Ch03 b,living units.mission
Transcript of Ch03 b,living units.mission
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Human Anatomy & PhysiologySEVENTH EDITION
Elaine N. Marieb
Katja Hoehn
PowerPoint® Lecture Slides
prepared by Vince Austin,
Bluegrass Technical
and Community College
C H
A P
T E
R
3Cells: The Living Units
P A R T B
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Active Transport
Uses ATP to move solutes across a membrane
Requires carrier proteins
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Types of Active Transport
Symport system – two substances are moved
across a membrane in the same direction
Antiport system – two substances are moved
across a membrane in opposite directions
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Types of Active Transport
Primary active transport – hydrolysis of ATP
phosphorylates the transport protein causing
conformational change
Secondary active transport – use of an exchange
pump (such as the Na+-K+ pump) indirectly to
drive the transport of other solutes
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Types of Active Transport
Figure 3.11
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Vesicular Transport
Transport of large particles and macromolecules
across plasma membranes
Exocytosis – moves substance from the cell
interior to the extracellular space
Endocytosis – enables large particles and
macromolecules to enter the cell
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Vesicular Transport
Transcytosis – moving substances into, across, and
then out of a cell
Vesicular trafficking – moving substances from
one area in the cell to another
Phagocytosis – pseudopods engulf solids and bring
them into the cell’s interior
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Vesicular Transport
Fluid-phase endocytosis – the plasma membrane
infolds, bringing extracellular fluid and solutes into
the interior of the cell
Receptor-mediated endocytosis – clathrin-coated
pits provide the main route for endocytosis and
transcytosis
Non-clathrin-coated vesicles – caveolae that are
platforms for a variety of signaling molecules
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Exocytosis
Figure 3.12a
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Clathrin-Mediated Endocytosis
Figure 3.13a
Recycling of
membrane and
receptors (if present)
to plasma membrane
CytoplasmExtracellular
fluid
Extracellular
fluid
Plasma
membrane
Detachment
of clathrin-
coated
vesicle
Clathrin-
coated
vesicle
Uncoating
Uncoated
vesicle
Uncoated
vesicle
fusing with
endosome
To lysosome
for digestion
and release
of contents
Transcytosis
Endosome
Exocytosis
of vesicle
contents
Clathrin-
coated
pit
Plasma
membrane
Ingested
substance
Clathrin
protein
(a) Clathrin-mediated endocytosis
2
1
3
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Clathrin-Mediated Endocytosis
Figure 3.13a
CytoplasmExtracellular
fluid
Extracellular
fluid
Plasma
membrane
Clathrin-
coated
pit
Plasma
membrane
Ingested
substance
(a) Clathrin-mediated endocytosis
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Clathrin-Mediated Endocytosis
Figure 3.13a
CytoplasmExtracellular
fluid
Extracellular
fluid
Plasma
membrane
Detachment
of clathrin-
coated
vesicle
Clathrin-
coated
vesicle
Clathrin-
coated
pit
Plasma
membrane
Ingested
substance
(a) Clathrin-mediated endocytosis
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Clathrin-Mediated Endocytosis
Figure 3.13a
CytoplasmExtracellular
fluid
Extracellular
fluid
Plasma
membrane
Detachment
of clathrin-
coated
vesicle
Clathrin-
coated
vesicle
Uncoating
Uncoated
vesicle
Uncoated
vesicle
fusing with
endosome
Endosome
Clathrin-
coated
pit
Plasma
membrane
Ingested
substance
Clathrin
protein
(a) Clathrin-mediated endocytosis
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Clathrin-Mediated Endocytosis
Figure 3.13a
Recycling of
membrane and
receptors (if present)
to plasma membrane
CytoplasmExtracellular
fluid
Extracellular
fluid
Plasma
membrane
Detachment
of clathrin-
coated
vesicle
Clathrin-
coated
vesicle
Uncoating
Uncoated
vesicle
Uncoated
vesicle
fusing with
endosome
Endosome
Clathrin-
coated
pit
Plasma
membrane
Ingested
substance
Clathrin
protein
(a) Clathrin-mediated endocytosis
1
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Clathrin-Mediated Endocytosis
Figure 3.13a
CytoplasmExtracellular
fluid
Extracellular
fluid
Plasma
membrane
Detachment
of clathrin-
coated
vesicle
Clathrin-
coated
vesicle
Uncoating
Uncoated
vesicle
Uncoated
vesicle
fusing with
endosome
To lysosome
for digestion
and release
of contents
Endosome
Clathrin-
coated
pit
Plasma
membrane
Ingested
substance
Clathrin
protein
(a) Clathrin-mediated endocytosis
2
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Clathrin-Mediated Endocytosis
Figure 3.13a
CytoplasmExtracellular
fluid
Extracellular
fluid
Plasma
membrane
Detachment
of clathrin-
coated
vesicle
Clathrin-
coated
vesicle
Uncoating
Uncoated
vesicle
Uncoated
vesicle
fusing with
endosome
Transcytosis
Endosome
Exocytosis
of vesicle
contents
Clathrin-
coated
pit
Plasma
membrane
Ingested
substance
Clathrin
protein
(a) Clathrin-mediated endocytosis
3
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Clathrin-Mediated Endocytosis
Figure 3.13a
Recycling of
membrane and
receptors (if present)
to plasma membrane
CytoplasmExtracellular
fluid
Extracellular
fluid
Plasma
membrane
Detachment
of clathrin-
coated
vesicle
Clathrin-
coated
vesicle
Uncoating
Uncoated
vesicle
Uncoated
vesicle
fusing with
endosome
To lysosome
for digestion
and release
of contents
Transcytosis
Endosome
Exocytosis
of vesicle
contents
Clathrin-
coated
pit
Plasma
membrane
Ingested
substance
Clathrin
protein
(a) Clathrin-mediated endocytosis
2
1
3
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Phagocytosis
Figure 3.13b
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Receptor Mediated Endocytosis
Figure 3.13c
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Passive Membrane Transport – Review
Process Energy Source Example
Simple diffusion Kinetic energy Movement of O2 through membrane
Facilitated diffusion Kinetic energy Movement of glucose into cells
Osmosis Kinetic energy Movement of H2O in & out of cells
Filtration Hydrostatic pressure Formation of kidney filtrate
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Active Membrane Transport – Review
Process Energy Source Example
Active transport of solutes ATPMovement of ions across
membranes
Exocytosis ATP Neurotransmitter secretion
Endocytosis ATP White blood cell phagocytosis
Fluid-phase endocytosis ATP Absorption by intestinal cells
Receptor-mediated endocytosis ATP Hormone and cholesterol uptake
Endocytosis via caveoli ATP Cholesterol regulation
Endocytosis via coatomer
vesiclesATP
Intracellular trafficking of
molecules
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Membrane Potential
Voltage across a membrane
Resting membrane potential – the point where K+
potential is balanced by the membrane potential
Ranges from –20 to –200 mV
Results from Na+ and K+ concentration gradients across the membrane
Differential permeability of the plasma membrane to Na+ and K+
Steady state – potential maintained by active transport of ions
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Generation and Maintenance of Membrane
Potential
PLAY InterActive Physiology ®:
Nervous System I: The Membrane Potential
Figure 3.15
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Cell Adhesion Molecules (CAMs)
Anchor cells to the extracellular matrix
Assist in movement of cells past one another
Rally protective white blood cells to injured or
infected areas
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Roles of Membrane Receptors
Contact signaling – important in normal development and immunity
Electrical signaling – voltage-regulated “ion gates” in nerve and muscle tissue
Chemical signaling – neurotransmitters bind to chemically gated channel-linked receptors in nerve and muscle tissue
G protein-linked receptors – ligands bind to a receptor which activates a G protein, causing the release of a second messenger, such as cyclic AMP
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Operation of a G Protein
An extracellular ligand (first messenger), binds to
a specific plasma membrane protein
The receptor activates a G protein that relays the
message to an effector protein
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Operation of a G Protein
The effector is an enzyme that produces a second
messenger inside the cell
The second messenger activates a kinase
The activated kinase can trigger a variety of
cellular responses
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Operation of a G Protein
Figure 3.16
Extracellular fluid
Cytoplasm
Inactive
second
messenger
Cascade of cellular responses
(metabolic and structural changes)
Effector
(e.g., enzyme)
Activated
(phosphorylated)
kinases
First messenger
(ligand)
Active
second
messenger
(e.g., cyclic
AMP)
Membrane
receptor
G protein
1
2
3 4
5
6
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Operation of a G Protein
Figure 3.16
Extracellular fluid
Cytoplasm
First messenger
(ligand)
Membrane
receptor
1
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Operation of a G Protein
Figure 3.16
Extracellular fluid
Cytoplasm
First messenger
(ligand)
Membrane
receptor
G protein
1
2
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Operation of a G Protein
Figure 3.16
Extracellular fluid
Cytoplasm
Effector
(e.g., enzyme)
First messenger
(ligand)
Membrane
receptor
G protein
1
2
3
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Operation of a G Protein
Figure 3.16
Extracellular fluid
Cytoplasm
Inactive
second
messenger
Effector
(e.g., enzyme)
First messenger
(ligand)
Active
second
messenger
(e.g., cyclic
AMP)
Membrane
receptor
G protein
1
2
3 4
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Operation of a G Protein
Figure 3.16
Extracellular fluid
Cytoplasm
Inactive
second
messenger
Effector
(e.g., enzyme)
Activated
(phosphorylated)
kinases
First messenger
(ligand)
Active
second
messenger
(e.g., cyclic
AMP)
Membrane
receptor
G protein
1
2
3 4
5
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Operation of a G Protein
Figure 3.16
Extracellular fluid
Cytoplasm
Inactive
second
messenger
Cascade of cellular responses
(metabolic and structural changes)
Effector
(e.g., enzyme)
Activated
(phosphorylated)
kinases
First messenger
(ligand)
Active
second
messenger
(e.g., cyclic
AMP)
Membrane
receptor
G protein
1
2
3 4
5
6
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Cytoplasm
Cytoplasm – material between plasma membrane
and the nucleus
Cytosol – largely water with dissolved protein,
salts, sugars, and other solutes
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Cytoplasm
Cytoplasmic organelles – metabolic machinery of
the cell
Inclusions – chemical substances such as
glycosomes, glycogen granules, and pigment
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Cytoplasmic Organelles
Specialized cellular compartments
Membranous
Mitochondria, peroxisomes, lysosomes,
endoplasmic reticulum, and Golgi apparatus
Nonmembranous
Cytoskeleton, centrioles, and ribosomes
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Mitochondria
Double membrane structure with shelf-like cristae
Provide most of the cell’s ATP via aerobic cellular
respiration
Contain their own DNA and RNA
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Mitochondria
Figure 3.17a, b
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Ribosomes
Granules containing protein and rRNA
Site of protein synthesis
Free ribosomes synthesize soluble proteins
Membrane-bound ribosomes synthesize proteins to
be incorporated into membranes
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Endoplasmic Reticulum (ER)
Interconnected tubes and parallel membranes
enclosing cisternae
Continuous with the nuclear membrane
Two varieties – rough ER and smooth ER
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Endoplasmic Reticulum (ER)
Figure 3.18a, c
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Rough (ER)
External surface studded with ribosomes
Manufactures all secreted proteins
Responsible for the synthesis of integral membrane
proteins and phospholipids for cell membranes
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Signal Mechanism of Protein Synthesis
mRNA – ribosome complex is directed to rough
ER by a signal-recognition particle (SRP)
SRP is released and polypeptide grows into
cisternae
The protein is released into the cisternae and sugar
groups are added
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Signal Mechanism of Protein Synthesis
The protein folds into a three-dimensional
conformation
The protein is enclosed in a transport vesicle and
moves toward the Golgi apparatus
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Signal Mechanism of Protein Synthesis
Figure 3.19
Cytosol
Ribosomes
mRNA
Coatomer-
coated
transport
vesicle
Transport
vesicle
budding off
Released
glycoprotein
ER
cisterna
ER
membrane
Signal-
recognition
particle
(SRP)
Signal
sequenceReceptor
site
Sugar
group
Signal
sequence
removedGrowing
polypeptide
1
2
34
5
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Signal Mechanism of Protein Synthesis
Figure 3.19
Cytosol
mRNA
ER
cisterna
ER
membrane
Signal-
recognition
particle
(SRP)
Signal
sequenceReceptor
site
1
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Signal Mechanism of Protein Synthesis
Figure 3.19
Cytosol
mRNA
ER
cisterna
ER
membrane
Signal-
recognition
particle
(SRP)
Signal
sequenceReceptor
site Growing
polypeptide
1
2
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Signal Mechanism of Protein Synthesis
Figure 3.19
Cytosol
Ribosomes
mRNA
ER
cisterna
ER
membrane
Signal-
recognition
particle
(SRP)
Signal
sequenceReceptor
site
Signal
sequence
removedGrowing
polypeptide
1
2
3
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Signal Mechanism of Protein Synthesis
Figure 3.19
Cytosol
Ribosomes
mRNA
Released
glycoprotein
ER
cisterna
ER
membrane
Signal-
recognition
particle
(SRP)
Signal
sequenceReceptor
site
Signal
sequence
removedGrowing
polypeptide
1
2
34
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Signal Mechanism of Protein Synthesis
Figure 3.19
Cytosol
Ribosomes
mRNA
Transport
vesicle
budding off
Released
glycoprotein
ER
cisterna
ER
membrane
Signal-
recognition
particle
(SRP)
Signal
sequenceReceptor
site
Sugar
group
Signal
sequence
removedGrowing
polypeptide
1
2
34
5
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Signal Mechanism of Protein Synthesis
Figure 3.19
Cytosol
Ribosomes
mRNA
Coatomer-
coated
transport
vesicle
Transport
vesicle
budding off
Released
glycoprotein
ER
cisterna
ER
membrane
Signal-
recognition
particle
(SRP)
Signal
sequenceReceptor
site
Sugar
group
Signal
sequence
removedGrowing
polypeptide
1
2
34
5
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Smooth ER
Tubules arranged in a looping network
Catalyzes the following reactions in various organs
of the body
In the liver – lipid and cholesterol metabolism,
breakdown of glycogen and, along with the
kidneys, detoxification of drugs
In the testes – synthesis of steroid-based hormones
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Smooth ER
Catalyzes the following reactions in various organs
of the body (continued)
In the intestinal cells – absorption, synthesis, and
transport of fats
In skeletal and cardiac muscle – storage and release
of calcium