MCAS Review
Cell Biology
Simple or Complex
Cells
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Prokaryotes – The first Cells
• Cells that lack a nucleus or membranebound organelles
• Includes bacteria
• Simplest type of cell
• Single, circular chromosome
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Prokaryotes
• Nucleoid region (center)
contains the DNA
• Surrounded by cell
membrane & cell wall
(peptidoglycan)
• Contain ribosomes (no
membrane) in their
cytoplasm to make
proteins
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Eukaryotes
• Cells that HAVE a nucleus
and membrane-bound
organelles
• Includes protists, fungi,
plants, and animals
• More complex type of cells
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Two Main Types of Eukaryotic
Cells
Plant Cell
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Animal Cell
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Animal Cell Organelles
Ribosome (attached)
Ribosome (free)
Nucleolus
Nucleus
Cell Membrane
Nuclear envelope
Mitochondrion
Smooth
endoplasmic
reticulum
Rough
endoplasmic
reticulum
Centrioles
Golgi apparatus
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Plant Cell Organelles
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Cell or Plasma Membrane
• Composed of double layer of phospholipids and
proteins
• Surrounds outside of ALL cells
• Controls what enters or leaves the cell
• Living layer
Outside
of cell
Proteins
Carbohydrate
chains
Cell
membrane
Inside
of cell
(cytoplasm)
Protein
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Lipid bilayer
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The Cell Membrane is Fluid
Molecules in cell membranes are constantly
moving and changing
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Cell Membrane Proteins
• Proteins help move large
molecules or aid in cell
recognition
• Peripheral proteins are
attached on the surface
(inner or outer)
• Integral proteins are
embedded completely
through the membrane
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GLYCOPROTEINS
Recognize
“self”
Glycoproteins have carbohydrate tails to act
as markers for cell recognition
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Cell Membrane in Plants
Cell membrane
• Lies immediately
against the cell wall
in plant cells
• Pushes out against
the cell wall to
maintain cell shape
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Cell Wall
Cell wall
• Nonliving layer
• Found in plants, fungi, &
bacteria
• Made of cellulose in
plants
• Made of peptidoglycan
in bacteria
• Made of chitin in Fungi
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Cell Wall
• Supports and protects
cell
• Found outside of the cell
membrane
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Cytoplasm of a Cell
cytoplasm
• Jelly-like substance
enclosed by cell
membrane
• Provides a medium for
chemical reactions to
take place
• Found in ALL Cells
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The Control Organelle - Nucleus
• Controls the normal
activities of the cell
• Contains the DNA in
chromosomes
• Bounded by a
nuclear envelope
(membrane) with pores
• Usually the largest
organelle
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Nuclear Envelope
• Double membrane surrounding
nucleus
• Also called nuclear membrane
• Contains nuclear pores for
materials to enter & leave nucleus
• Connected to the rough ER
Nuclear
pores
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Cytoskeleton
• Helps cell maintain cell shape
• Also help move organelles
around
• Made of proteins
• Microfilaments are
threadlike & made of ACTIN
• Microtubules are tubelike &
made of TUBULIN
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Cytoskeleton
MICROTUBULES
MICROFILAMENTS
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Centrioles
• Found only in animal
cells
• Paired structures near
nucleus
• Made of bundle of
microtubules
• Appear during cell
division forming mitotic
spindle
• Help to pull chromosome
pairs apart to opposite
ends of the cell
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Centrioles & the Mitotic Spindle
Made of MICROTUBULES (Tubulin)
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Mitochondrion
(plural = mitochondria)
• “Powerhouse” of the cell
• Generate cellular energy (ATP)
• More active cells like muscle
cells have MORE mitochondria
• Both plants & animal cells have
mitochondria
• Site of CELLULAR RESPIRATION
(burning glucose)
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MITOCHONDRIA
Surrounded by a DOUBLE
membrane
Has its own DNA
Folded inner membrane
called CRISTAE
(increases surface area
for more chemical
Reactions)
Interior called MATRIX
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Interesting Fact --• Mitochondria Come
from cytoplasm in
the EGG cell during
fertilization
Therefore …
• You inherit your
mitochondria from
your mother!
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What do mitochondria do?
“Power plant” of
the cell
Burns glucose to
release energy (ATP)
Stores energy as ATP
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Endoplasmic Reticulum - ER
• Network of hollow membrane tubules
• Connects to nuclear envelope & cell membrane
• Functions in Synthesis of cell products & Transport
Two kinds of ER
---ROUGH & SMOOTH
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Rough Endoplasmic Reticulum (Rough
ER)
• Has ribosomes on its
surface
• Makes membrane
proteins and proteins
for EXPORT out of cell
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Smooth Endoplasmic Reticulum
• Smooth ER lacks
ribosomes on its surface
• Is attached to the ends
of rough ER
• Makes cell products that
are USED INSIDE the cell
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Functions of the Smooth ER
• Makes membrane
lipids (steroids)
• Regulates calcium
(muscle cells)
• Destroys toxic
substances (Liver)
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Ribosomes
• Made of PROTEINS and rRNA
• “Protein factories” for cell
• Join amino acids to make proteins
• Process called protein synthesis

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Ribosomes
Can be attached to
Rough ER
OR
Be free
(unattached)
in the
cytoplasm
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Golgi Bodies
• Stacks of flattened sacs
• Have a shipping side (trans
face) and receiving side (cis
face)
• Receive proteins made by ER
• Transport vesicles with
modified proteins pinch off
the ends
CIS
TRANS
Transport
vesicle
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Golgi Bodies
Look like a stack of pancakes
Modify, sort, & package
molecules from ER
for storage OR
transport out of cell
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Golgi Animation
Materials are transported from Rough ER
to Golgi to the cell
membrane by VESICLES35
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Lysosomes
• Contain digestive enzymes
• Break down food, bacteria,
and worn out cell parts for
cells
• Programmed for cell death
(AUTOLYSIS)
• Lyse (break open) &
release enzymes to break
down & recycle cell parts)
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Lysosome Digestion
• Cells take in
food by
phagocytosis
• Lysosomes
digest the food
& get rid of
wastes
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Cilia & Flagella
• Made of protein tubes
called microtubules
• Microtubules arranged (9
+ 2 arrangement)
• Function in moving cells, in
moving fluids, or in small
particles across the cell
surface
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Cilia & Flagella
• Cilia are shorter
and more
numerous on
cells
• Flagella are
longer and fewer
(usually 1-3) on
cells
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Cell Movement with Cilia &
Flagella
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Cilia Moving Away Dust Particles from the
Lungs
Respiratory System
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Vacuoles
• Fluid filled sacks
for storage
• Small or absent in
animal cells
• Plant cells have a
large Central
Vacuole
• No vacuoles in
bacterial cells
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Contractile Vacuole
• Found in unicellular
protists like paramecia
• Regulate water intake by
pumping out excess
(homeostasis)
• Keeps the cell from lysing
(bursting)
Contractile vacuole animation
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Chloroplasts
• Found only in producers
(organisms containing
chlorophyll)
• Use energy from
sunlight to make own
food (glucose)
• Energy from sun stored
in the Chemical Bonds
of Sugars
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Chloroplasts
• Surrounded by DOUBLE
membrane
• Outer membrane smooth
• Inner membrane modified into
sacs called Thylakoids
• Thylakoids in stacks called
Grana & interconnected
• Stroma – gel like material
surrounding thylakoids
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Cell Size
Question:
Are the cells in an elephant bigger,
smaller, or about the same size as
those in a mouse?
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Factors Affecting Cell Size
• Surface area (plasma
membrane surface) is
determined by multiplying
length times width (L x W)
• Volume of a cell is
determined by multiplying
length times width times
height (L x W x H)
• Therefore, Volume
increases FASTER than the
surface area
Factors Affecting Cell Size
• DNA Overload
= Not enough
DNA to direct
the whole cell
Factors Affecting Cell Size
• Movement
of
materials
into and
out of the
cell
Cell Size
Question:
Are the cells in an elephant bigger,
smaller, or about the same size as
those in a mouse?
About the same size, but …
The elephant has MANY MORE cells
than a mouse!
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Cell Transport
Plasma Membrane
• Selectively
permeable
barrier
– Allows nutrients
in
– Waste can go
out
Passive Transport
Uses NO Energy
Types of Passive Transport
(No ATP)
• Diffusion:
– Kinetic Energy
– Down or with
Concentration Gradient
– Molecules must be small
or fat soluble to get
across membrane
– Can be either direction
– Heat Increases Speed
• Examples: fats, fat soluble
vitamins, O2, CO2 or small
ions like chloride (Cl-)
DIFFUSION
Diffusion is a PASSIVE
process which
means no energy is
used to make the
molecules move,
they have a natural
KINETIC ENERGY
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Diffusion of Liquids
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Diffusion through a Membrane
Cell membrane
Solute moves DOWN concentration gradient (HIGH to
LOW)
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Types of Passive Transport
• Osmosis
– The diffusion of water
– Polar, but can move through aquaporins made by
proteins in the membrane
– Moves down or with concentration gradient
– Can be either direction
• Example: Only Water
Diffusion of H2O Across A
Membrane
High H2O potential
Low solute concentration
Low H2O potential
High solute concentration
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Types of Passive Transport
• Facilitated Diffusion:
– Large Molecules or Lipid-insoluble
– Down or with the concentration gradient
– Protein channel is needed
– Either direction
• Example: Glucose
Aquaporins
• Water Channels
• Protein pores used during OSMOSISWATER
MOLECULES
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Cell in Isotonic Solution
10% NaCL
90% H2O
ENVIRONMENT
CELL
10% NaCL
90% H2O
NO NET
MOVEMENT
What is the direction of water movement?
equilibrium
The cell is at _______________.
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Cell in Hypotonic Solution
10% NaCL
90% H2O
CELL
20% NaCL
80% H2O
What is the direction of water movement?
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Cell in Hypertonic Solution
15% NaCL
85% H2O
ENVIRONMENT
CELL
5% NaCL
95% H2O
What is the direction of water movement?
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Cells in Solutions
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Cytolysis & Plasmolysis
Cytolysis
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Plasmolysis
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Osmosis in Red Blood Cells
Isotonic
Hypotonic
Hypertonic
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hypotonic
hypertonic
isotonic
hypertonic
isotonic
hypotonic
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Types of Passive Transport
• Filtration:
– Uses pressure gradient (fluid or hydrostatic)
– Filtrate goes from high to low pressure through a
membrane or capillary
• Example: water and solutes filter through kidneys
Active Transport
Requires ATP
Active Transport
(ATP)
• Solute Pump
– ATP energizes protein carriers embedded in
membrane
– Against the concentration or electrical gradient
– Large or not lipid soluble molecules
• Examples: Amino Acids – Large Molecule
Sodium-Potassium Pump - ATP is needed to pump
sodium out of cell where there is more sodium and
potassium that leaks out of the cell has to be pumped
back inside.
Active Transport
uses ATP for Bulk Transport
• Exocytosis:
– Out of the cell
– Transport vesicle (packaged by Golgi)
– Migrates to membrane
– Fuses and then empties outside cell
• Examples: Secreting hormones, mucus, cellular waste
Moving the “Big Stuff”
Exocytosis-
moving
things
out.
Molecules are moved out of the cell by vesicles that fuse with the
plasma membrane.
This is how many hormones are secreted and how nerve cells
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communicate with one another.
Active Transport
uses ATP for Bulk Transport
• Endocytosis
– Into the cell
– Engulfing extra-cellular substances
– Forms a sac around the substance
– Pulls it in and the sac buds off
– Fuses with a lysosome
– Enzymes digest the contents
Types of Endocytosis
• Phagocytosis: Cellular eating. Ex: White
blood cells get rid of bacteria. Protective
• Pinocytosis: Absorption function, droplets are
surrounded and taken in. Ex: dissolved protein
or fat
• Receptor-mediated:Taking up target
molecules, proteins bind only with certain
molecules. Ex: hormones, cholesterol, iron
and sometimes viruses get in this way
Phagocytosis
Used to engulf large particles such as food,
bacteria, etc. into vesicles
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Pinocytosis
Most common form of endocytosis.
Takes in dissolved molecules
as a vesicle.
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Receptor-Mediated Endocytosis
Some integral proteins have receptors on their
surface to recognize & take in hormones,
cholesterol, etc.
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The diagram shows
the cell cycle.
Which of the following
activities occurs in the
G1 phase?
A.
B.
C.
D.
growth of the cell
replication of the
DNA
formation of the
mitotic spindle
breakdown of the
nuclear membrane
The diagram shows
the cell cycle.
Which of the following
activities occurs in the
G1 phase?
A.
B.
C.
D.
growth of the cell
A researcher is studying a particular disease-causing
agent.
The agent has a protein coat, but it lacks a nucleus,
contains no other organelles, and can reproduce only
when it is inside an animal cell. The researcher should
classify the agent as which of the following?
A.
a bacterium
B.
a fungus
C.
a protist
D.
a virus
A researcher is studying a particular disease-causing
agent.
The agent has a protein coat, but it lacks a nucleus,
contains no other organelles, and can reproduce only
when it is inside an animal cell. The researcher should
classify the agent as which of the following?
A.
B.
C.
D.
a virus
A lab technician needs to determine whether cells in a test tube
are prokaryotic or eukaryotic.
The technician has several dyes she could use to stain the cells.
Four of the dyes are described in the table below.
Which dye could the technician use to determine whether the cells
are prokaryotic or eukaryotic?
Dye
Test
acridine orange
stains DNA and RNA
osmium tetroxide
stains lipids
eosin
stains cell cytoplasm
Nile blue
stains cell nuclei
A.
acridine orange
B.
osmium tetroxide
C.
eosin
D.
Nile blue
A lab technician needs to determine whether cells in a test tube
are prokaryotic or eukaryotic.
The technician has several dyes she could use to stain the cells.
Four of the dyes are described in the table below.
Which dye could the technician use to determine whether the cells
are prokaryotic or eukaryotic?
Dye
Test
acridine orange
stains DNA and RNA
osmium tetroxide
stains lipids
eosin
stains cell cytoplasm
Nile blue
stains cell nuclei
A.
B.
C.
D.
Nile blue
If a cell’s lysosomes were damaged,
which of the following would most likely occur?
A.
The cell would produce more proteins
than it needs.
B.
The cell would have chloroplasts that
appear yellow rather than green.
C.
The cell would be less able to break
down molecules in its cytoplasm.
D.
The cell would be less able to regulate
the amount of fluid in its cytoplasm.
If a cell’s lysosomes were damaged,
which of the following would most likely occur?
A.
The cell would produce more proteins
than it needs.
B.
The cell would have chloroplasts that
appear yellow rather than green.
C.
The cell would be less able to break
down molecules in its cytoplasm.
D.
The cell would be less able to regulate
the amount of fluid in its cytoplasm.
If an animal cell is placed in distilled water,
it will swell and burst.
The bursting of the cell is a result of
which biological process?
A.
active transport
B.
enzyme activity
C.
osmosis
D.
respiration
If an animal cell is placed in distilled water,
it will swell and burst.
The bursting of the cell is a result of
which biological process?
A.
active transport
B.
enzyme activity
C.
osmosis
D.
respiration
Scientists believe that the first organisms that appeared
on Earth were prokaryotic. Which of the following best
represents what the cell structure of these organisms
may have looked like?
Scientists believe that the first organisms that appeared
on Earth were prokaryotic. Which of the following best
represents what the cell structure of these organisms
may have looked like? No Nucleus
The illustrations below represent two different cells.
Which of the following
statements best
Identifies these two cells?
A.
Cell X is a prokaryotic cell and cell Y is a eukaryotic cell.
B.
Cell X is an archae cell and cell Y is a eubacterial cell.
C.
Cell X is a red blood cell and cell Y is a muscle cell.
D.
Cell X is a plant cell and cell Y is an animal cell.
The illustrations below represent two different cells.
Which of the following
statements best
Identifies these two cells?
A.
Cell X is a prokaryotic cell and cell Y is a eukaryotic cell.
B.
Cell X is an archae cell and cell Y is a eubacterial cell.
C.
Cell X is a red blood cell and cell Y is a muscle cell.
D.
Cell X is a plant cell and cell Y is an animal cell.
The diagram below shows a cross section of part of
a cell membrane.
a. Describe the basic structure of the cell membrane.
b. Describe two primary functions of the cell membrane.
c. Explain how the structure of the cell membrane allows it
to perform the functions described in part (b).
A. Describe the basic structure of the cell
membrane.
• A.) The cell membrane is made up of 2 layers
of phospholipids. The hydrophyllic heads
point outward, while the hydrophobic tails
point inward. This is because the cytoplasm
inside the cell and the fluid outside the cell
contain water. Proteins can also be found in
the membrane and their function is to
facilitate diffusion, to act a s a pump, or as
identifying markers.
B. Describe two primary functions of the cell
membrane.
• B) The primary functions of the cell
membrane are, first, to maintain a boundary
that keeps the organelles and cytoplasm
inside and the other particles outside.
Second, the membrane is selectively
permeable allowing nutrients in and waste
products out as well as protecting the cell.
C. Explain how the structure of the cell
membrane allows it to perform the
functions described in part (B).
• C.) The structure of the cell membrane allows
it to perform its functions. The lipid bilayer
forms a strong flexible barrier between the
cell and its surroundings which repels water
and large molecules. The protein molecules
embedded in the bilayer act as channels or
pumps to allow certain molecules in or out of
the cell. In addition, some of the proteins
have carbohydrate chains attached that act as
identification markers.
Which of the following functions does active
transport perform in a cell?
A. packaging proteins for export from
the cell
B. distributing enzymes throughout the
cytoplasm
C. moving substances against a
concentration gradient
D. equalizing the concentration of water
inside and outside the cell
Which of the following functions does active
transport perform in a cell?
A. packaging proteins for export from
the cell
B. distributing enzymes throughout the
cytoplasm
C. moving substances against a
concentration gradient
D. equalizing the concentration of water
inside and outside the cell
Which of the following is a main
function of the cell wall?
A.
B.
C.
D.
to store carbohydrates for later use
to give the cell a rigid structure
to package proteins for export
to carry out photosynthesis
Which of the following is a main
function of the cell wall?
A.
B.
C.
D.
to store carbohydrates for later use
to give the cell a rigid structure
to package proteins for export
to carry out photosynthesis
Which of the following statements
correctly matches a cell part with
its function?
A. The cell membrane packages lipids
for export
B. The mitochondria perform
photosynthesis.
C. The lysosome digests molecules.
D. The nucleus produces energy.
Which of the following statements
correctly matches a cell part with
its function?
A. The cell membrane packages lipids
for export
B. The mitochondria perform
photosynthesis.
C. The lysosome digests molecules.
D. The nucleus produces energy.
The drawing below represents an organism that a
student observed when examining a sample of pond
water with a light microscope.
• The student identified
this organism as a
prokaryote.
• A.) Is the student's
identification accurate?
Explain your answer
using information from
the diagram.
• B.) Identify three
similarities between the
cells of prokaryotes and
eukaryotes.
A.) Is the student's identification accurate? Explain your
answer using information from the diagram.
• No, the student is not correct. This
organism has a nucleus and membrane
bound organelles, a prokaryote does not
have these things.
B.) Identify three similarities between the cells of
prokaryotes and eukaryotes.
• Three similarities between prokaryotes and
eukaryotes are: 1.) Both have DNA which
contains its genetic information. 2.) Both
grow and reproduce and 3.) Both have a cell
membrane
Some cells, such as human nerve and muscle cells,
contain many more mitochondria than do other cells,
such as skin cells. Why do some cells have more
mitochondria than others?
A. The cells use more energy.
B. The cells store more nutrients.
C. The cells degrade more proteins.
D. The cells divide more frequently.
Some cells, such as human nerve and muscle cells,
contain many more mitochondria than do other cells,
such as skin cells. Why do some cells have more
mitochondria than others?
A. The cells use more energy.
B. The cells store more nutrients.
C. The cells degrade more proteins.
D. The cells divide more frequently.
A single prokaryotic cell can divide several times in an
hour. Few eukaryotic cells can divide as quickly. Which
of the following statements best explains this
difference?
A.Eukaryotic cells are smaller than prokaryotic
cells.
B.Eukaryotic cells have less DNA than
prokaryotic cells.
C.Eukaryotic cells have more cell walls than
prokaryotic cells.
D.Eukaryotic cells are more structurally complex
than prokaryotic cells.
A single prokaryotic cell can divide several times in an
hour. Few eukaryotic cells can divide as quickly. Which
of the following statements best explains this
difference?
A.Eukaryotic cells are smaller than prokaryotic
cells.
B.Eukaryotic cells have less DNA than
prokaryotic cells.
C.Eukaryotic cells have more cell walls than
prokaryotic cells.
D.Eukaryotic cells are more structurally complex
than prokaryotic cells.
The diagram below illustrates how plant root cells
take in mineral ions from the surrounding soil.
• Which of the following
processes is illustrated?
A. Active transport
B. Diffusion
C. Osmosis
D. Passive filtration
The diagram below illustrates how plant root cells
take in mineral ions from the surrounding soil.
• Which of the following
processes is illustrated?
A. Active transport
B. Diffusion
C. Osmosis
D. Passive filtration
Which of the diagrams below best represents the net
movement of molecules in osmosis?
• A.
• C.
• B.
• D.
Which of the diagrams below best represents the net
movement of molecules in osmosis?
• A.
• C.
• B.
• D.
A cross section of part of a Golgi
complex is shown below.
Part of the membrane of the
Golgi complex pinches off and
moves away. Which of the
following is a function of this
process?
• A. to release energy
from ATP
• B. to deliver proteins to
other locations in the cell
• C. to collect amino acids
for use in protein
synthesis
• D. to send messages
about cell requirements
to the nucleus
A cross section of part of a Golgi
complex is shown below.
Part of the membrane of the
Golgi complex pinches off and
moves away. Which of the
following is a function of this
process?
• A. to release energy
from ATP
• B. to deliver proteins to
other locations in the cell
• C. to collect amino acids
for use in protein
synthesis
• D. to send messages
about cell requirements
to the nucleus