Membrane Dynamics Energy Transfer in Living Cells Figure 516 ATP Secondary active transport Primary active transport Metabolism The chemical bond energy is converted into highenergy bonds of ATP through ID: 463907
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Slide1
Chapter 5b
Membrane DynamicsSlide2
Energy Transfer in Living Cells
Figure 5-16
ATP
Secondary active transport
Primary active transport
Metabolism
The chemical bond energy is converted
into high-energy bonds of ATP through
the process of metabolism.
The energy in the high-energy phosphate
bond of ATP is used to move K+ and Na+against their concentration gradients.This creates potential energy stored in the ion concentration gradients.
The energy of the Na+ gradient can be used to move other molecules across the cell membrane against their concentration gradients.
Energy is imported into the cell asenergy stored in chemical bonds of nutrients such as glucose.
Glucose
Pyruvate
CAcycle
Heat
H2O
CO2
ADP+Pi
O2
High [K+]
Low [Na+]
Na+
Na+
Glycolysis
ETS
K+
K+
2 Cl–
Low [K+]
High [Na+]
Glucose
ATP
ATP
ETS
= Electron transport system
= Citric acid cycle
CAcycle
KEYSlide3
Carrier-Mediated Transport
Specificity
Competition
SaturationTransport maximumSlide4
Carrier-Mediated Transport Competition
Figure 5-17Slide5
Carrier-Mediated Transport Competition
Figure 5-18
(b)
Maltose
(a)
The
GLUT transporter
Maltose
Glucose
Glucose
GLUT
transporterIntracellular fluid
Extracellular fluidSlide6
Carrier-Mediated Transport Saturation
Figure 5-19Slide7
Vesicular Transport
Phagocytosis
Cell engulfs bacterium or other particle into
phagosomeEndocytosisMembrane surface indents and forms vesicles
Active process that can be nonselective (pinocytosis) or highly selectivePotocytosis uses
caveolaeReceptor-mediated uses clathrin-coated pitsSlide8
Phagocytosis
Figure 5-20
1
Bacterium
Lysosome
Phagocyte
The phagocytic white blood
cell encounters a bacterium
that binds to the cell
membrane.
The phagocyte uses itscytoskeleton to push its
cell membrane around thebacterium, creating a largevesicle, the phagosome. The phagosome containing the bacterium separates from the cell membrane andmoves into the cytoplasm.
The phagosome fuses with lysosomes containing digestive enzymes.
The bacterium is killedand digested within the
vesicle.
23
4
5Slide9
Phagocytosis
Figure 5-20, step 1
1
Bacterium
Lysosome
Phagocyte
The phagocytic white blood
cell encounters a bacterium
that binds to the cell
membrane.Slide10
Phagocytosis
Figure 5-20, steps 1–2
1
Bacterium
Lysosome
Phagocyte
The phagocytic white blood
cell encounters a bacterium
that binds to the cell
membrane.
The phagocyte uses itscytoskeleton to push its
cell membrane around thebacterium, creating a largevesicle, the phagosome. 2Slide11
Phagocytosis
Figure 5-20, steps 1–3
1
Bacterium
Lysosome
Phagocyte
The phagocytic white blood
cell encounters a bacterium
that binds to the cell
membrane.
The phagocyte uses itscytoskeleton to push its
cell membrane around thebacterium, creating a largevesicle, the phagosome. The phagosome containing the bacterium separates from the cell membrane andmoves into the cytoplasm.
2
3Slide12
Phagocytosis
Figure 5-20, steps 1–4
1
Bacterium
Lysosome
Phagocyte
The phagocytic white blood
cell encounters a bacterium
that binds to the cell
membrane.
The phagocyte uses itscytoskeleton to push its
cell membrane around thebacterium, creating a largevesicle, the phagosome. The phagosome containing the bacterium separates from the cell membrane andmoves into the cytoplasm.
The phagosome fuses with lysosomes containing digestive enzymes.
2
3
4Slide13
Phagocytosis
Figure 5-20, steps 1–5
1
Bacterium
Lysosome
Phagocyte
The phagocytic white blood
cell encounters a bacterium
that binds to the cell
membrane.
The phagocyte uses itscytoskeleton to push its
cell membrane around thebacterium, creating a largevesicle, the phagosome. The phagosome containing the bacterium separates from the cell membrane andmoves into the cytoplasm.
The phagosome fuses with lysosomes containing digestive enzymes.
The bacterium is killedand digested within the
vesicle.
23
4
5Slide14
Figure 5-21
Receptor-Mediated Endocytosis and Exocytosis
1
Ligand binds to membrane receptor.
Clathrin-coated
pit
Receptor
Extracellular fluid
Intracellular fluid
To lysosome or
Golgi complex
Receptor-ligand migrates to clathrin-coated pit.
Endocytosis
Vesicle loses
clathrin coat.
Ligands go to lysosomes
or Golgi for processing.
Transport vesicle
with receptors moves to the cell membrane.
Transport vesicle and cell membranefuse (membranerecycling).
Exocytosis
Clathrin
Endosome
Receptors and ligands separate.
2
3
4
5
6
7
8
9Slide15
Receptor-Mediated Endocytosis and Exocytosis
Figure 5-21, step 1
1
Ligand binds to membrane receptor.
Receptor
Extracellular fluid
Intracellular fluidSlide16
Receptor-Mediated Endocytosis and Exocytosis
Figure 5-21, steps 1–2
1
Ligand binds to membrane receptor.
Clathrin-coated
pit
Receptor
Extracellular fluid
Intracellular fluid
Receptor-ligand migrates to clathrin-coated pit.
Clathrin
2Slide17
Receptor-Mediated Endocytosis and Exocytosis
Figure 5-21, steps 1–3
1
Ligand binds to membrane receptor.
Clathrin-coated
pit
Receptor
Extracellular fluid
Intracellular fluid
Receptor-ligand migrates to clathrin-coated pit.
Endocytosis
Clathrin
2
3Slide18
Receptor-Mediated Endocytosis and Exocytosis
Figure 5-21, steps 1–4
1
Ligand binds to membrane receptor.
Clathrin-coated
pit
Receptor
Extracellular fluid
Intracellular fluid
Receptor-ligand migrates to clathrin-coated pit.
Endocytosis
Vesicle loses
clathrin coat.
Clathrin
2
3
4Slide19
Receptor-Mediated Endocytosis and Exocytosis
Figure 5-21, steps 1–5
1
Ligand binds to membrane receptor.
Clathrin-coated
pit
Receptor
Extracellular fluid
Intracellular fluid
Receptor-ligand migrates to clathrin-coated pit.
Endocytosis
Vesicle loses
clathrin coat.
Clathrin
Endosome
Receptors
and ligands separate.
2
3
4
5Slide20
Receptor-Mediated Endocytosis and Exocytosis
Figure 5-21, steps 1–6
1
Ligand binds to membrane receptor.
Clathrin-coated
pit
Receptor
Extracellular fluid
Intracellular fluid
To lysosome or
Golgi complex
Receptor-ligand migrates to clathrin-coated pit.
Endocytosis
Vesicle loses
clathrin coat.
Ligands go to lysosomes
or Golgi for processing.
ClathrinEndosome
Receptors and ligands separate.
2
3
4
5
6Slide21
Receptor-Mediated Endocytosis and Exocytosis
Figure 5-21, steps 1–7
1
Ligand binds to membrane receptor.
Clathrin-coated
pit
Receptor
Extracellular fluid
Intracellular fluid
To lysosome or
Golgi complex
Receptor-ligand migrates to clathrin-coated pit.
Endocytosis
Vesicle loses
clathrin coat.
Ligands go to lysosomes
or Golgi for processing.
Transport vesicle with receptors moves to the cell membrane.
ClathrinEndosome
Receptors and ligands separate.
2
3
4
5
6
7Slide22
Receptor-Mediated Endocytosis and Exocytosis
Figure 5-21, steps 1–8
1
Ligand binds to membrane receptor.
Clathrin-coated
pit
Receptor
Extracellular fluid
Intracellular fluid
To lysosome or
Golgi complex
Receptor-ligand migrates to clathrin-coated pit.
Endocytosis
Vesicle loses
clathrin coat.
Ligands go to lysosomes
or Golgi for processing.
Transport vesicle with receptors moves to the cell membrane.
Transport vesicle and cell membrane
fuse (membranerecycling).
ClathrinEndosome
Receptors and ligands separate.
2
3
4
5
6
7
8Slide23
Receptor-Mediated Endocytosis and Exocytosis
Figure 5-21, steps 1–9
1
Ligand binds to membrane receptor.
Clathrin-coated
pit
Receptor
Extracellular fluid
Intracellular fluid
To lysosome or
Golgi complex
Receptor-ligand migrates to clathrin-coated pit.
Endocytosis
Vesicle loses
clathrin coat.
Ligands go to lysosomes
or Golgi for processing.
Transport vesicle
with receptors moves to the cell membrane.
Transport vesicle and cell membranefuse (membranerecycling).
Exocytosis
Clathrin
Endosome
Receptors and ligands separate.
2
3
4
5
6
7
8
9Slide24
Transepithelial Transport
Polarized cells of transporting epithelia
Figure 5-22
Apical
membrane
Tight junction
Transporting
epithelial cell
Basolateral
membrane
Lumen
of intestine
or kidneyExtracellular
fluid
Transport proteinsSlide25
Transepithelial Transport of Glucose
Figure 5-23
1
[Glucose]
low
[Glucose]
high
[Glucose]
low
[Na
+] high[Na+
] low[Na+] high
ApicalmembraneBasolateralmembrane
Extracellular
fluid
Lumen of kidneyor intestine
Epithelialcell
3
2GLUT transporter
transfers glucose to ECF by facilitated diffusion.
Na+-K+- ATPase pumps
Na+ out of the cell, keepingICF Na+ concentration low.
Na
+-glucose symporterbrings glucose into cell against its gradient using energy stored in the Na
+concentration gradient.
1
2
3Slide26
Transepithelial Transport of Glucose
Figure 5-23, step 1
1
[Glucose]
low
[Glucose]
high
[Na
+
]
high[Na+] low
ApicalmembraneBasolateralmembraneExtracellular
fluidLumen of kidneyor intestine
Epithelial
cell
Na+-glucose symporterbrings glucose into cell against its gradient using energy stored in the Na
+concentration gradient.
1Slide27
Transepithelial Transport of Glucose
Figure 5-23, steps 1–2
1
[Glucose]
low
[Glucose]
high
[Glucose]
low
[Na
+] high[Na+
] lowApicalmembraneBasolateral
membraneExtracellularfluid
Lumen of kidneyor intestine
Epithelial
cellGLUT transporter
transfers glucose to ECF by facilitated diffusion.
Na+-glucose symporterbrings glucose into cell against its gradient using
energy stored in the Na+concentration gradient.
1
2
2Slide28
Transepithelial Transport of Glucose
Figure 5-23, steps 1–3
1
[Glucose]
low
[Glucose]
high
[Glucose]
low
[Na
+] high[Na+
] low[Na+] high
ApicalmembraneBasolateralmembrane
Extracellular
fluid
Lumen of kidneyor intestine
Epithelialcell
3
2GLUT transporter
transfers glucose to ECF by facilitated diffusion.
Na+-K+- ATPase pumps
Na+ out of the cell, keepingICF Na+ concentration low.
Na
+-glucose symporterbrings glucose into cell against its gradient using energy stored in the Na
+concentration gradient.
1
2
3Slide29
Transcytosis Across the Capillary Endothelium
Figure 5-24
Plasma proteins
Red
blood
cell
Endocytosis
Vesicular
transport
Exocytosis
Caveolae
Interstitial fluidCapillary
endothelium
Plasma proteins are concentrated
in caveolae, which then undergo
endocytosis and form vesicles.
Vesicles cross the cell with helpfrom the cytoskeleton.
Vesicle contents are released intointerstitial fluid by exocytosis.
2
1
2
3
31