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Chapter 4:
Structure and Function
of the Cell
Essential Question: How do the cell
structures vary with their functions?
I. Introduction to the cell
A. Discovery of cells was made possible by the
development of the microscope
1. Robert Hooke in 1665 was the
first to call the “little boxes” he saw in
cork cells (dead plant cells)
2. Anton van Leeuwenhoek in 1673 was the
first to observe living cells
B. Cell theory
1. All living things are composed of one or more
cells
2. Cells are the basic units of structure and function
in an organism
3. Cells come only from the reproduction of
existing cells
4. Three German scientists showed evidence to
support the theory
a) Matthias Schleiden: plant cells
b) Theodor Schwann: animal cells
c) Rudolf Virchow: cells come from cells
Timeline Cell Theory
II. Introduction to Cells
A. Size: Some cells are visible to see with your eyes,
but most are only visible with a microscope
1. Most plant and animal cells are 10-50m (.002
in) in diameter and some bacteria cells are 0.2m
(0.000008 in)
2. Cells are limited in size by the ratio between
their outer surface area and their volume
3. If the cell grows larger, at some point its
surface area becomes too small to allow nutrients
to quickly enter the cell Demo
B. Shape: cells come in a variety of shapes
and the shape reflects what function it
performs
1. nerve cells: long extensions
2. skin cells: flat for covering the body
3. white blood cells can change shape
C. Basic Parts of a Cell
1. Plasma membrane: (cell membrane): outer
boundary that covers a cell’s surface and acts as a
barrier
2. Cytoplasm: region inside the plasma membrane
that includes the fluid, cytoskeleton, and all
organelles
a) cytosol: part of cytoplasm that contains
molecules and small particles
3. Nucleus: membrane bound organelle that
contains the cell’s genetic information and controls
the cell
parts of cell
D. Two types of cells
1. Eukaryotes: organisms whose cells contain a
membrane- bound nucleus and other organelles
a) organelles: intracellular bodies that perform
specific functions for the cell (little organs)
b) plants, animals, fungi and protists
c) multicellular and unicellular
d) larger and complex
2. Prokaryotes: unicellular organisms that lack
a membrane -bound nucleus and other
organelles
a) simple
b) bacteria
Prokaryotes and eukaryotes
Prokaryotic and Eukaryotic Cells
Section 7-1
Cell membrane
Cytoplasm
Prokaryotic Cell
Cell membrane
Cytoplasm
Nucleus
Eukaryotic Cell
Organelles
Go to
Section:
E. Cellular organization
1. Colonies: collection of genetically identical cells
that live together in a connected group
2. Multicellular organisms: cells are specialized
and can not survive on their own
a) tissue: group of similar cells
b) organ: group of tissues that perform a certain
function
c) organ system: group of organs that
accomplish related tasks
Section 7- 4
Go to
Section:
Review of Prokaryotes and Eukaryotes
Comparison Prezi
III. Cell Organelles and Features
A. Plasma or Cell membrane: thin membrane that
controls which substance pass into and out of the
cell
1. Selectively permeable: allows some
substances to cross membrane and other
substances cannot cross Selectively
2. Membrane lipids
a) Phospholipid: polar head (hydrophilic) and 2
nonpolar tails (hydrophobic)
b) Creates two layers called the phospholipid
bilayer
c) Polar heads are toward the outside of the cell
d) Nonpolar tails are toward the interior
e) sterols: lipids that fit between the tails and
make the membrane more firm Example:
cholesterol
The Structure of the Cell
Membrane
Section 7-3
Outside
of cell
Proteins
Carbohydrate
chains
Cell
membrane
Inside
of cell
(cytoplasm)
Go to
Section:
Protein
channel
Lipid bilayer
3. Membrane proteins
a) peripheral proteins: attach to the surface of
cell membrane on interior and exterior surface
b) integral proteins: embedded in the bilayer
and may have a carbohydrate attached that
extends to the outside of the cell
i) act as channels or pores to move
substance across membrane or to bind to
substance to carry them across
Proteins
The Structure of the Cell
Membrane
Section 7-3
Outside
of cell
Proteins
Carbohydrate
chains
Cell
membrane
Inside
of cell
(cytoplasm)
Go to
Section:
Protein
channel
Lipid bilayer
4. Fluid mosaic model: cell membrane
behaves more like a fluid than a solid
a) proteins can move within the lipid
bilayer
b) lipids and proteins in the membrane are
constantly changing
Fluid mosaic
B. Nucleus
1. Large organelle near the center of the cell
2. Function: cell’s genetic information and
controls activities of the cell
3. Nucleoplasm: jellylike liquid which holds the
contents of the nucleus
4. Nuclear envelope (membrane): double
membrane around the nucleus
5. Chromatin: fine strands made of DNA and
protein
6. Chromosomes: densely packed chromatin
during division
7. Nuclear pores: small holes in the nuclear
envelope that allows RNA to pass
8. Nucleolus: site where ribosomes are made
and partially assembled
Nucleus
C. Mitochondria: makes energy (powerhouse of cell)
1. Function: site of chemical reactions that
transfer energy from ATP
2. Inner and outer membranes
a) Cristae: folds in the inner membrane which
increases the surface area so more reactions can
take place
3. Mitochondria have their own DNA
D. Ribosomes: small, spherical organelle
1. Function: role in making proteins
2. Made of protein and RNA
3. Some ribosomes are free in the cytosol and
make proteins used by the cytosol
4. Some ribosomes attach to the endoplasmic
reticulum and make proteins for membrane or
exported from the cell
E. Endoplasmic reticulum: ER
1. System of membranous tubules and sacs
2. Function: intracellular highway that moves
molecules from one part of the cell to another
3. Rough ER: contains ribosomes
4. Smooth ER: no ribosomes, performs other
functions depending on type of cell
ER
F. Golgi apparatus
1. Function: processing, packaging, and
secreting proteins
2. System of membranes or series of flattened
sacs
3. Modifies proteins for export by the cell
Golgi
G. Vesicles: small, spherical sacs that perform various
functions
1.Lysosomes: small and spherical with digestive
enzymes produced by Golgi
a) Function: uses enzymes to digest proteins,
carbohydrates, lipids, DNA, RNA, old organelles,
bacteria
2. Peroxisomes: contain enzymes that breakdown
alcohol, drugs, and fatty acids and they produce
hydrogen peroxide
• http://www.cellsalive.com/cells/cell_model.ht
m
H. Cytoskeleton: network of long protein strands
1. Function: structure of the cell to maintain its
shape and size and participates in the movement
of organelles within the cytosol
2. Microfilaments: small threads made of a
protein called actin and are used for cell
movement and contraction of muscle cells
3. Microtubules: large strands of hollow tubes
that group together during cell division, hold
organelles in place, maintain cell shape, and act
as tracks that guide organelles
Cytoskeleton
Section 7-2
Cell membrane
Endoplasmic
reticulum
Microtubule
Microfilament
Ribosomes
Go to
Section:
Michondrion
4. Cilia and Flagella
a) hairlike organelles that extend from the surface
of the cell
b) assist in movement
c) cilia: short and occur in large numbers
d) flagella: long and less numerous
Cilia and Flagella
5. Centrioles: two short cylinders of
microtubules located near nuclear envelope
a) occur in animal cells only
b) organize microtubules during cell division
• http://biologica.concord.org/webtest1/Shout3d
_cell_6_1_00/v2_frameset.htm
IV. Unique Features of Plant Cells
A. Plant Cells: need three additional structures
because they go through photosynthesis
B. Cell wall: rigid covering outside the cell
membrane with pores
1. Supports and protects the plant
2. Made of cellulose
3. Primary cell wall: when plant cell is forming
4. Secondary cell wall: when cell reaches its full size,
a woody tough wall develops
Cell Wall
C. Central vacuoles: fluid-filled organelles that store
enzymes and wastes
1. Large and can take up most of the cell
2. Separates toxic substance from the rest of the
cell
http://www.cellsalive.com/cells/cell_model.htm
Vacoule
D. Plastids: two membranes and contains DNA
1. Chloroplast: type of plastid where photosynthesis
occurs
a) thylakoids: flattened membranous sacs in the
chloroplast
b) chlorophyll: green pigment that absorbs light
2. Chromoplasts: contain colorful pigments that may or
may not take part in photosyntheis
( orange pigment in carrots)
Chloroplast
E. Comparing Cells
1. All cells share common features (cell membrane,
cytoplasm, ribosomes, and genetic information)
2. Prokaryotes vs. Eukaryotes
a) Prokaryotes: lacks nucleus and organelles
b) Eukaryotes: nucleus and organelles
3. Plant cells vs. Animal cells
a) Plants: 3 different features
important for plant function are
cell wall, central vacuole, plastids
b) Animal: do not need
these extra features