Describe the structural components of the cell membrane
(STEM_BIO11/12-Ig-h-11)
2. Relate the structure and composition of the cell membrane to its function
(STEM_BIO11/12-Ig-h-12)
3. Explain transport mechanisms in cells (diffusion, osmosis, facilitated
transport, active transport) (STEM_BIO11/12-Ig-h-13)
4. Differentiate exocytosis and endocytosis (STEM_BIO11/12-Ig-h-14)

Performance Standards:
The learners should be able to construct a cell membrane model from
indigenous or recyclable materials.

Introduction:
With the pandemic today in the Philippines, you can just imagine our
Cagayan de Oro‘s front liners and law enforcers at the check points of a
city or security guards at the mall entrances (Fig. 7.a) as plasma
membranes (cell membranes) which have a lot of things to do such as
permitting who‘ll enter the establishment (represents the cell) or not and
even exiting is checked as well; Carrying goods in a truck or individuals on
a motorcycle towards a particular cordoned area which depicts different
means or ways on how materials are transported in and out of the cell thus the transport mechanisms.
In cellular biology, membrane transport refers to the collection of
mechanisms that regulate the passage of solutes such as ions and small
molecules through biological membranes, which are lipid bilayers that
contain proteins embedded in them.
54
Plasma membrane (Cell Membrane) plays a vital role in the transport
mechanisms and separates the living cell from its surroundings. To perform
these roles, it needs lipids, which make a semi-permeable barrier between
the cell and its environment. It also needs proteins, which are involved in
cross-membrane transport and cell communication, and carbohydrates
(sugars and sugar chains), which decorate both the proteins and lipids and
help cells recognize each other.
Fig. 7.a Even in a mall or at the checkpoints, the people and objects move from one
location to another; they cross or are contained within certain boundaries. Analogously, a
cell membrane‘s functions involve movement within the cell and across the boundaries in
the process of intracellular and intercellular activities. Just like the law enforcers or security
guards, they allow some substances to pass through, but not others.
.
6.1 Structural Components of the Cell Membrane
What I Know
Write the letter of the best answer in the blank.
_____1. Which plasma membrane component can be either found on its surface or
embedded in the membrane structure?
a. protein
b. cholesterol
c. carbohydrate
d. phospholipid
_____2. What is the primary function of carbohydrates attached to the exterior of cell
membranes?
a. identification of the cell
b. flexibility of the membrane
c. strengthening the membrane
d. channels through membrane
55
_____3. Which characteristic of a phospholipid contributes to the fluidity of the
membrane?
a. its head
b. cholesterol
c. a saturated fatty acid tail
d. double bonds in the fatty acid tail
_____4. Which interacts to hydrophilic and hydrophobic environments?
a. protein
b. cholesterol
c. phospholipid
d. carbohydrate
_____5. Carbohydrates is found outside the surface of the cell and bounded with?
a. lipid or protein
b. phospholipid
c. glycoprotein
d. glycolipid
Provide the description of each structural components of the cell membrane
regarding its location and features inside the empty blanks.
COMPONENT
LOCATION
FEATURE/FUNCTION
Phospholipids
Main fabric of the membrane
 the most abundant lipid
in the plasma membrane
6.___________________
___________________
Cholesterol
7.___________________
___________________
Dampen effects of
temperature
Integral Proteins
Embedded in the phospholipid
bilayer; may or may not extend
through both layers
8.___________________
___________________
Peripheral
Proteins
On the inner or outer surface of
the phospholipid bilayer, but not
embedded in its hydrophobic
core
9.___________________
___________________
Carbohydrate
Chains
10.___________________
___________________
 Cell recognition
 Effective interaction with
the acqueous
environment
56
What’s In
•
REVIEW: The Structural Components of the Cell Membrane
The modern understanding of the cellular or plasma membrane is referred to
as the fluid mosaic model or fluid mosaics of lipids and proteins. It is composed of a
bilayer of phospholipids, with their hydrophobic, fatty acid tails in contact with each
other (Fig. 7.d). The landscape of the membrane is studded with proteins, some of
which span the membrane. Some of these proteins serve to transport materials into
or out of the cell. Carbohydrates are attached to some of the proteins and lipids on
the outward-facing surface of the membrane (Fig. 7.b.), forming complexes which
function is to identify the cell to other cells. Cell membranes enclose and define the
borders of cells, but rather than being a static bag, they are dynamic and constantly
in flux.
Fig. 7.b. Structural Component of Cellular Membrane
Fig. 7.c. In 1935, Davson-Danielli, the sandwich model of membrane structure stated that the
membrane was made up of a phospholipid bilayer sandwiched between two protein layers.
57
Fig. 7.d. In 1972, S. J. Singer and G. Nicolson proposed that the membrane is a mosaic of proteins
dispersed within the bilayer, with only the hydrophilic regions exposed to water.
The Fluidity of the membrane is due to temperature, the configuration of the
unsaturated fatty acid tails (some kinked or form a sharp twist by double bonds), the
presence of cholesterol embedded in the membrane, and the mosaic nature of the
proteins and protein-carbohydrate combinations, which are not firmly fixed in place.
Key Takes of the Fluid Nature of the CM:
• Phospholipids in the plasma membrane can move within the bilayer (Fig. 7.e)
• Most of the lipids, and some proteins, drift laterally
• Rarely does a molecule flip-flop transversely across the membrane
Fig. 7.e.
Lateral movement occurs 107
times per second.
Flip-flopping across the membrane is
rare (~ once per month).
58
• As temperatures cool, membranes switch from a fluid state to a solid state.
• The temperature at which a membrane solidifies depends on the types of lipids.
• Membranes rich in unsaturated fatty acids are more fluid than those rich in
saturated fatty acids. (Fig. 7.f.)
• Membranes must be fluid to work properly; they are usually about as fluid as salad
Oil.
Fig. 7.f. The type of hydrocarbon tails in phospholipids – Affects the fluidity of the cell membrane
Fluid
Viscous
Saturated hydrocarbon tails
Unsaturated hydrocarbon tails
(a) Unsaturated versus
saturated hydrocarbon tails
(b) Cholesterol within the
animal cell membrane
Cholesterol
• The steroid cholesterol has different effects on membrane fluidity at different
temperatures.
• At warm temperatures (such as 37°C), cholesterol restrains movement of
Phospholipids.
• At cool temperatures, it maintains fluidity by preventing tight packing.
59
Structural Component of the Cell Membrane (Plasma Membrane)
COMPONENT
LOCATION
FEATURE/FUNCTION
Phospholipids
Main fabric of the membrane
 the most abundant lipid
in the plasma membrane
 are amphipathic
molecules
Cholesterol
Tucked between the hydrophobic
tails of the membrane
phospholipids
Dampen effects of
temperature
Integral Proteins
Embedded in the phospholipid
bilayer; may or may not extend
through both layers
Transport of substance
through membrane
Peripheral
Proteins
Carbohydrate
Chains
On the inner or outer surface of
the phospholipid bilayer, but not
embedded in its hydrophobic
core
Attached to proteins or lipids on
the extracellular side of the
membrane (forming
glycoproteins and glycolipids
Cell recognition
 Cell recognition
 Effective interaction with
the acqueous
environment
Terminology:
Amphiphilic or Amphipathic
 molecule possessing a polar or charged area and a nonpolar or uncharged area
capable of interacting with both hydrophilic and hydrophobic environments
Fluid mosaic model
 describes the structure of the plasma membrane as a mosaic of components
including phospholipids, cholesterol, proteins, glycoproteins, and glycolipids
(sugar chains attached to proteins or lipids, respectively), resulting in a fluid
character (fluidity)
Glycolipid
 combination of carbohydrates and lipids
Glycoprotein
 combination of carbohydrates and proteins
Hydrophilic
 molecule with the ability to bond with water; ―water-loving‖
Hydrophobic
 molecule that does not have the ability to bond with water; ―water-hating‖
60
Integral protein
 protein integrated into the membrane structure that interacts extensively with the
hydrocarbon chains of membrane lipids and often spans the membrane; these
proteins can be removed only by the disruption of the membrane by detergents
Peripheral protein
 protein found at the surface of a plasma membrane either on its exterior or
interior side; these proteins can be removed (washed off of the membrane) by a
high-salt wash
What’s New
•
Visual and Listening Activity:
1. A video link is provided ; ―Fluid mosaic model of cell membranes‖ | Biology | by
Khan Academy (2015), https://youtu.be/cP8iQu57dQo
2. Watch and Listen carefully to the video and be able to recognize and relate to
each attributes of the structural components of the membrane.
3. Reflect on your life experiences and relate them to the lesson in the video so that
you will be able to write a story analogous to the structural components of the cell
membrane.
4. Write the story neatly on a long bond paper.
What Is It
•
Q & A Activity:
1. What happens to the plasma membrane if the weather gets cold?
2. Are there structural components involved in the membrane that are affected from
the rise and fall of the temperature? What are those structures?
3. What does Fig. 7.f imply regarding the fatty acid or hydrocarbon tail‘s shape when
compared and contrasted in relation with transport mechanism? Explain your
answer.
(Write your answers on a ½ crosswise intermediate paper.)
61
What’s More
•
Drafting from Visual and Listening Activity:
1. A video link is provided ; ―Construction of the Cell Membrane‖ by Becky PolkPohlman Barbara Liang; https://www.wisc-online.com/learn/natural-science/lifescience/ap1101/construction-of-the-cell-membrane
2. Watch and Listen carefully for you to be able to make a rough draft sketch of the
individual structural components of the membrane through the video clip.
3. Prepare your final draft sketch to me with labels of the indigenous /recyclable
materials you will utilize for each of the structural components for the next activity.
5. Write your sketch neatly on a long bond paper.
What I Have Learned
•
Learning Process Activity:
Provide the best answer in the blank.
1. The modern understanding of the cellular or plasma membrane is referred to as
the ______________ or ______________.
2. It is composed of a bilayer of ______________.
3. ______________ are attached to some of the proteins and lipids on the outwardfacing surface of the membrane.
4. ______________is a function of Carbohydrates.
5. The fluid nature of the membrane is due to ______________.
6. Cell membranes ______________ and ______________ the borders of cells.
7. ______________ refers to the collection of mechanisms that regulate the
passage of solutes.
8. ______________ integrated into the membrane structure that interacts
extensively with the hydrocarbon chains of membrane lipids.
62
What I Can Do
•
Performance Activity:
Construct a cell membrane model from indigenous or recyclable materials.
1. Prepare your final draft sketch with labels of the indigenous /recyclable materials
that you will utilize for each of the structural components for this activity.
2. Prepare your indigenous /recyclable materials and tools kits to start constructing
the cell membrane model.
3. Set your output on a 2x2 sturdy and used illustration board or any platform.
4. Keep your output in a safe place and submit it on the exact date of submission to
be announced by your teacher.
6.2 The Relationship of the Structure and Composition
of the Cell Membrane to its Function
What I Know
Write the letter of the best answer in the blank.
_____1. The primary function of the plasma membrane is ….
a. to protect the cell from its surroundings.
b. to provide shape and integrity to the cell.
c. to maintains the cell potential.
d. to be a fluid mosaic model.
_____2. What is the primary function of carbohydrates attached to the exterior of cell
membranes?
a. identification of the cell
b. flexibility of the membrane
c. strengthening the membrane
d. channels through membrane
63
_____3. Cellular Signaling relation to the Plasma Membrane is….
a. to protect intracellular components from the extracellular environment.
b. to enclose and define the borders of the cell
c. to transmit signals via complex proteins
d. to transport materials into or out of the cell
_____4. Cellular Transport Mechanism‘s relation to the Plasma Membrane is…
a. to protect intracellular components from the extracellular environment.
b. to transport materials into or out of the cell
c. to enclose and define the borders of the cell
d. to transmit signals via complex proteins
_____5. Vital for cellular signalling processes that influence tissue and organ
formation
a. membrane markers
b. membrane receptors
c. glycoprotein
d. glycolipid
Provide the the Funtions related to the Structures and Compositions of the Cell
Membrane inside the empty blanks.
Structure or Component
Function
6.________________________________________
Phospholipid Bilayer
________________________________________
.7.________________________________________
Membrane Markers
________________________________________
8.________________________________________
Cytoskeleton
________________________________________
9.________________________________________
Transmembrane Protein
________________________________________
10.________________________________________
Membrane Receptors
________________________________________
64
What’s In
•
REVIEW: The Structure and Composition of the Cell Membrane relation
to its Function
The plasma membrane protects the cell from its external environment,
mediates cellular transport, and transmits cellular signals.




The principal components of the plasma membrane are lipids (phospholipids
and cholesterol), proteins, and carbohydrates.
The plasma membrane protects intracellular components from the extracellular
environment.
The plasma membrane mediates cellular processes by regulating the materials
that enter and exit the cell.
The plasma membrane carries markers that allow cells to recognize one
another and can transmit signals to other cells via receptors.
The plasma membrane (also known as the cell membrane or cytoplasmic
membrane) is a biological membrane that divides the interior of a cell from its outside
environment. (Figure 7.g)
The primary function of the plasma membrane is to protect the cell from its
surroundings. Composed of a phospholipid bilayer with embedded proteins, the
plasma membrane is selectively permeable to ions and organic molecules and
regulates the movement of substances in and out of cells. Plasma membranes must
be very flexible in order to allow certain cells, such as red blood cells and white blood
cells, to change shape as they pass through narrow capillaries.
The plasma membrane also plays a role in anchoring the cytoskeleton to
provide shape and integrity to the cell, and in attaching to the extracellular matrix and
other cells to help group cells together to form tissues. The membrane also
maintains the cell potential.
In short, if the cell is represented today as a COVID FREE-CAGAYAN DE
ORO CITY, then the plasma membrane is the checkpoints with the frontliners and
law enforcers that provides protective and territorial structure for the city inside,
depicting separation or barrier, regulates which people leave and enter the city, and
conveys messages to and from neighbouring cities.
Just as an unguarded check point in the surrounding barrier can be a disaster
for the city in today‘s crisis, like a rupture in the plasma membrane causes the cell to
lyse and die.
65
Cellular Signaling/ Recognition’s relation to the Plasma Membrane
Among the most sophisticated functions of the plasma membrane is its ability
to transmit signals via complex proteins. These proteins can be receptors, which
work as receivers of extracellular inputs and as activators of intracellular processes,
or markers, which allow cells to recognize each other.
Membrane receptors provide extracellular attachment sites for effectors like
hormones and growth factors, which then trigger intracellular responses. Some
viruses, such as Human Immunodeficiency Virus (HIV), can hijack these receptors to
gain entry into the cells, causing infections.
Membrane markers allow cells to recognize one another, which is vital for
cellular signaling processes that influence tissue and organ formation during early
development. This marking function also plays a later role in the ―self‖-versus-―nonself‖ distinction of the immune response. Marker proteins on human red blood cells,
for example, determine blood type (A, B, AB, or O).
Terminology:
Receptor
 A protein on a cell wall that binds with specific molecules so that they can be
absorbed into the cell.
Cellular Transport Mechanisms’ relation to the Plasma Membrane
The movement of a substance across the selectively permeable plasma
membrane can be either ―passive‖—i.e., occurring without the input of cellular
energy —or ―active‖—i.e., its transport requires the cell to expend energy.
The cell employs a number of transport mechanisms that involve biological
membranes:
1. Passive osmosis and diffusion: transports gases (such as O 2 and CO2) and
other small molecules and ions
2. Transmembrane protein channels and transporters: transports small organic
molecules such as sugars or amino acids
3. Endocytosis: transports large molecules (or even whole cells) by engulfing
them
4. Exocytosis: removes or secretes substances such as hormones or enzymes.
66
Fig. 7.g. Detailed Image of Cell Membrane Structure in a Cell
67
What’s New
•
Activity:
Identify the structural components of the cell membrane and provide the boxes with
the best answers
1.
2.
8.
3.
4.
6.
7.
5.
What Is It
•
Q & A Activity:
1. Can you remember all the structural components of a cell membrane and be able
to list them down? If so, just list down at least 10 along with its functions.
2. Are there structures or components related in the membrane‘s transport
mechanisms? What are those? Write at least 5 and indicate why they are related.
(Write your answers on a ½ crosswise intermediate paper.)
68
What’s More
•
Visual and Listening Activity:
1. A video link is provided ; ―Inside the Cell Membrane‖ by Amoeba Sisters (Feb 28,
2018), https://www.youtube.com/watch?v=qBCVVszQQNs
2. Watch and Listen carefully for you to be able to associate the components and
structures of the cell membrane to your household.
3. Make an analogous reflection paper of your household to the structures and
components of the cell membrane. Prioritize on the function aspect.
4. Write it on a long bond paper.
What I Have Learned
•
Learning Process Activity:
1. Provide insights on how the structures and components of the cell membrane is
related to its function with regards to the Celular Signalling/Recognition.
2. Give your Take Aways on Cellular Transport Mechanisms‘ relation to the Plasma
Membrane emphasizing more on its function.
3. Write it on a long bond paper.
What I Can Do
•
Performance Activity:
1. Craft a task plan on a long bond paper regarding the tasks on what functions you
can contribute to your household during this time of crisis. Include also listing down
the house members functions contributing in your home.
2. Document this task in a week. Photos included in a separate paper or soft copy.
69
Template (example)
SUN
01/21/20
MON
_/_/20
TUE
_/_/20
WED
_/_/20
THU
_/_/20
FRI
_/_/20
SAT
_/_/20
PARENT/GUARDIAN
Printed name,
Signature and Date
Portgas D. Ace
AM
PM
-sanitized
the
bathroom
-washed
the dishes
-swept
outside
the
home
grounds
-father
Portgas
vertical
planted
pechay.
-ate Sakura
mopped the
floor with
disinfectanct
-mother
Tsaunade
sterilized
the
utensils
-threw
garbage
-kuya
Senku
bathed
Penduko
our dog
Sun 1/8/20
Portgas D. Ace
Sun 1/8/20
3. Keep your output in a safe place and send it on the exact date of submission to be
announced by your teacher.
6.3 Transport Mechanisms in Cells
6.4 Endocytosis vs. Exocytosis
What I Know
Write the letter of the best answer in the blank.
_____1. Which is not a part of the transport mechanisms in cells?
a. facilitated
b. active
c. osmosis
d. excytosis
_____2. What is the most direct form of transport mechanisms in cells?
a. passive
b. active
c. osmosis
d. excytosis
70
_____3. Hydrocarbons dissolve in the lipid bilayer, except for…
a. pass the membrane
b. hydrophobic
c. non polar
d. polar
_____4. Water molecules move from a region of high concentration to a region of
low concentration.
a. facilitated
b. active
c. osmosis
d. diffusion
_____5. Moves molecules from high to low regions of concentration with the
transmembrane protein
a. facilitated
b. active
c. osmosis
d. diffusion
Provide the right answers after the number in the boxes below for the difference
between Endocytosis and Exocytosis.
Definition
Process
Type
Vesicle
Endocytosis refers to the
transportation of macromolecules,
large particles, and polar
substances into the cell from the
external environment.
Exocytosis refers to….
6.
Involved with ….
7.
Involved in removing waste from
the cell
Occurs by ….
8.
Occurs by constitutive and
regulated secretory pathway
Internal vesicles like phagosomes
are formed
Forms….
9.
10.
Involved
11.
Releasing of hormones out of the
cell is an example
Cell Wall Formation
Example
71
What’s In
•
REVIEW: Transport Mechanisms in Cells (Diffusion, Osmosis,
Facilitated Transport, Active Transport) to its Function
Plasma membranes must allow certain substances to enter and leave a cell,
and prevent some harmful materials from entering and some essential materials
from leaving. In other words, plasma membranes are selectively permeable—they
allow some substances to pass through, but not others. If they were to lose this
selectivity, the cell would no longer be able to sustain itself, and it would be
destroyed. Some cells require larger amounts of specific substances. They must
have a way of obtaining these materials from extracellular fluids. This may happen
passively, as certain materials move back and forth, or the cell may have special
mechanisms that facilitate transport. Some materials are so important to a cell that it
spends some of its energy, hydrolyzing adenosine triphosphate (ATP), to obtain
these materials. Red blood cells use some of their energy doing just that. Most cells
spend the majority of their energy to maintain an imbalance of sodium and
potassium ions between the cell's interior and exterior, as well as on protein
synthesis.
The most direct forms of membrane transport are passive. Passive
transport is a naturally occurring phenomenon and does not require the cell to exert
any of its energy to accomplish the movement. In passive transport, substances
move from an area of higher concentration to an area of lower concentration. A
physical space in which there is a single substance concentration range has
a concentration gradient.
Selective Permeability
Plasma membranes lack symmetry: the membrane's exterior is not identical to
its interior (Fig. 7.h). There is a significant difference between the arrangement of
proteins and phospholipids and between the two leaflets that form a membrane. On
the membrane's interior, some proteins serve to anchor the membrane to
cytoskeleton's fibers. There are peripheral proteins on the membrane's exterior that
bind extracellular matrix elements. Carbohydrates, attached to lipids or proteins, are
also on the plasma membrane's exterior surface (Figure 7.b). These carbohydrate
complexes help the cell bind required substances in the extracellular fluid. This adds
considerably to plasma membrane's selective nature.
72
Fig. 7.h. molecular view of the cell membrane. Intrinsic proteins penetrate and bind tightly to the
lipid bilayer, which is made up largely of phospholipids and cholesterol and which typically is between
−9
4 and 10 nanometers (nm; 1 nm = 10 metre) in thickness. Extrinsic proteins are loosely bound to the
hydrophilic (polar) surfaces, which face the watery medium both inside and outside the cell. Some
intrinsic proteins present sugar side chains on the cell's outer surface. 2007 Encyclopædia Britannica,
Inc.
Fig. 7.i. Structural Component of Cellular Membrane
The plasma membrane's exterior surface is not identical to its interior surface.
Recall that plasma membranes are amphiphilic: They have hydrophilic and
hydrophobic regions. This characteristic helps move some materials through the
membrane and hinders the movement of others. Non-polar and lipid-soluble material
with a low molecular weight can easily slip through the membrane's hydrophobic lipid
core. Substances such as the fat-soluble vitamins A, D, E, and K readily pass
73
through the plasma membranes in the digestive tract and other tissues. Fat-soluble
drugs and hormones also gain easy entry into cells and readily transport themselves
into the body‘s tissues and organs. Oxygen and carbon dioxide molecules have no
charge and pass through membranes by simple diffusion.
Polar substances present problems for the membrane. While some polar
molecules connect easily with the cell's outside, they cannot readily pass through the
plasma membrane's lipid core. Additionally, while small ions could easily slip through
the spaces in the membrane's mosaic, their charge prevents them from doing so.
Ions such as sodium, potassium, calcium, and chloride must have special means of
penetrating plasma membranes. Simple sugars and amino acids also need the help
of various transmembrane proteins (channels) to transport themselves across
plasma membranes.
Key Takes of the Permeability of the Lipid Bilayer:
• Hydrophobic (nonpolar) molecules, such as hydrocarbons, can dissolve in the lipid
bilayer and pass through the membrane rapidly.
• Hydrophilic (Polar) molecules, such as sugars, do not cross the membrane easily.
Fig. 7.i. Substances highly impermeable to cross membrane like large uncharged polar molecules
(glucose and fructose), charged molecules and finally ALL IONS. But, Transport proteins are used to
transport ions across membrane.
74
The Transport Mechanisms
1. DIFFUSION
Passive movement of molecules from a region of high concentration to a region of
low concentration.
(Concentration gradient is the difference in concentration between the two
regions)
Small, uncharged molecules like O2, CO2 and H2O can move easily through the
membrane.
Works well over short distances. Once molecules enter the cell, the rate of
diffusion slows.
Limits cell size.
Fig. 7.j. Diffusion through a permeable membrane moves a substance from a high concentration area
(extracellular fluid, in this case) down its concentration gradient (into the cytoplasm).
2. OSMOSIS
Diffusion of the solvent across a semi-permeable membrane separating two
solutions. (Diffusion of water)
Water molecules move from a region of high concentration to a region of low
concentration.
Direction depends on the relative concentration of water molecules on either side
of the cell membrane.
Isotonic: Water inside the cell equals the water outside the cell and equal
amounts of water move in and out of the cell.
Hypotonic: Water outside the cell is greater than that inside the cell, water moves
into the cell, may cause cell to burst (lysis)
Hypertonic: Water inside the cell is greater than outside. Water moves out of the
cell, may cause the cell to shrink (plasmolysis)
75
Fig. 7.k. Movement of water molecules from high concentration to low concentration, through a semipermeable membrane.
3. FACILITATED TRANSPORT (ALSO KNOWN AS FACILITATED DIFFUSION OR
PASSIVE-MEDIATED TRANSPORT)
Assists with the movement of large molecules like glucose.
Passive movement of a substance into or out of the cell by means of carrier
proteins or channel proteins.
Moves molecules from high to low regions of concentration.
Carrier proteins: Transports noncharged molecules with a specific shape.
Channel proteins: Tunnel shape that transports small charged molecules.
DOES NOT REQUIRE water molecules for other molecules to transfer.
Fig. 7.l. Facilitated diffusion in cell membrane, showing ion channels and carrier proteins.
76
4. ACTIVE TRANSPORT
The process of moving substances against their concentration gradients
Requires Energy.
Examples:
Kidney cells pump glucose and amino acids out of the urine and
back into the blood.
Intestinal cells pump in nutrients from the gut.
Root cells pump in nutrients from the soil.
Gill cells in fish pump out sodium ions.
Fig. 7.m. Active transport: Requires the use of chemical energy to move substances across a
membrane, against a concentration gradient. Active transport proteins may be uniports, symports, or
antiports.
Active Transport Pump:
Sodium-potassium pump
3 sodium ions inside the cell and 2 potassium ions outside the cell bind to
the pump.
This allows the release of energy from ATP and causes the protein
complex to change shape.
The change in shape allow the Na+ and K+ ions to move across and be
released.
77
Fig. 7.n. In Primary active transport, energy from the hydrolysis of ATP is used to move ions into or
out of cells against their concentration gradients. The sodium-potassium pump is an important
example.
Fig. 7.o. Secondary active transport couples the passive movement of one substance with its
concentration gradient to the movement of another substance against its concentration gradient.
Energy from ATP is used indirectly to establish the concentration gradient that results in the
movement of the first substance.
78
5. BULK TRANSPORT
1. Endocytosis: The cell membrane folds inward, traps and encloses a small
amount of matter from the extracellular fluid.
2. Exocytosis: The reverse of endocytosis: A vesicle from inside the cell moves to
the cell membrane. The vesicle fuses to the membrane and the contents are
secreted.
Fig. 7.p. Exocytosis and Endocytosis
Difference between Endocytosis and Exocytosis
Definition
Endocytosis refers to
the transportation of
macromolecules, large
particles, and polar
substances into the cell
from the external
environment
Process
Involved with up taking
nutrients into the cell
Involved in removing
waste from the cell
Type
Occurs by both
phagocytosis and
pinocytosis
Occurs by constitutive
and regulated secretory
pathway
79
Exocytosis refers to the
transportation of
molecules or particles
from the cell to the
outside of the cell
Vesicle
Internal vesicles like
phagosomes are formed
Secretory vesicles are
formed
Cell Wall
Formation
Not involved
Involved
Example
Engulfing bacteria by
phagocytes is an
example
Releasing of hormones
out of the cell is an
example
3 Types of Endocytosis:
Pinocytosis: The intake of a small droplet of extracellular fluid. This occurs in
nearly all cell types.
Phagocytosis: The intake of a large droplet of extracellular fluid. This occurs in
specialized cells.
Receptor-assisted endocytosis: The intake of specific molecules that attach to
special proteins in the cell membrane. These proteins are uniquely
shaped to fit the shape of a specific molecule.
Fig. 7.q. Secondary active transport couples the passive movement of one substance with its
concentration gradient to the movement of another substance against its concentration gradient.
Energy from ATP is used indirectly to establish the concentration gradient that results in the
movement of the first substance.
80
What’s New
•
Visual and Listening Activity:
1. A video link is provided ; ―Cell Transport‖ by Amoeba Sisters (2016),
https://www.youtube.com/watch?v=Ptmlvtei8hw
2. Watch and Listen carefully for you to be able to determine and differentiate the
types of transport mechanism in a cell.
3. Make a reaction paper of the video clip.
4. Write it on a long bond paper.
What Is It
•
Q & A Activity:
1. Why is the transport mechanism vital in a cell?
2. How are things transported through the membrane?
3. How will a person know if the transport mechanism in the cell throughout our body
is starting not to work not working?
4. What will you compare to the transport mechanism to what we have today?
5. If you are to choose what transport mechanism you prefer, what will it be and
why?
What’s More
•
Crafting Activity:
1. Choose one (1) Transport Mechanism in a cell and make a relatable analogy
based on your experience recently.
2. Illustrate and explain your work on a long bond paper .
81
3. Write your sketch neatly on a long bond paper.
4. Keep your output in a safe place and submit it on the exact date of submission to
be announced by your teacher.
What I Have Learned
•
Q & A Activity:
1. Provide the different Transport Mechanisms in a cell with at least 2-3 attributes.
2. How are things transported through the membrane?
3. How will a person know if the transport mechanism in the cell throughout our body
is starting not to work not working?
4. What will you compare to the transport mechanism to what we have today?
5. If you are to choose what transport mechanism you prefer, what will it be and
why?
What I Can Do
•
Performance Activity:
1. Choose what you think will be the Transport Mechanism you need to create a
story that reflects what our country is experiencing now.
2. Write your draft on a piece of paper and after you‘re done, transfer it in a long
bond paper .
3. Keep your output in a safe place and submit it on the exact date of submission to
be announced by your teacher.
82
Assesment
Write the letter of the best answer in the blank.
_____1. What is the primary function of carbohydrates attached to the exterior of cell
membranes?
a. identification of the cell
b. flexibility of the membrane
c. strengthening the membrane
d. channels through membrane
_____2. Which plasma membrane component can be either found on its surface or
embedded in the membrane structure?
a. protein
b. cholesterol
c. carbohydrate
d. phospholipid
_____3. Carbohydrates is found outside the surface of the cell and bounded with?
a. lipid or protein
b. phospholipid
c. glycoprotein
d. glycolipid
_____4. Which interacts to hydrophilic and hydrophobic environments?
a. protein
b. cholesterol
c. phospholipid
d. carbohydrate
_____5. Which characteristic of a phospholipid contributes to the fluidity of the
membrane?
a. its head
b. cholesterol
c. a saturated fatty acid tail
d. double bonds in the fatty acid tail
_____6. What is the primary function of carbohydrates attached to the exterior of cell
membranes?
a. identification of the cell
b. flexibility of the membrane
c. strengthening the membrane
d. channels through membrane
83
_____7. The primary function of the plasma membrane is ….
a. to protect the cell from its surroundings.
b. to provide shape and integrity to the cell.
c. to maintains the cell potential.
d. to be a fluid mosaic model.
_____8. Vital for cellular signalling processes that influence tissue and organ
formation
a. membrane markers
b. membrane receptors
c. glycoprotein
d. glycolipid
_____9. Cellular Transport Mechanism‘s relation to the Plasma Membrane is…
a. to protect intracellular components from the extracellular environment.
b. to transport materials into or out of the cell
c. to enclose and define the borders of the cell
d. to transmit signals via complex proteins
_____10. Cellular Signaling relation to the Plasma Membrane is….
a. to protect intracellular components from the extracellular environment.
b. to enclose and define the borders of the cell
c. to transmit signals via complex proteins
d. to transport materials into or out of the cell
_____11. Hydrocarbons dissolve in the lipid bilayer, except for…
a. pass the membrane
b. hydrophobic
c. non polar
d. polar
_____12. Which is not a part of the transport mechanisms in cells?
a. facilitated
b. active
c. osmosis
d. excytosis
_____13. What is the most direct form of transport mechanisms in cells?
a. passive
b. active
c. osmosis
d. excytosis
_____14. Water molecules move from a region of high concentration to a region of
low concentration.
a. facilitated
b. active
c. osmosis
d. diffusion
84
_____15. Moves molecules from high to low regions of concentration with the
transmembrane protein
a. facilitated
b. active
c. osmosis
d. diffusion
_____16. All are attributes of exocytosis except for…
a. Involved with up taking nutrients into the cell
b. Secretory vesicles are formed
c. Involved in removing waste from the cell
d. Uninvolved in cell Wall Formation
_____17. Water inside the cell equals the water outside the cell and equal
amounts of water move in and out of the cell.
a. Osmotic
b. Hypertonic
c. Hypotonic
d. Isotonic
_____18. Mechanism using ATP
a. facilitated
b. active
c. osmosis
d. excytosis
_____19. Engulfment involves…
a. passive
b. active
c. endocytosis
d. excytosis
_____20. Waste removal involves….
a. passive
b. active
c. endocytosis
d. excytosis
85
Lesson
Structures and Functions of
Biological Molecules
- Enzymes
7
What I Need to Know

Learning Competencies:
1. Describe the components of an enzyme (STEM_BIO11/12-Ii-j-17)
2. Explain oxidation/reduction reactions (STEM_BIO11/12-Ii-j-18)
3. Determine how factors such as pH, temperature, and substrate affect
enzyme activity (STEM_BIO11/12-Ii-j-19)

Performance Standards:
The learners should be able to construct a cell membrane model
from indigenous or recyclable materials.

Introduction:
When you were very young and played under the heat of the sun, were
you able to experience sweat dripping in your neck, head and then like
some acid that went in your eyes, it feels burning and stingy right? But don‘t
you worry. Now, we all know that the burning and stingy sensation in our
eyes was due to dust and oils that came in contact with the sweat and to an
anti-microbial enzyme fighting off germs called Lysozyme.
So enzymes are vital for life and serve a wide range of important
functions in the body, such as aiding in fighting germs, digestion, and
metabolism.
86
Some enzymes help break large molecules into smaller pieces that are
more easily absorbed by the body. Other enzymes help bind two molecules
together to produce a new molecule. Enzymes are highly selective
catalysts, meaning that each enzyme only speeds up a specific reaction.
Peeling, bruising, or cutting fruits cause them to release enzymes like
polyphenol oxidase (PPO, phenolase) that, with the presence of oxygen
(oxidation) in the surrounding air, goes into chemical reactions of plant
compounds. These chemical reactions produce brown pigments through
the process of enzymatic browning (Fig. 8.a.)
Oxidation and reduction occur in tandem and it occurred when peeling
or cutting fruits resulting to an enzymatic browning. Because oxidation and
reduction usually occur together, these pairs of reactions are called
oxidation reduction reactions, or redox reactions.
Think of people passing balls back and forth, and the balls are balls of
negativity. So if I'm holding the ball, I'm reduced. If I pass you the ball, you
get reduced, and I become oxidized. The passing of the ball was the
reduction-oxidation reaction.
An oxidation-reduction (redox) reaction is a type of chemical reaction that
involves a transfer of electrons between two species. An oxidationreduction reaction is any chemical reaction in which the oxidation number
of a molecule, atom, or ion changes by gaining or losing an electron. A
classic example of a redox reaction is rusting. When rusting happens,
oxygen steals electrons from iron. Oxygen gets reduced while iron
gets oxidized.
Fig. 8.a. Enzymatic browning of a sliced apple.
87
7.1 Transport Mechanisms in Enzymes
What I Know
Write the letter of the best answer in the blank.
_____1. Where the reaction is catalysed in an enzyme?
a. Facilitated site
b. Active site
c. Passive site
d. Direct site
_____2. Catalyze group transfer reactions; often require coenzymes.
a. Transferases
b. Hydrolases
c. Lyases
d. Isomerases
_____3. Lysis of substrate; produce contains double bond.
a. Transferases
b. Hydrolases
c. Lyases
d. Isomerases
_____4. Enzymes are described as all of the above except
a. micromolecule
b. macromolecule
c. stereospecific
d. having a defined amino acid sequence
_____5. Active forms from one of the inactive enzyme .
a. Apoenzyme
b. Holoenzyme
c. Cofactor
d. Coenzyme
_____6. Enzymes described having a typically long amino acid sequence about?
a. 100-400
b. 100-500
c. 100-600
d. 100-700
PRIOR KNOWLEDGE: Definition of Terms
7. Catalyst
8. Active Side
9. Enzyme
10. Substrate
88
What’s In
•
REVIEW: Description of the Components of Enzyme
What is an enzyme?


Enzymes are protein macromolecules.
o They have a defined amino acid sequence, and are typically 100-500
amino acids long.
o They have a defined three-dimensional structure.
Enzymes are catalysts.
o They act as a catalyst to a chemical or biochemical reaction, with a
defined mechanism.
6
14
o They increase the speed of that reaction, typically by 10 -10 times
faster than the rate of the uncatalysed reaction.
o They are selective for a single substrate.
o They speed up rate of reaction by lowering the activation energy (Ea).
o They are stereospecific, meaning the reaction produces a single
product.
Common mistakes and misconceptions

Enzymes are "specific." Each type of enzyme typically only reacts with one
(Fig 8.b.), or a couple, of substrates. Some enzymes are more specific than
others and will only accept one particular substrate. Other enzymes can act
on a range of molecules, as long as they contain the type of bond or chemical
group that the enzyme targets.
Fig. 8.b. A substrate entering the active site of the enzyme.
Image modified from "Enzymes: Figure 2," by OpenStax College, Biology, CC BY 3.0.
.
89

Enzymes are reusable. Enzymes are not reactants and are not used up
during the reaction. Once an enzyme binds to a substrate and catalyzes the
reaction, the enzyme is released, unchanged, and can be used for another
reaction. This means that for each reaction, there does not need to be a 1:1
ratio between enzyme and substrate molecules.
Nomenclature
Typically add “-ase” to name of substrate
e.g. lactase breaks down lactose (dissacharide of glucose and galactose)
Enzymes based upon the class of organic chemical reaction catalyzed:
1. Oxidoreductase - catalyze redox reactions; dehydrogenases, oxidases,
peroxidases, reductases.
2. Transferases - catalyze group transfer reactions; often require coenzymes.
3. Hydrolases - catalyze hydrolysis reactions.
4. Lyases - lysis of substrate; produce contains double bond.
5. Isomerases - catalyze structural changes; isomerization.
6. Ligases - ligation or joining of two substrates with input of energy, usually from
ATP hydrolysis; often called synthetases or synthases.
ENZYME COMPONENTS (Fig. 8.c.)
•
Apoenzyme:
• is an inactive enzyme, activation of the enzyme occurs upon binding of an
organic or inorganic cofactor.
• are enzymes that lack their necessary cofactor(s) for proper functioning
• a Protein
•
•
•
•
•
•
•
•
•
Holoenzyme: (Fig. 8.d.)
are the active forms of apoenzymes. (Apoenzyme plus cofactor)
DNA polymerase and RNA polymerase are examples.
Cofactor:
mostly metal ions or small organic molecules, are inorganic and organic
chemicals that assist enzymes during the catalysis of reactions.
Nonprotein component (e.g. magnesium, zinc)
Coenzyme:
are non-protein organic molecules that are mostly derivatives of vitamins
soluble in water by phosphorylation
Organic cofactor (Eg: NADH, FADH)
Many enzymes can catalyze a reaction only if coenzymes, or cofactors are present.
90
Fig. 8.c. Parts of an Enzyme
Fig. 8.d. Component of a Holoenzyme
Terminology:
Catalyst

A substance that speeds up a chemical reaction without being changed

A biological catalyst (usually a protein)
Enzyme
Substrate

The reactant molecule that an enzyme works on
Active Site
 The part of the enzyme where the substrate binds
Enzyme-substrate complex
 formed when the substrate molecule collides with the active site of its
enzyme
Endoenzymes(intracellular) / Exoenzymes (extracellular)
91
Activation energy
 the minimum energy required to start a chemical reaction
Transition state
 the intermediate stage in a reaction in which the old bonds break and
new bonds are formed
What’s New
•
Visual and Listening Activity:
1. A video link is provided ; ―Cofactors | Coenzymes | Holoenzyme | Apoenzyme,
QuickBiochemistry Basics (2020),
https://www.youtube.com/watch?v=LK5HzcAOmyA
2. Watch and Listen carefully to the video and be able to recognize the components
of enzyme.
3. Make a descriptive reaction paper emphasizing the components of the enzyme.
4. Write it neatly on a long bond paper.
What Is It
•
Q & A Activity:
1. What are the components of the enzyme that makes it important or vital?
2. How does the component or part of the enzyme contribute to its function?
3. What are each of the components attributes? Describe them.
(Write your answers on a ½ crosswise intermediate paper.)
92
What’s More
•
Visual and Listening Activity:
1. Watch the video clip ―How Enzymes Work‖, RicochetScience (2015),
https://www.youtube.com/watch?v=UVeoXYJlBtI .
2. The video is explaining the mechanism of an enzymatic activity. But with the
image below, relate what you have learned and try to explain what is happening
from #1 - #5.
3. Draw and label with your best answer on a long coupon bond.
What I Have Learned
•
Learning Process Activity:
Write T if the statement is true and F if the statement is false.
______1. Substrate binds in the active site.
______2. An enzyme is usually lipid biological catalyst.
______3. The reactant molecule that an enzyme works on is the Substrate.
______4. A Catalyst retards the chemical reaction without being changed
______5. Coenzymes are non-protein organic molecules that are mostly derivatives
of vitamins
______6. Cofactors are small protein organic molecules that assist enzymes during
the catalysis of reactions.
______7. DNA and RNA polymerases are examples of Holoenzyme.
93
______8. Apoenzyme activation occurs upon binding of an organic or inorganic
coenzyme.
______9. Enzymes are reactants and are used up during the reaction.
______10. Once an enzyme binds to a substrate and catalyzes the reaction, the
enzyme is released, unchanged, and can be used for another reaction.
______11. Some enzymes are more specific than others and will only accept one
particular substrate
______12. Enzymes have a defined two-dimensional structure.
______13. Enzyme‘s amino acid sequence are typically 10-500 amino acids long.
______14. Transition state is the intermediate stage in the enzymatic mechanism.
______15. Substrate molecule collides with the active site of its enzyme forms the
Enzyme Substrate complex.
What I Can Do
•
Performance Activity:
1. Life is hard nowadays; you‘re supposed to be able to know how to cook since
you‘re already a Senior High student. You can ask your guardian or parents to help
you with your dish. Choose a recipe that you can easily cook. Only do this at home if
you‘re permitted to do so.
2. Prepare your ingredients and materials for the activity and document everything
using the camera of your phone or just list them down.
3. Write and determine your ingredients that will represent most likely the component
of an enzyme. Describe the process of your activity like what would be the catalyst in
your ingredients that sped up the reaction to make the finished product or what your
salt would be represent in the components.
4. After you‘re done baking or cooking with the assistance of your parent or guardian
(photos required if possible), reflect on all of the resources that you‘re able to utilize
and appreciate them by serving your dish (output) first to your family and consume
them together taken with a groufie pic.
5. Document everything from preparing to cooking and serving on a long bond and
secure it until the date of submission that will be announced by the teacher.
94
7.2 Oxidation/Reduction Reactions
What I Know
PRIOR KNOWLEDGE: Definition of Terms
1. Oxidation
2. Reduction
3. Oxidants
4. Reductants
5. Reagent
What’s In

REVIEW: Oxidation-Reduction Reactions
An oxidation-reduction (redox) reaction is a type of chemical reaction that
involves a transfer of electrons between two species. An oxidation-reduction reaction
is any chemical reaction in which the oxidation number of a molecule, atom, or ion
changes by gaining or losing an electron. Redox reactions are common and vital to
some of the basic functions of life, including photosynthesis, respiration, combustion,
and corrosion or rusting.
• oxidation-reduction reactions are also called REDOX reactions
• all redox reactions involve the transfer of electrons from one atom to another
• spontaneous redox reactions are generally exothermic, and we can use their
released energy as a source of energy for other applications.
Redox reactions are comprised of two parts, a reduced half and an oxidized half,
that always occur together. The reduced half gains electrons and the oxidation
number decreases, while the oxidized half loses electrons and the oxidation number
increases. Simple ways to remember this include the mnemonic devices OIL
RIG, meaning "oxidation is loss" and "reduction is gain," and LEO says
GER, meaning "loss of e- = oxidation" and "gain of e- = reduced." There is no net
change in the number of electrons in a redox reaction. Those given off in the
oxidation half reaction are taken up by another species in the reduction half reaction.
A good example of a redox reaction is the thermite reaction, in which iron atoms
in ferric oxide lose (or give up) O atoms to Al atoms, producing Al 2O3.
Fe2O3(s)+2Al(s)→Al2O3(s)+2Fe(l)
95
What do you mean by oxidation and reduction?
• OXIDATION can be defined as addition of oxygen/electronegative element to a
substance or removal of hydrogen/ electropositive element from a substance.
• REDUCTION can be defined as removal of oxygen/electronegative element from a
substance or addition of hydrogen/ electropositive element to a substance.
*oxidation occurs when an atom’s oxidation
state increases during a reaction
*reduction occurs when an atom’s oxidation
state decreases during a reaction
Development of oxidation and reduction reaction concept______________________
Reaction of reduction oxidation based on releasing (losing) and gaining of oxygen (capturing).
a. Oxidation reaction is a reaction of gaining (capturing) of oxygen by a substance
Ex.
CH4(g) + 2O2(g)  CO2(g) + 2H2O(g)
P4(s) + 5O2(g)  2P2O5(s)
b. Reduction reaction is a reaction of releasing (losing) of oxygen from an oxide
compound
Ex.
CuO(s) + H2(g)  Cu(s) + H2O(g)
Fe2O3(s) + 3CO(g)  2Fe(s) + 3CO2(g)
What is an oxidizing and reducing agent?
• Oxidizing agent: a reagent which increases the oxidation number of an element of
a given substance. These reagents are called oxidants. It contains the element that
is reduced.
• Reducing agent: a reagent that lowers the oxidation number of a given element.
These reagents are also called reductants. It contains the element that is oxidized.
2 Na(s) + Cl2(g)  2 Na+Cl–(s)
Na is oxidized, Cl is reduced
Na is the reducing agent, Cl2 is the oxidizing agent
96
Terminology:
Reactant
 is a substance or compound added to a system to cause a chemical reaction, or
added to test if a reaction occurs. The terms reactant and reagent are often used
interchangeably—however, a reactant….
Reagent
 is more specifically a substance consumed in the course of a chemical reaction.
What’s New
•
Visual and Listening Activity:
1. A video link is provided ; ―Introduction to Oxidation Reduction (Redox) Reactions‖,
Tyler DeWitt (2015), https://www.youtube.com/watch?v=5rtJdjas-mY
2. Watch and Listen carefully to the video and be able to understand REDOX
reaction.
3. Make a detailed reaction paper explaining the REDOX reaction. Provide 3
examples.
4. Write it neatly on a long bond paper.
What Is It
•
Q & A Activity:
1. What are the components that make up REDOX reaction?
2. Who gains and losses electrons?
3. When does REDOX reaction happens?
4. Why is REDOX significant to learn?
(Write your answers on a ½ crosswise intermediate paper.)
97
What I Have Learned
•
Learning Process Activity:
Write the letter of the best answer in the blank.
_____1. A substance consumed in the course of a chemical reaction.
a. Reactant
b. Reagent
c. Reductant
d. Oxidant
_____2. Substance added to test if a reaction occurs.
a. Reactant
b. Reagent
c. Reductant
d. Oxidant
_____3. Contains the element that is oxidized..
a. Reactant
b. Reagent
c. Reductant
d. Oxidant
_____4. Contains the element that is reduced.
a. Reactant
b. Reagent
c. Reductant
d. Oxidant
_____5. Occurs when an atom‘s oxidation state decreases during a reaction.
a. Oxidation
b. Reduction
c. Reduction-Oxidation Reaction
d. All are correct.
_____6. Occurs when an atom‘s oxidation state increases during a reaction.
a. Oxidation
b. Reduction
c. Reduction-Oxidation Reaction
d. All are correct.
_____7. Oxidizing agent lowers the oxidation number of a given element.
a. True
b. False
98
_____8. True to oxidation-reduction (redox) reaction. Except…
a. OXIDATION can be removal of hydrogen/ electropositive element from a
substance.
b. REDUCTION can be removal of oxygen/electronegative element from a
substance.
c. Spontaneous redox reactions are generally endothermic.
d. All redox reactions involve the transfer of electrons from one atom to another.
7.3 Determining the Factors Affecting Enzyme Activity
What I Know
Place the letters of the best answer inside the box of the factor icon which influences
the activity of the enzyme.
1.
A. Changing this factor outside the enzyme‘s optimum
range will slow enzyme activity.
B. Decreasing this factor slows down a reaction
2.
C. This factor at an optimum pH, near neutral causes
enzymes to catalyze a reaction most rapidly.
D. Increasing this factor will speed up the reaction,
as long as there is substrate available to bind to.
3.
E. At the saturation point, the reaction will not speed up, no
matter how much of this factor is added.
4.
F. Increasing this factor can cause an enzyme to lose its
shape (denature) and stop working.
G. Increasing this factor, the greater should be the initial reaction
rate and will last as long as substrate present.
H. This factor‘s graph of the reaction rate will plateau.
99
What’s In

REVIEW: Factors Affecting Enzyme Activity
Enzyme activity can be affected by a variety of factors, such as temperature, pH,
concentrations and inhibitors.
Enzymes work best within specific temperature and pH ranges, and sub-optimal
conditions can cause an enzyme to lose its ability to bind to a substrate.
Determnants of the Factors Affecting Enzyme Activites
A. Temperature: Raising temperature generally speeds up a reaction, and
lowering temperature slows down a reaction. However, extreme high
temperatures can cause an enzyme to lose its shape (denature) and stop
working. Most enzymes have an optimum temperature, near normal body
temperature at which they catalyze a reaction most rapidly.
B. pH (abbr. power of hydrogen or potential for hydrogen ): Each enzyme has an
optimum pH range. Changing the pH outside of this range will slow enzyme
activity. Extreme pH values can cause enzymes to denature. Even small pH
changes can alter the electrical charges on various chemical groups in
enzyme molecules, thereby altering the enzyme‘s ability to bind its substrate
and catalyze a reaction.
100
Enzymes catalyze a reaction most rapidly at an optimum pH, near neutral.
C. Substrateoconcentration: Increasing substrate concentration also increases
the rate of reaction to a certain point. Once all of the enzymes have bound,
any substrate increase will have no effect on the rate of reaction, as the
available enzymes will be saturated and working at their maximum rate. At the
saturation point, the reaction will not speed up, no matter how much additional
substrate is added. The graph of the reaction rate will plateau.
D. Enzyme concentration: Increasing enzyme concentration will speed up the
reaction, as long as there is substrate available to bind to. Once all of the
substrate is bound, the reaction will no longer speed up, since there will be
nothing for additional enzymes to bind to.
101
The higher the concentration of an enzyme the greater should be the initial
reaction rate. This will last as long as substrate present
E. Enzyme Inhibitors (Inhibition):
o
Competitive inhibitor: A molecule similar in structure to a substrate
can bind to an enzyme‘s active site and compete with substrate
102
o
Noncompetitive inhibitors: attach to the enzyme at an allosteric
site, which is a site other than the active site distort the tertiary protein
structure and alter the shape of the active site.
103
o
Feedback inhibition: regulates the rate of many metabolic pathways
when an end product of a pathway accumulates and binds to and
inactivates the first enzyme in the metabolic pathway. Product (usually
ultimate product) of a pathway controls the rate of synthesis through
inhibition of an early step (usually the first step). Conserves material
and energy by preventing accumulation of intermediates.
104
What’s New
•
Visual and Listening Activity:
1. 2 video links are provided ; “ GCSE Biology - How Enzymes Work #11‖ and
―GCSE Biology - Factors that Affect Enzymes #12‖ by Cognito (2018),
Part 1: https://www.youtube.com/watch?v=VNX9UQ08fZ4
Part 2: https://www.youtube.com/watch?v=qq1foXnvJao
2. Watch and Listen carefully to the video and be able to recognize and relate to
each factors affecting the enzymatic activities.
3. Make a detailed reaction paper regarding the video clip yousaw.
4. Write your reaction on a long bond paper.
What Is It
•
Q & A Activity:
1. What are factors involved in the enzymatic activity?
2. How can you determine the effects of each factor of the enzymatic activity?
3. Select 1 factor that most likely reflects your life as a Senior High student.
(Write your answers on a 1 whole intermediate paper.)
What I Have Learned
•
Learning Process Activity:
Provide the best answer in the blank.
1. __________ regulates the rate of many metabolic pathways.
2. __________ attach to the enzyme at an allosteric site.
3. __________ can bind to an enzyme‘s active site and compete with substrate.
4. __________ is a place on an enzyme where a molecule that is not a substrate
may bind.
105
Enzyme activity can be affected by a variety of factors, such as 5. __________,
6. __________, 7. __________, 8. __________, and 9. __________.
10. Evidently the graph on a substrate concentration will present a __________.
What I Can Do
•
Performance Activity:
Grow a plant.
A plant can represent an enzyme while your water, soil and sunlight can represent
the substrates. Guess what the inhibitors can represent? Maybe anything that will
negatively affect the plant like not watering it on schedule, not getting enough
sunlight and so much more. We know the byproducts of the plants that are well
taken care of, right? Food and oxygen, or something beneficial to us.
1. Gather a recyclable container like cola bottles, loam soil, fertilizer, etc. Use tools
needed like a small shovel or trowel for transferring the soil inside the container.
3. Decide on a plant you want to easily take care and be beneficial for your
household. Then, secure the seeds or graft of the plant you decided on. Plant it.
4. Document everything for a month (photos included if possible), starting from the
first day of listing down the materials and recording the plant‘s growth in centimeters.
Keep a record notebook for the schedule of submission.
..
Assesment
Write the letter of the best answer in the blank.
_____1. Catalyze group transfer reactions; often require coenzymes.
a. Transferases
b. Hydrolases
c. Lyases
d. Isomerases
_____2. Where the reaction is catalysed in an enzyme?
a. Facilitated site
b. Active site
c. Passive site
d. Direct site
106
_____3. Lysis of substrate; produce contains double bond.
a. Transferases
b. Hydrolases
c. Lyases
d. Isomerases
_____4. True to temperature as a factor of enzymatic reaction.
a. This factor at an optimum level, near neutral, causes enzymes to catalyze a
reaction most rapidly.
b. Changing this factor outside the enzyme‘s optimum range will slow enzyme
activity.
c. At the saturation point, the reaction will not speed up, no matter how much of
this factor is added.
d. Increasing this factor can cause an enzyme to lose its shape (denature) and
stop working.
_____5. Enzymes are described as all of the above except
a. micromolecule
b. macromolecule
c. stereospecific
d. having a defined amino acid sequence
_____6. Active forms from one of the inactive enzyme .
a. Apoenzyme
b. Holoenzyme
c. Cofactor
d. Coenzyme
_____7. Enzymes described having a typically long amino acid sequence about?
a. 100-400
b. 100-500
c. 100-600
d. 100-700
_____8. Occurs when an atom‘s oxidation state decreases during a reaction.
a. Oxidation
b. Reduction
c. Reduction-Oxidation Reaction
d. All are correct.
_____9. Contains the element that is oxidized..
a. Reactant
b. Reagent
c. Reductant
d. Oxidant
107
_____10. All the statements are not true to the substrate concentration, except for...
a. This factor at an optimum level, near neutral, causes enzymes to catalyze a
reaction most rapidly.
b. Changing this factor outside the enzyme‘s optimum range will slow enzyme
activity.
c. At the saturation point, the reaction will not speed up, no matter how much of
this factor is added.
d. Increasing this factor can cause an enzyme to lose its shape (denature) and
stop working.
_____11. Substance added to test if a reaction occurs.
a. Reactant
b. Reagent
c. Reductant
d. Oxidant
_____12. Occurs when an atom‘s oxidation state increases during a reaction.
a. Oxidation
b. Reduction
c. Reduction-Oxidation Reaction
d. All are correct.
_____13. Oxidizing agent lowers the oxidation number of a given element.
a. True
b. False
_____14. True to oxidation-reduction (redox) reaction. Except…
a. OXIDATION can be removal of hydrogen/ electropositive element from a
substance.
b. REDUCTION can be removal of oxygen/electronegative element from a
substance.
c. Spontaneous redox reactions are generally endothermic.
d. All redox reactions involve the transfer of electrons from one atom to another.
_____15. A substance consumed in the course of a chemical reaction.
a. Reactant
b. Reagent
c. Reductant
d. Oxidant
_____16. Regulates the rate of many metabolic pathways.
a. Feedback inhibition
b. Noncompetitive inhibitors.
c. Competitive inhibitor.
d. Substrate Concentration
108
_____17. Can bind to an enzyme‘s active site and compete with substrate.
a. Feedback inhibition
b. Noncompetitive inhibitors.
c. Competitive inhibitor
d. Substrate Concentration
_____18. Contains the element that is reduced.
a. Reactant
b. Reagent
c. Reductant
d. Oxidant
_____19. Attach to the enzyme at an allosteric site
a. Feedback inhibition
b. Noncompetitive inhibitors
c. Competitive inhibitor
d. Substrate Concentration
_____20. True to pH, except for...
a. This factor at an optimum level, near neutral, causes enzymes to catalyze a
reaction most rapidly.
b. Changing this factor outside the enzyme‘s optimum range will slow enzyme
activity.
c. At the saturation point, the reaction will not speed up, no matter how much of
this factor is added.
d. Increasing this factor can cause an enzyme to lose its shape (denature) and
stop working.
109
Disorders and Diseases that Result from the
Malfunction of the Cell during the Cell Cycle
What I Know
1b
2a
3d
4a
5c
What I Have Learned
1. Down Syndrome
2.Klinefelter syndrome
3.Patau syndrome and
4.Cri du chat syndrome
5. Aneuploidy
6. Leukemia
7. 90%
8. egg formation
9. sperm formation
10. cancer cell
7.1 Structural Components of the Cell
Membrane
What I Know
1a
2a
3d
4c
5a
6 are amphipathic molecules
7 Tucked between the hydrophobic tails of the
membrane phospholipids
8 Transport of substance through membrane
9 Cell recognition
10 Attached to proteins or lipids on the
extracellular side of the membrane
What I Have Learned
1. fluid mosaic model , fluid mosaics of lipids and
proteins
2 phospholipids
3 Carbohydrates
4 To identify the cell to other cells
5 temperature
6 enclose, define
7 Membrane transport
8 Integral Protein
110
7.2 The Relationship of the Structure and
Composition of the Cell Membrane to its
Function
What I Know
1a
2a
3c
4b
5a
6 protect the cell from its surroundings
7 allow cells to recognize one another
8 provide shape and integrity to the cell
9 transports small organic molecules
10 provide extracellular attachment sites
What‘s New
1 glycoprotein
2 glycolipid
3 peripheral membrane
4 integral membrane
5 cytoskeletal filaments
6 cholesterol
7 protein channel
8 phopsolipid bilayer
7.3 Transport Mechanisms in Cells
7.4 Endocytosis vs. Exocytosis
What I Know
1d
2a
3d
4c
5a
6 Exocytosis refers to the transportation of
molecules or particles from the cell to the outside
of the cell
7 Involved with up taking nutrients into the cell
8 Occurs by both phagocytosis and pinocytosis
9 Secretory vesicles are formed
10 Not involved
11 Engulfing bacteria by phagocytes
ANSWER KEY
7 Assesment
1a
2a
3a
4c
5d
6a
7a
8a
9b
10c
11d
12d
13a
14c
15a
16a
17d
18b
19c
20d
8.1 Components of an Enzyme
What I Know
1b
2a
3c
4a
5b
6b
7 A substance that speeds up a chemical
reaction without being changed
8 The part of the enzyme where the substrate
binds
9 A biological catalyst (usually a protein)
10The reactant molecule that an enzyme works
on
What I have Learned
1T
11T
2F
12F
3T
13F
4F
14T
5T
15T
6F
7T
8F
9F
10T
111
8.2 Oxidation/Reduction Reactions
What I Know
1 addition of oxygen/electronegative element to a
substance or removal of hydrogen/
electropositive element from a substance
2 removal of oxygen/electronegative element
from a substance or addition of hydrogen/
electropositive element to a substance
3 reagent which increases the oxidation number
of an element of a given substance
4 a reagent that lowers the oxidation number of a
given element
5 a substance consumed in the course of a
chemical reaction
What I Have Learned
1b
2a
3c
4d
5b
6a
7b
8c
8.3 Determining the Factors Affecting Enzyme
Activity
What I Know
1 b,f
2 a,c
3 e,h
4 d,g
What I have Learned
1 Feedback inhibition
2Noncompetitive inhibitors
3Competitive inhibitor
4Allosteric site
5temperature,
6pH,
7enzyme concentrations
8substrate concentrations
9 inhibitors
10plateau
ANSWER KEY
112
8 Assesment
1a
2b
3c
4d
5a
6b
7b
8b
9c
10c
11a
12a
13b
14c
15b
16a
17c
18d
19b
20a
ANSWER KEY
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