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. MariebKatja 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 ofmembrane andreceptors (if present)to plasma membrane
CytoplasmExtracellular fluid
Extracellularfluid
Plasmamembrane
Detachmentof clathrin-coatedvesicle
Clathrin-coatedvesicle
Uncoating
Uncoatedvesicle
Uncoatedvesiclefusing withendosome
To lysosomefor digestionand releaseof contents
Transcytosis
Endosome
Exocytosisof vesiclecontents
Clathrin-coatedpit
Plasmamembrane
Ingestedsubstance
Clathrinprotein
(a) Clathrin-mediated endocytosis
2
1
3
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Clathrin-Mediated Endocytosis
Figure 3.13a
CytoplasmExtracellular fluid
Extracellularfluid
Plasmamembrane
Clathrin-coatedpit
Plasmamembrane
Ingestedsubstance
(a) Clathrin-mediated endocytosis
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Clathrin-Mediated Endocytosis
Figure 3.13a
CytoplasmExtracellular fluid
Extracellularfluid
Plasmamembrane
Detachmentof clathrin-coatedvesicle
Clathrin-coatedvesicle
Clathrin-coatedpit
Plasmamembrane
Ingestedsubstance
(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
Extracellularfluid
Plasmamembrane
Detachmentof clathrin-coatedvesicle
Clathrin-coatedvesicle
Uncoating
Uncoatedvesicle
Uncoatedvesiclefusing withendosome
Endosome
Clathrin-coatedpit
Plasmamembrane
Ingestedsubstance
Clathrinprotein
(a) Clathrin-mediated endocytosis
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Clathrin-Mediated Endocytosis
Figure 3.13a
Recycling ofmembrane andreceptors (if present)to plasma membrane
CytoplasmExtracellular fluid
Extracellularfluid
Plasmamembrane
Detachmentof clathrin-coatedvesicle
Clathrin-coatedvesicle
Uncoating
Uncoatedvesicle
Uncoatedvesiclefusing withendosome
Endosome
Clathrin-coatedpit
Plasmamembrane
Ingestedsubstance
Clathrinprotein
(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
Extracellularfluid
Plasmamembrane
Detachmentof clathrin-coatedvesicle
Clathrin-coatedvesicle
Uncoating
Uncoatedvesicle
Uncoatedvesiclefusing withendosome
To lysosomefor digestionand releaseof contents
Endosome
Clathrin-coatedpit
Plasmamembrane
Ingestedsubstance
Clathrinprotein
(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
Extracellularfluid
Plasmamembrane
Detachmentof clathrin-coatedvesicle
Clathrin-coatedvesicle
Uncoating
Uncoatedvesicle
Uncoatedvesiclefusing withendosome
Transcytosis
Endosome
Exocytosisof vesiclecontents
Clathrin-coatedpit
Plasmamembrane
Ingestedsubstance
Clathrinprotein
(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 ofmembrane andreceptors (if present)to plasma membrane
CytoplasmExtracellular fluid
Extracellularfluid
Plasmamembrane
Detachmentof clathrin-coatedvesicle
Clathrin-coatedvesicle
Uncoating
Uncoatedvesicle
Uncoatedvesiclefusing withendosome
To lysosomefor digestionand releaseof contents
Transcytosis
Endosome
Exocytosisof vesiclecontents
Clathrin-coatedpit
Plasmamembrane
Ingestedsubstance
Clathrinprotein
(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 vesicles
ATPIntracellular 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
PLAYPLAY 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
Inactivesecondmessenger
Cascade of cellular responses(metabolic and structural changes)
Effector(e.g., enzyme)
Activated(phosphorylated)kinases
First messenger(ligand)
Activesecondmessenger(e.g., cyclicAMP)
Membranereceptor
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)
Membranereceptor
1
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Operation of a G Protein
Figure 3.16
Extracellular fluid
Cytoplasm
First messenger(ligand)
Membranereceptor
G protein
1
2
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Operation of a G Protein
Figure 3.16
Extracellular fluid
Cytoplasm
Effector(e.g., enzyme)
First messenger(ligand)
Membranereceptor
G protein
1
2
3
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Operation of a G Protein
Figure 3.16
Extracellular fluid
Cytoplasm
Inactivesecondmessenger
Effector(e.g., enzyme)
First messenger(ligand)
Activesecondmessenger(e.g., cyclicAMP)
Membranereceptor
G protein
1
2
3 4
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Operation of a G Protein
Figure 3.16
Extracellular fluid
Cytoplasm
Inactivesecondmessenger
Effector(e.g., enzyme)
Activated(phosphorylated)kinases
First messenger(ligand)
Activesecondmessenger(e.g., cyclicAMP)
Membranereceptor
G protein
1
2
3 4
5
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Operation of a G Protein
Figure 3.16
Extracellular fluid
Cytoplasm
Inactivesecondmessenger
Cascade of cellular responses(metabolic and structural changes)
Effector(e.g., enzyme)
Activated(phosphorylated)kinases
First messenger(ligand)
Activesecondmessenger(e.g., cyclicAMP)
Membranereceptor
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-coatedtransportvesicle
Transportvesiclebudding off
Releasedglycoprotein
ERcisterna
ERmembrane
Signal-recognitionparticle(SRP)
Signalsequence
Receptorsite
Sugargroup
SignalsequenceremovedGrowing
polypeptide
1
2
34
5
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Signal Mechanism of Protein Synthesis
Figure 3.19
Cytosol
mRNA
ERcisterna
ERmembrane
Signal-recognitionparticle(SRP)
Signalsequence
Receptorsite
1
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Signal Mechanism of Protein Synthesis
Figure 3.19
Cytosol
mRNA
ERcisterna
ERmembrane
Signal-recognitionparticle(SRP)
Signalsequence
Receptorsite Growing
polypeptide
1
2
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Signal Mechanism of Protein Synthesis
Figure 3.19
Cytosol
Ribosomes
mRNA
ERcisterna
ERmembrane
Signal-recognitionparticle(SRP)
Signalsequence
Receptorsite
SignalsequenceremovedGrowing
polypeptide
1
2
3
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Signal Mechanism of Protein Synthesis
Figure 3.19
Cytosol
Ribosomes
mRNA
Releasedglycoprotein
ERcisterna
ERmembrane
Signal-recognitionparticle(SRP)
Signalsequence
Receptorsite
SignalsequenceremovedGrowing
polypeptide
1
2
34
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Signal Mechanism of Protein Synthesis
Figure 3.19
Cytosol
Ribosomes
mRNA
Transportvesiclebudding off
Releasedglycoprotein
ERcisterna
ERmembrane
Signal-recognitionparticle(SRP)
Signalsequence
Receptorsite
Sugargroup
SignalsequenceremovedGrowing
polypeptide
1
2
34
5
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Signal Mechanism of Protein Synthesis
Figure 3.19
Cytosol
Ribosomes
mRNA
Coatomer-coatedtransportvesicle
Transportvesiclebudding off
Releasedglycoprotein
ERcisterna
ERmembrane
Signal-recognitionparticle(SRP)
Signalsequence
Receptorsite
Sugargroup
SignalsequenceremovedGrowing
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