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Chapter 03
*Lecture Outline
*See separate Image PowerPoint slides for all
figures and tables pre-inserted into
PowerPoint without notes.
2
3.1: Introduction
• The basic organizational structure of the human body is the
cell.
• There are about 75 trillion cells in the human body.
• Cell size is measured in micrometers.
• Differentiation is when cells specialize.
• As a result of differentiation, cells vary in size and shape
due to their unique function.
3
3.2: A Composite Cell
• Also called a ‘typical’
cell
• Major parts include:
• Nucleus
• Cytoplasm
• Cell membrane
Microtubules
Flagellum
Nuclear envelope
Basal body
Chromatin Ribosomes
Cell membrane
Mitochondrion
Cilia
Microtubules
Microtubule
Centrioles
Microvilli
L ysosomes
Nucleolus
Nucleus
Phospholipid bilayer
Smooth
Endoplasmic
reticulum
Rough
Endoplasmic
reticulum
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Golgi apparatus
Secretory
vesicles
The nucleus is usually innermost and is enclosed by the
nuclear envelope. It contains DNA which directs the
cells functions.
The cytoplasm includes the organells that provide specific
functions such as extracting energy from nutrients,
dismantling debris, or packaging secretions.
The cell membrane(also called a plasma membrane),
mainly composed of lipids and proteins, contains the
cytoplasm which surrounds the nucleus.
It is self sealing but if extensively damaged the cell dies.
4
5
Cell Membrane
(aka Plasma Membrane) • Outer limit of the cell
• Controls what moves in and out of the cell
• Selectively permeable—it decides what goes through or not
• Phospholipid bilayer • Water-soluble “heads” form surfaces (hydrophilic)
• Water-insoluble “tails” form interior (hydrophobic)
• Permeable to lipid-soluble substances--
• Cholesterol stabilizes the membrane
• Proteins: • Receptors
• Pores, channels and carriers
• Enzymes
• CAMS
• Self-markers
6
Cell Membrane
Cell membrane
Cell membrane (b) (a)
“Heads” of
phospholipid
“Tails” of
phospholipid
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a: © Biophoto Associates/Photo Researchers, Inc.
Fibrous protein Carbohydrate Glycolipid
Glycoprotein
Extracellular side
of membrane
Cytoplasmic side
of membrane
Cholesterol
molecules Globular
protein
Double
layer of
Phospholipid
molecules
Hydrophobic
fatty acid
“tail”
Hydrophilic
Phosphate
“head”
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Table 3.1
Fig. 3.7
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Double
layer of
phospholipid
molecules
Fibrous protein
Extracellular side
of membrane
Glycolipid Carbohydrate
Glycoprotein
Hydrophobic
fatty acid
“tail”
Hydrophilic
phosphate
“head”
Globular
protein
Cytoplasmic side
of membrane
Cholesterol
molecules
9
3.1 Clinical Application
Faulty ion channels cause disease
Page 90 in your book describes how
pain intensity, irregular heartbeats,
and cystic fibrosis have something in
common.
Page 84
11
Cell Adhesion Molecules
(CAMs)
• Guide cells on the move
•Helps cells get where they need to
• Integrin – guides white blood
cells through capillary walls
• Important for growth of
embryonic tissue
• Important for growth of nerve
cells
Adhesion
White blood cell
Integrin
Selectin
Exit
Splinter
Attachment
(rolling)
Blood vessel
lining cell
Carbohydrates
on capillary wall
Adhesion
receptor proteins
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White blood cell
Attachment
(rolling)
Adhesion
Integrin
Blood vessel
lining cell Exit
Splinter
Adhesion
receptor proteins
Carbohydrates
on capillary wall
Selectin
13
Cytoplasm
• Cytoplasm = networks of membranes and organelles
suspended in the cytosol
•Activities of the cells occur mainly in the cytoplasm
•Cytoskeleton= forms supportive framework and is
made of protein rods and tubules
•The following slide are cytoplasmic organelles and their
functions
14
Organelles
Endoplasmic Reticulum (ER)
• Connected, membrane-bound
sacs, canals, and vesicles
• Transport system
• Rough ER • Studded with ribosomes
• Smooth ER • Lipid synthesis
• Added to proteins
arriving from rough ER
• Break down of drugs Ribosomes
• Free floating or connected to ER
• Provide structural support and enzyme activity
to amino acids to form protein
Membranes
Ribosomes
Membranes
(b) (c)
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ER membrane
Ribosomes
(a)
(a): © Don W. Fawcett/Photo Researchers, Inc.
Golgi apparatus
• Stack of flattened,
membranous sacs
• Modifies, packages
and delivers proteins
Vesicles
• Membranous sacs
• Store substances
15
Organelles Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Nuclear
envelope
Nucleus
Cytosol
Rough
endoplasmic
reticulum
Golgi
apparatus
Secretion
Transport
vesicle
Cell membrane (a) (b)
a: © Gordon Leedale/Biophoto Associates
16
Organelles
Inner membrane
Outer membrane
Cristae
(a) (b)
a: © Bill Longcore/Photo Researchers, Inc.
Mitochondria
• Membranous
sacs which
captures and
transfers energy
into ATP
• Generate energy
The Mitochondria uses cellular
respiration . It is a chemical reaction that
releases energy from glucose and other
nutrients. It captures and transfers this
newly released energy into special
chemical bonds of the molecule
adenosine triphosphate( ATP)
17
Fig. 3.11
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1
2
3
4
5
6
7
Lysosome Lipids are
synthesized
in the smooth
endoplasmic
reticulum (ER).
Mitochondrion
Cell membrane
Carbohydrates
Nuclear pore
Nuclear envelope
Milk protein genes are
transcribed into mRNA.
mRNA exits through
nuclear pores.
Most proteins are synthesized
on ribosomes associated with
membranes of the rough ER,
using amino acids in the cytosol.
Sugars are synthesized in the
smooth ER and Golgi apparatus
and may be attached to proteins
or secreted in vesicles.
Proteins are secreted from
vesicles that bud off of the
Golgi apparatus.
Fat droplets pick up a layer of
lipid from the cell membrane
as they exit the cell.
Milk
protein mRNA
Milk
protein
in Golgi
vesicle
19
Organelles
Lysosomes
• Enzyme-containing
sacs
• Digest worn out cell
parts or unwanted
substances
Peroxisomes
• Enzyme-containing
sacs
• Break down organic
molecules
Centrosome
• Two rod-like centrioles
• Used to produce cilia and
flagella
• Distributes chromosomes
during cell division
(a) (b)
)
a
20
Organelles
Cilia---motile extensions—fringe the
free surfaces of some epithelial
cells—propels mucus over the lining
of the respiratory tract
• Short hair-like projections
• Propel substances on cell
surface
Flagellum
• Long tail-like projection
• Provides motility to sperm
(a)
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a: © Oliver Meckes/Photo Researchers, Inc.
© Colin Anderson/Brand X/CORBIS
21
Microfilaments and microtubules
• Thin rods and tubules
• Support cytoplasm
• Allows for movement of
organelles
Organelles Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Nucleus Mitochondrion Vesicle
Rough
endoplasmic
reticulum
Cell membrane
(a) Microfilaments Microtubules Ribosome
(b) b: © K.G. Murti/Visuals Unlimited
22
3.2 Clinical Application
Disease at the Organelle Level p. 95
If mitochondria cannot synthesize proteins required
to carry out energy reactions.
Krabbe disease is a lsysosomal storage disease. It
results when one of the organelle’s enzymes is not
present within a certain concentration range.
ALD decrease in enzyme normally manufactured in
peroxisomes. The enzyme controls breakdown of a
type of fatty acid. Death comes in a few years.
1992 film Lorenzo’s oils told the story.
23
Cell Nucleus
•Control center of the cell
• Nuclear envelope
• Porous double membrane
• Separates nucleoplasm from
cytoplasm
• Nucleolus
• Dense collection of RNA and
proteins
• Site of ribosome production
• Chromatin
• Consists of all the cell’s 46
chromosomes, each containing DNA
wound around proteins
• Fibers of DNA and proteins
• Stores information for synthesis of
proteins
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Nucleus
Nucleolus
Chromatin
(a)
Nuclear
pores
Nuclear
envelope
24
3.3: Movements Into
and Out of the Cell
Physical (Passive) Processes
• Require no cellular
energy and include:
• Simple diffusion
• Facilitated diffusion
• Osmosis
• Filtration
Physiological (Active) Processes
• Require cellular energy and
include:
• Active transport
• Endocytosis
• Exocytosis
• Transcytosis
25
Simple Diffusion
• Movement of substances from regions of higher concentration to
regions of lower concentration---the concentration gradient
• Oxygen, carbon dioxide and lipid-soluble substances
T ime
Solute molecule
W ater molecule
A B A B
(2) (3)
Permeable
membrane
A B
(1)
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26
Facilitated Diffusion
• Diffusion across a membrane with the help of a channel or carrier
molecule
• Glucose and amino acids
•Think “revolving door”
But only down a concen-
tration gradient and is
specific for a particular
Solute– if the concentration
Inside is too high it will not
transfer
Region of higher
concentration
Transported
substance
Region of lower
concentration Protein carrier
molecule
Cell
membrane
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27
Osmosis
• Movement of water through a selectively permeable
membrane from regions of higher concentration to
regions of lower concentration
• Water moves toward a higher concentration of solutes
T ime
Protein molecule
W ater molecule
A
B
A B
(1) (2)
Selectively
permeable
membrane
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28
Osmosis and Osmotic Pressure
• Osmotic Pressure – ability of osmosis to generate
enough pressure to move a volume of water
Osmotic pressure increases as the concentration
of nonpermeable solutes increases.
• Isotonic – same osmotic pressure
•Cells placed in isotonic have no net gain or loss
of water.
• Hypertonic – higher osmotic pressure (water loss)
•Cells placed in hypertonic solution lose water.
• Hypotonic – lower osmotic pressure (water gain)
•Cells placed in hypotonic solution gain water.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
© David M. Phillips/Visuals Unlimited
(b)
(a)
(c)
What is a hypotonic solution?
the solution has a lower solute concentration than the cell so
water moves into the cell causing plant cells to swell and
animal cells to swell and burst
what is isotonic solutuin?
The concentration of solutes is equal inside and outside the cell
so water moves across the membrane in both directions
maintaining cell size
What is hypertonic solution?
The solution has a higher solute concentration than the cell so
water moves out of the cell and into the solution causing the
cell to plasmolyze
(following slide shows) examples
29
Solutions
30
0.9% NaCl (normal saline) isotonic
0.25% NaCl hypotonic—lower
solute concentration
0.45% NaCl hypotonic
2.5% dextrose hypotonic
Lactated Ringer's solution isotonic
D5W (acts as a hypotonic solution
in body) isotonic
D5 NaCl hypertonic
D5 in Lactated Ringer's hypertonic
D5 0.45% NaCl hypertonic
31
Filtration
• Smaller molecules are forced through porous membranes
• Hydrostatic pressure important in the body—think kidneys and low B/P
• Molecules leaving blood capillaries Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Capillary wall
Larger molecules
Smaller molecules
Blood
pressure Blood
flow
Tissue fluid
32
Active Transport
• Carrier molecules transport substances across a membrane from regions of
lower concentration to regions of higher concentration
• Requires energy
• Sugars, amino acids, sodium ions, potassium ions, etc. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Carrier protein Binding site
(a)
(b)
Cell m
em
bra
ne
Carrier protein
with altered shape
Phospholipid
molecules Transported
particle
Cellular
energy
Region of higher
concentration
Region of lower
concentration
33
Active Transport:
Sodium-Potassium Pump
• Active transport mechanism
• Creates balance by “pumping” three (3) sodium
(Na+) OUT and two (2) potassium (K+) INTO
the cell
• 3:2 ratio
34
Endocytosis
• Cell engulfs a substance by forming a vesicle around the
substance does not actually cross the cell membrane
• Three types:
• Pinocytosis – substance is mostly water
• Phagocytosis – substance is a solid
• Receptor-mediated endocytosis – requires the substance
to bind to a membrane-bound receptor
Nucleus Nucleolus
V esicle Cell
membrane
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35 Cytoplasm
V esicle
(a) (b) (c) (d)
Receptor
protein
Cell
membrane
Molecules
outside cell
Cell
membrane
indenting
Receptor-ligand
combination
Particle
Phagocytized
particle
Cell
membrane
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•Receptor-mediated endocytosis – requires the
substance to bind to a membrane-bound receptor
36
Exocytosis
• Reverse of endocytosis
• Substances in a vesicle fuse with cell membrane
• Contents released outside the cell
• Release of neurotransmitters from nerve cells
Nucleus
Endoplasmic
reticulum
Golgi
apparatus
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37
Transcytosis
• Endocytosis followed by exocytosis
• Transports a substance rapidly through a cell
• HIV crossing a cell layer
V iruses bud
HIV
Exocytosis
Receptor-mediated endocytosis
HIV-infected
white blood cells Anal or
vaginal canal
Lining of anus
or vagina
(epithelial cells)
Virus infects
white blood cells on
other side of lining
Receptor-mediated
endocytosis
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Cell
membrane
38
3.4: The Cell Cycle
• Series of changes a cell
undergoes from the time it
forms until the time it divide
• Stages:
• Interphase
• Mitosis
• Cytokinesis
Apoptosis
G2 phase
Cytokinesis
Restriction
checkpoint
Remain
specialized
Proceed
to division
S phase:
genetic
material
replicates
G1 phase
cell growth
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39
Interphase
• Very active period
• Cell grows
• Cell maintains routine functions
• Cell replicates genetic material to prepare for nuclear division
• Cell synthesizes new organelles to prepare for cytoplasmic
division
• Phases:
• G phases – cell grows and synthesizes structures other than
DNA
• S phase – cell replicates DNA
40
Mitotic Cell Division
• Produces two daughter cells from an original (non sex) somatic
cell-each with 46 chromosomes.
• Nucleus divides – mitosis
• Cytoplasm divides – cytokinesis
• Phases of mitosis:
• Prophase – chromosomes form; nuclear envelope disappears
• Metaphase – chromosomes align midway between
centrioles
• Anaphase – chromosomes separate and move to centrioles
• Telophase – chromatin forms; nuclear envelope forms
41
Mitosis
Telophase and Cytokinesis
o cells. Nuclear envelopes begin to
reassemble around two daughter
nuclei. Chromosomes decondense.
Spindle disappears. Division of
the cytoplasm into two
Anaphase
Sister chromatids separate to
opposite poles of cell. Events
begin which lead to cytokinesis. Metaphase
Chromosomes align along
equator, or metaphase plate
of cell.
Prophase
Chromosomes condense and
become visible. Nuclear
envelope and nucleolus
disperse. Spindle apparatus
forms.
Late Interphase
Cell has passed the
restriction checkpoint
and completed DNA
replication, as well as
replication of centrioles
and mitochondria, and
synthesis of extra
membrane.
Early Interphase
of daughter cells—
a time of normal cell
growth and function.
Cleavage
furrow
Nuclear
envelopes
Nuclear envelope Chromatin
fibers
Chromosomes
Spindle fiber
Centromere
Aster
Centrioles
Late prophase
Sister
chromatids
Microtubules
Mitosis
Cytokinesis
S phase
G1 phase
Interphase
Restriction
checkpoint
(a)
(b)
(c) (d)
(e)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
© Ed Reschke
G2 phase
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42
Mitosis is a continual process of --
prophase—
metaphase—
anaphase---
telophase
See box at bottom of page 109
43
Cytoplasmic Division
• Also known as cytokinesis
• Begins during anaphase
• Continues through telophase
• Contractile ring pinches cytoplasm in half
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44
3.5: Control of Cell Division
• Cell division capacities vary greatly among cell types • Skin and blood cells divide often and continually
• Neuron cells divide a specific number of times then cease
• Chromosome tips (telomeres) that shorten with each mitosis
provide a mitotic clock
• Cells divide to provide a more favorable surface area to
volume relationship
• Growth factors and hormones stimulate cell division—page 112 • Hormones stimulate mitosis of smooth muscle cells in uterus
• Epidermal growth factor stimulates growth of new skin
• Tumors are the consequence of a loss of cell cycle control
• Contact (density dependent) inhibition
45
Tumors
• Two types of tumors:
• Benign – usually remains
localized
• Malignant – invasive and can
metastasize; cancerous
• Two major types of genes
cause cancer:
• Oncogenes – activate other
genes that increase cell division
• Tumor suppressor genes –
normally regulate mitosis; if
inactivated they are unable to
regulate mitosis
• Cells are now known as
“immortal”
Normal cells
(with hairlike cilia)
Cancer cells
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© Tony Brain/Photo Researchers, Inc.;
46
3.6: Stem and Progenitor Cells
• Differentiation: specialization of cells
• Stem cell:--retain the ability to divide repeatedly
• Can divide to form two new stem cells
• Self-renewal
• Can divide to form a stem cell and a progenitor cell
• Totipotent – can give rise to every cell type
• Pluripotent – can give rise to a restricted number of cell types
• Progenitor cell:--intermediate between a stem cell and differentiated cell
• Committed cell
• Can divide to become any of a restricted number of cells
• Pluripotent vs. totipotent p. 113-114
47
Stem and Progenitor Cells
one or more steps
Sperm
Egg
Fertilized
egg
Stem cell
Stem cell
Progenitor cell
Progenitor
cell
Progenitor
cell
Blood cells and platelets
Fibroblasts (a connective tissue cells)
Bone cells
Progenitor
cell
Astrocyte
Neuron
Skin cell
Sebaceous
gland cell
produces another stem cell
(self-renewal)
Progenitor
cell
Progenitor
cell
Progenitor
cell
Progenitor
cell
Progenitor
cell
Progenitor
cell
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48
3.1 From Science to Technology
Stem cells to Study and Treat Diseases
Page 116
49
3.7: Cell Death
Apoptosis:
• Programmed cell death
• Acts as a protective mechanism
• Is a continuous process
page 117 and bullets on page 114
Blebs
Cell fragments
Phagocyte attacks
and engulfs cell
remnants. Cell
components are
degraded.
Caspases destroy various
proteins and other cell components.
Cell becomes deformed.
Death receptor on doomed cell
binds signal molecule. Caspases
are activated within.
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© Peter Skinner/Photo Researchers, Inc.
50
Important Points in Chapter 3: Outcomes to be Assessed
3.3: Movements Into and Out of the Cell
Explain how substances move into and out of cells.
3.4: The Cell Cycle
Describe the cell cycle.
Explain how a cell divides.
3.5: Control of Cell Division
Describe several controls of cell division.