Cell Biology:
Cell Structure and Function
Lesson 1 – Eukaryotic Cells and Organelles (Inquiry into Life pg. 49-62)
Today’s Objectives
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Analyze the functional inter-relationships of cell
structures, including:
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Describe the major cell structures and their functions
State the balanced chemical equation for cellular respiration
Describe how the Endomembrane System functions to
compartmentalize the cell and move materials through it
Identify cell structures depicted in diagrams and electron
micrographs
The Cell
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The cell is the
structural and
functional unit of an
organism.
It is the smallest
structure capable of
performing all the
functions necessary
for life.
The study of cells
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The study of cells had its birth with the invention of the
microscope, but it became a product of the 19th
century. As biologists became increasingly familiar with
the detailed microscopic features of organism they were
able to make certain generalizations about cells.
In the late 1830’s two German biologists,
Schleiden ( a botanist) and Schwann, (a
zoologists) made similar claims.
They realized that all organisms they were
studying were composed of cells. Their
discoveries are now
generalized as
“ The cell is the
building block of all
organisms.”
A few years later,
Rudolph Virchow
added the observation
that cells “come from
pre-existing cells.”
These two statements
comprise what is now
known as the Cell
Theory.
Cell Theory
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Cell theory states:
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All organisms are composed of one or more cells.
Cells are the basic unit of structure and function in
an organism.
All cells come from other cells.
Cell Size
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Cells are very small. Most cells are between 1
micrometer (1 thousandth of a millimeter) and 100
micrometers.
Cell Size
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Small cells are advantageous to multicellular organisms.
Nutrients and wastes are passed through the cell at its surface,
therefore the amount of surface area affects the ability to
material in and out of the cell.
As cells increase in volume, the proportionate amount of
surface area decreases.
Surface Area: 96 cm2
192 cm2
384 cm2
Types of Cells
 There are two overall classifications of cells:
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Prokaryotic cells (simple cells)
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Do not contain nucleus or membrane enclosed organelles
Found in Bacteria, Archaea
Usually exist as single celled organisms (unicellular)
Eukaryotic cells (complex cells)
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possess nucleus and organelles
Contains internal membranes
Multicellular organisms
Prokaryotic Cells
Eukaryotic Cells
Examples of Eukaryotic cells include Plants,
Animals, Protists, Fungi.
Prokaryotic cells are considered to be less efficient than Eukaryotic
cells because the chemical reactions occur all over the cytoplasm
rather than in areas of specialization.
Cell Organelles – Plant Cell
Cell Organelles – Animal Cell
Nucleus
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Largest Organelle.
Surrounded by a
double-layered membrane
(the nuclear envelope).
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Membrane has pores through which larger molecules
pass. (Nuclear Pores)
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Control center for the cell’s functions. (The brain).
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Contains a fluid called the nucleoplasm.
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Contains chromatin (DNA strands which forms
chromosomes during cell division.)
Nucleus and Nuclear Envelope
Nucleolus
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Dark region in the Nucleoplasm.
One or more found in the nucleus.
Site where ribosomal RNA
(rRNA) is produced or
stored.
Involved in interactions between
the nucleus and the cytoplasm.
Chromatin
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The hereditary material of the cell.
Condenses to form chromosomes during cell
division.
Composed of Protein and DNA
Chromosomes
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Condensed chromatin
Contains the hereditary
information. (genes)
Rod-shaped bodies in the
nucleus, particularly during cell
division
Each eukaryotic species has a characteristic
number of chromosomes
A typical human
cell has 46
chromosomes, but
sex cells (eggs
and sperm) have
only 23
chromosomes.
Cytoplasm
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A semifluid (like a gel) medium composed of water, salts
and dissolved organic molecules
Contains and supports all the cells organelles.
Plasma Membrane
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All cells are surrounded
by a plasma membrane.
The material inside of a
cell is the cytoplasm.
The plasma membrane
regulates what enters
and exits a cell.
Plasma Membrane (cell membrane)
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Composed of proteins and phospholipids (fats with
Phosphorus).
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Acts as skin around the cells contents.
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Acts as a selectively permeable membrane to allow
movement of materials in and out of the cell.
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Located around the outside of the cell.
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Single membrane around the vacuoles, lysosomes, E.R., Golgi
Apparatus.
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Double membrane around the nucleus and mitochondria
The Endomembrane System
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Consists of:
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Nuclear Envelope
Endoplasmic reticulum
Golgi apparatus
Vesicles
This system compartmentalizes the cell so that particular
enzymatic reactions are restricted to specific regions
Organelles of the endomembrane system are connected
directly or by transport vesicles
Smooth Endoplasmic Reticulum (Smooth ER)
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System of interconnected
flattened tubes, sacs, or
canals.
Begins at the nuclear
envelope and branches
throughout the
cytoplasm to the cell
membrane.
Moves molecules from
one area to another.
-Location of lipid manufacture. Cells that
produce steroid hormones, have an
abundant smooth ER.
-Section of both types of ER can break free
“blebbing” to produce small membrane
bound sacs of either
proteins or lipids called
vesicles.
-Contains enzymes that
synthesize lipids and
related products such as
steroids.
Rough Endoplasmic Reticulum (Rough ER)
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Like Smooth E.R., but
with attached
ribosomes.
Folds and processes
proteins and packages
them in transport
vesicles
Abundant in cells that
produce large amounts of
protein for export from
the cell.
Golgi Apparatus (Golgi Body)
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Stack, of a half dozen or more flattened sacs.
On one side receives protein-filled vesicles from the
E.R.
Sorts the proteins and packages them in vesicles at the
other side. From here the vesicles move to different
locations in the cell.
Like the post office of the cell.
• Many transport vesicles from the ER travel to the
Golgi apparatus for modification of their contents.
• The Golgi is a center of manufacturing,
warehousing, sorting, and shipping.
• The Golgi apparatus is especially extensive in cells
specialized for secretion.
Vesicles and Vacuoles
Vesicles and vacuoles (larger versions) are membrane bound sacs with
varied functions.
Vacuoles
 Storage areas for water, nutrients, and salts.
Vesicles
 A small vacuole
 Storage sites in various kinds of molecules.
 Transport and secretory vesicles move their contents within the cell
and in and out of the cell.
 Can be made by the Golgi Apparatus or from an infolding of the cell
membrane
Lysosomes
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Special vacuoles formed by the golgi body. (double
membrane)
Contain powerful digestive enzymes that break
down unwanted, foreign substances or worn-out
parts of cells
The Endomembrane System
Fig. 7.14
Ribosomes
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Contain rRNA and protein subunits.
Function as sites for protein synthesis.
Found on ER (proteins for export) or in the cytoplasm
(proteins for use in the cell).
- Several ribosomes together in a line, all producing the same
protein is called a polyribosome.
Mitochondria (singular – Mitochondrion)
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Burn glucose to produce adenosine triphosphate
(ATP).
Use up oxygen and give off carbon dioxide (this process
is called cellular respiration).
C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy
Composed of two membranes.
-Considered the powerhouse of the cell.
-Their inner membranes loop back and fourth through
the inner fluid, matrix, of the mitochondria
increasing its surface area and producing shelf-like
structures called cristae.
-This inner
membrane is the
site of cellular
respiration
Cytoskeleton
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Protein components of
cytoskeleton provide internal
structure to maintain the cell’s
shape, anchor the organelles, and
allows them to move when
appropriate.
Composed of microfilaments
(actin filaments)
and microtubules.
Like the “bones and muscles” of the
cell
Cytoskeleton – Microfilaments (Actin Filaments)
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Primarily functions to maintain cell structure and
cell movements
Extremely thin protein fibers usually occurring in bundles.
Similar in composition to the protein in the muscle
(allows for muscle contraction).
Cytoskeleton - Microtubules
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Maintain the shape of the cell and act as tracks that
organelles can move on.
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Thin cylinders several times larger than microfilaments.
Found in both cytoplasm and certain organelles.
Used to construct material to make up Cilia, Flagella and
Centrioles.
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Other Organelles
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Centrioles:
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short cylinders with a 9+0 pattern of
microtubule triplets
Two centrioles lying at right angles form the
centrosome which is the microtubule
organizing center (MTOC)
Cilia and Flagella:
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Hair like projections that can move in
undulating fashion (like a whip) or stiffly (like
an oar)
Cells with cilia and/or flagella are capable of
movement
Cilia also line the respiratory system and
help remove foreign material from the lungs
A cell is a living unit greater than the sum
of its parts
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While the cell has many structures that have specific
functions, they must work together.
The enzymes of the lysosomes and proteins of the
cytoskeleton are synthesized at the ribosomes.
The information for these proteins comes from genetic
messages sent by DNA in the nucleus.
All of these processes require energy in the form of ATP,
most of which is supplied by the mitochondria.
A cell is a living unit greater than the sum of its parts.
ABCD Quiz!
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I believe you all know how to play this game:
Groups of 4
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1 scorekeeper
4 contestants
I will show a clue about an organelle, each team member
will guess one of the 4 choices provided
Team with highest score wins
No notes or books allowed
Question 1
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I am the largest organelle in a cell, and I contain
hereditary material. I am a:
A) Ribosome
B) Mitochondrion
C) Nucleus
D) Golgi Apparatus
Answer is C
Question 2
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I am composed of phospholipids and proteins and I
control what enters and exits the cell. I am a:
A) Plasma Membrane
B) Lysosome
C) Vesicle
D) Smooth ER
Answer is A
Question 3
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I am kind of like the subway system of the cell because I
transport molecules from one place to another. I am a:
A) Rough ER
B) Vesicle
C) Lysosome
D) Mitochondrion
Answer is B
Question 4
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I receive protein filled transport vesicles from the ER
which I then sort and repackage for use inside the cell. I
am the:
A) Ribosome
B) Vacuole
C) Cytoplasm
D) Golgi Apparatus
Answer is D
Question 5
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I synthesize protein and I can be found in the cytoplasm
or attached to another organelle. I can also be found in
groups. I am a:
A) Mitochondrion
B) Ribosome
C) Lysosome
D) Microfilament
Answer is B
Question 6
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I have attached ribosomes that synthesize proteins which
I then process and package. Cells that export a lot of
protein have a lot of me! I am the:
A) Lysosome
B) Nuclear Envelope
C) Rough ER
D) Smooth ER
Answer is C
Question 7
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I have a double membrane and I am the site of cellular
respiration and production of ATP. I am a:
A) Mitochondrion
B) Golgi Apparatus
C) Smooth ER
D) Rough ER
Answer is A
Question 8
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My job is to digest nutrients for use in the cell or to get
rid of unwanted molecules and waste. I am a:
A) Vesicle
B) Nucleus
C) Lysosome
D) Ribosome
Answer is C
Question 9
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I maintain the shape of the cell and allow different
organelles to move around the cytoplasm. I am the:
A) Cytoplasm
B) Vesicle
C) Cytoskeleton
D) Plasma Membrane
Answer is C
Question 10
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I am capable of forming transport vesicles and lipids and
steroids are synthesized inside of me. I am:
A) Rough ER
B) Smooth ER
C) Golgi Apparatus
D) Mitochondrion
Answer is B