Figure 5.1 Membrane Molecular Structure
Outside of cell
Extracellular
matrix
Phospholipid
Cytoskeleton
Inside of cell
In-Text Art, Ch. 5, p. 64
“Head”
“Tails”
In-Text Art, Ch. 5, p. 65
Outside of cell
(aqueous)
Hydrophobic
interior of
bilayer
Inside of cell
(aqueous)
In-Text Art, Ch. 5, p. 66
Cells
Figure 5.2 Rapid Diffusion of Membrane Proteins (Part 1)
Proteins embedded in a membrane can diffuse freely
within the membrane.
Membrane
proteins
Mouse cell
Human cell
Figure 5.2 Rapid Diffusion of Membrane Proteins (Part 2)
Proteins embedded in a membrane can diffuse freely
within the membrane.
Membrane proteins
Mouse cell
Human cell
Heterokaryon
Membrane proteins can diffuse rapidly in the plane of
the membrane.
Figure 5.2 Rapid Diffusion of Membrane Proteins (Part 3)
The experiment was repeated at various temperatures with the
following results:
Temperature (C)
0
15
20
26
Cells with mixed
proteins (%)
0
8
42
77
Plot these data on a graph of Percentage Mixed vs. Temperature.
Explain these data, relating the results to the concepts of
diffusion and membrane fluidity.
Figure 5.3 Osmosis Can Modify the Shapes of Cells (Part 1)
Hypertonic on the
outside (concentrated
solutes outside)
Inside
of cell
Outside
of cell
Isotonic
(equivalent solute
concentration)
Hypotonic on the
outside (dilute
solutes outside)
Figure 5.3 Osmosis Can Modify the Shapes of Cells (Part 2)
Hypertonic on the
outside (concentrated
solutes outside)
Animal cell
(red blood cells)
Isotonic
(equivalent solute
concentration)
Hypotonic on the
outside (dilute
solutes outside)
Figure 5.3 Osmosis Can Modify the Shapes of Cells (Part 3)
Hypertonic on the
outside (concentrated
solutes outside)
Plant cell
(leaf epithelial
cells)
Isotonic
(equivalent solute
concentration)
Hypotonic on the
outside (dilute
solutes outside)
Figure 5.4 A Ligand-Gated Channel Protein Opens in Response to a Stimulus
Outside of cell
Stimulus
molecule
(ligand)
Binding
site
Hydrophobic
interior of bilayer
Channel
protein
Closed
channel
Inside of cell
Hydrophilic
pore
Figure 5.5 Aquaporins Increase Membrane Permeability to Water (Part 1)
Aquaporin increases membrane permeability to water.
Aquaporin
mRNA
Aquaporin
channel
Protein
synthesis
Figure 5.5 Aquaporins Increase Membrane Permeability to Water (Part 2)
Aquaporin increases membrane permeability to water.
Aquaporin
mRNA
Aquaporin
channel
Protein
synthesis
3.5 minutes in
hypotonic solution
Aquaporin increases the rate of water diffusion across
the cell membrane.
Figure 5.5 Aquaporins Increase Membrane Permeability to Water (Part 3)
Oocytes were injected with aquaporin mRNA (red circles) or a solution
without mRNA (blue circles). Water permeability was tested by incubating
the oocytes in hypotonic solution and measuring cell volume.
After time X in the upper curve, intact oocytes were not visible:
Relative volume
X
With mRNA
Without mRNA
Time (min)
A. Why did the cells increase in volume?
B. What happened at time X?
C. Calculate the relative rates (volume increase per minute) of swelling
in the control and experimental curves. What does this show about
the effectiveness of mRNA injection?
Figure 5.6 A Carrier Protein Facilitates Diffusion (Part 1)
Outside of cell
High glucose
concentration
Glucose
Glucose
carrier protein
Inside of cell
Low glucose
concentration
Rate of diffusion
into the cell
Figure 5.6 A Carrier Protein Facilitates Diffusion (Part 2)
Glucose concentration
outside the cell
Figure 5.7 Primary Active Transport: The Sodium–Potassium Pump
Outside of cell
High Na+ concentration,
low K+ concentration
Na+
Na+– K+ pump
K+
K+
ATP
Na+
Pi
ADP
Pi
Pi
Pi
K+
Inside of cell
High K+ concentration,
low Na+ concentration
Figure 5.8 Endocytosis and Exocytosis (Part 1)
(A) Endocytosis
Outside of cell
Plasma membrane
Inside of cell
Endocytotic vesicle
Figure 5.8 Endocytosis and Exocytosis (Part 2)
(B) Exocytosis
Secretory vesicle
Figure 5.9 Receptor-Mediated Endocytosis (Part 1)
Outside
of cell
Specific
substance
binding to
receptor
proteins
Cytoplasm
Clathrin
molecules
Coated
pit
Coated
vesicle
Figure 5.9 Receptor-Mediated Endocytosis (Part 2)
Outside
of cell
Specific
substance
binding to
receptor
proteins
Coated
pit
Cytoplasm
Coated
vesicle
Clathrin
molecules
Figure 5.10 Chemical Signaling Concepts
Secreting cell
Receptor
Target cell
Target cell
Circulatory vessel
(e.g., a blood vessel)
Target cell
Figure 5.11 Signal Transduction Concepts
Signal
molecule
Receptor
Short-term
responses:
enzyme activation,
cell movement
Inactive
signal
transduction
molecule
Activated
signal
transduction
molecule
Long-term
responses:
altered DNA
transcription
Figure 5.12 A Signal Binds to Its Receptor
Ligand
Outside of cell
Cell membrane
Inside of cell
In-Text Art, Ch. 5, p. 76
Signal
molecule
Receptor
R+L
RL
Figure 5.13 A Protein Kinase Receptor
Signal
(insulin)
Outside of cell
Receptor
Protein
kinase
domain
(inactive)
ATP
ADP
Phosphate
groups
Target
Cellular
responses
Inside of cell
Figure 5.14 A G Protein–Linked Receptor (Part 1)
Outside of cell
Signal (hormone)
GDP
G proteinlinked
receptor
Inside of cell
Inactive
G protein
Inactive effector
protein
Figure 5.14 A G Protein–Linked Receptor (Part 2)
Outside of cell
GTP
Activated
G protein
Inside of cell
Figure 5.14 A G Protein–Linked Receptor (Part 3)
Outside of cell
Activated
effector protein
GDP
Reactant
Inside of cell
Product
Amplification
Figure 5.15 The Discovery of a Second Messenger (Part 1)
A second messenger mediates between receptor activation at
the plasma membrane and enzyme activation in the cytoplasm.
Cytoplasm
contains
inactive
glycogen
phosphorylase
Liver
Membranes
contain
epinephrine
receptors
Figure 5.15 The Discovery of a Second Messenger (Part 2)
A second messenger mediates between receptor activation at
the plasma membrane and enzyme activation in the cytoplasm.
Active glycogen phosphorylase is present in the cytoplasm.
A soluble second messenger, produced by hormone-activated
membranes, is present in the solution and activates enzymes in
the cytoplasm.
The activity of previously inactive liver glycogen
phosphorylase was measured with and without
epinephrine incubation, with these results:
Condition
Enzyme activity (units)
Homogenate
Homogenate + epinephrine
Cytoplasm fraction
Cytoplasm + epinephrine
Cytoplasm + membranes
Cytoplasm + membranes + epinephrine
0.4
2.5
0.2
0.4
0.4
2.0
A. What do these data show?
B. Propose an experiment to show that the factor that
activates the enzyme is stable on heating and give
predicted data.
C. Propose an experiment to show that cAMP can
replace the particulate fraction and hormone treatment
and give predicted data.
Figure 5.16 The Formation of Cyclic AMP (Part 1)
Adenylyl
cyclase
ATP
cAMP +
PPi
Figure 5.16 The Formation of Cyclic AMP (Part 2)
Adenine
Phosphate groups
ATP
Figure 5.16 The Formation of Cyclic AMP (Part 3)
Cyclic AMP (cAMP)
Figure 5.17 A Cascade of Reactions Leads to Altered Enzyme Activity (Part 1)
1
Epinephrine
Outside of cell
Activated
G protein
subunit
Epinephrine
receptor
Plasma
membrane
Activated
adenylyl
cyclase
GTP
ATP
cAMP
20
Inactive protein kinase A
20
Active protein kinase A
Inactive phosphorylase kinase
100
Active glycogen
synthase
Inactive glycogen
synthase
Active phosphorylase kinase
Figure 5.17 A Cascade of Reactions Leads to Altered Enzyme Activity (Part 2)
100
Active phosphorylase kinase
Inactive glycogen phosphorylase
1,000
Active glycogen phosphorylase
Glycogen
10,000
Glucose 1-phosphate
Glucose
Inside of cell
10,000
Outside of cell
Blood glucose
Figure 5.18 Signal Transduction Regulatory Mechanisms (Part 1)
ATP
Protein kinase
P
Inactive
enzyme
Active
enzyme
Pi
Protein
phosphatase
Figure 5.18 Signal Transduction Regulatory Mechanisms (Part 2)
Receptor binding
Inactive
G protein
GTP
GDP
GTPase
Active
G protein
Figure 5.18 Signal Transduction Regulatory Mechanisms (Part 3)
Adenylyl
cyclase
ATP
Phosphodiesterase
cAMP
AMP
Figure 5.19 Caffeine and the Cell Membrane (Part 1)
Outside
of cell
Plasma
membrane
Inside
of cell
Figure 5.19 Caffeine and the Cell Membrane (Part 2)
Caffeine
Adenosine