1. Kinesin is a molecular "motor" that interacts with
a. cell membranes
b.. myosin thick filaments
c. actin microfilaments
d. microtubules
e. intermediate filaments
2. Which of the following would not affect the permeability (P) of a solute in a membrane?
a. concentration gradient of that
solute
b. diffusion coeficient, Dm
c. thickness of membrane
d. transporter proteins in the membrane
for that solute
e. oil/water partition coeficient
3. An ion channel . . .
a. may display saturation kinetics
b. always conducts inward current
c. is represented as a capacitor
in membrane equivalent circuits
d. requires an ion to have a high
oil/water partition coeficient in order to be conducted through the channel
e. all of the above
Questions 4 and 5 refer to the figure below, which represents a current recording from a voltage-clamped cell during an action potential.
4. Which letter corresponds to the rising phase (depolarization) of the action potential?
5. Which letter corresponds to a peak in K+ conductance?
6. Which of the following is not true regarding an action potential?
a. membrane PD approaches ENa+
b. Na+ conductance transiently exceeds
K+ conductance
c. is an example of a positive feedback
system
d. rising phase corresponds to an
early outward current of K+
e. initiated when a certain critical
threshold of depolarization is reached
7. Which of the following is incorrect ?
a. an action potential can propagate
along an axon with no loss of amplitude
b. myelinated axons have higher
conduction velocities than non-myelinated axons
c. propagation of an action potential
requires voltage-gated Ca++ channels at each "patch"
d. propagation of an action potential
is a regenerative process, dependent on local currents flowing ahead of
the active patch
e. propagation of an action potential
proceeds in one direction because of the refractoriness of previously excited
patches
8. The reduction in action potential amplitude, seen during the relative refractory period, can be attributed to
a. decreased activity of the Na+/K+
ATPase
b. residual K+ channel conductance
c. decreased emf for Na+
d. decreased intracellular calcium
concentration
e. all of the above
9. An EPSP is generated by the opening of voltage-gated Na+ channels.
a. True
b. False
10. An IPSP is characterized by . . .
a. net inward current
b. net outward current
c. no net current
11. Summation at a post-synaptic nerve cell
a. can involve both excitatory and
inhibitory inputs
b. is required for generation of
a post-synaptic action potential
c. may occur in response to multiple
action potentials from a single pre- synaptic cell
d. depends on passive, electrotonic
spread of current from the dendritic area
e. all of the above
12. An example of an amino acid that typically acts as a neurotransmitter at inhibitory synapses is
a. epinephrine
b. dopamine
c. acetylcholine
d. GABA
e. curare
13. Which of the following does not occur during an isotonic muscle contraction?
a. I band shortens
b. H zone decreases
c. A band shortens
d. sarcomere shortens
e. z lines move closer
14. In the cross bridge cycle myosin head groups that have bound, unhydrolyzed ATP have high actin affinity.
a. True
b. False
15. In skeletal muscle cells, ATP
is required for. . .
a. crossbridge cycle
b. sarcoplasmic reticulum uptake
of Ca++
c. maintenance of low intracellular
Na+ concentration
d. a and b
e. a, b and c
16. Cellular proteins are sorted
and targeted for specific destinations by the...
17. In the nervous system, the strength
of a stimulus is coded by...
18. The combined electrical and chemical
driving forces, acting on an ion, are called the...
19. What is responsible for the
spontaneous termination of the early inward current, as seen in voltage
clamp experiments on neurons?
20. The site in nerve cells where action potentials are typically initiated is...
21. What is responsible for the rapid termination of acetylcholine-induced EPPs (EPSPs) at the neuromuscular junction?
22. The process whereby a pre-synaptic cell can modulate the excitatory influence of another pre-synaptic cell on a post-synaptic cell is called...
23. A class of neuropeptides that act in the central nervous system to reduce the sensation of pain is...
24. Sensory nerve cell bodies of the spinal nerves are found in the...
25. The calcium-binding protein complex found in muscle cell thin filaments is...
26. List two important roles
of tight junctions in epithelia. (4 pts)
27. List three factors that affect membrane fluidity (5 pts)
28. Assume that a cell, under resting conditions, has essentially zero permeability to all ions except lithium (Li+). Further assume that the intracellular and extracellular concentrations of Li+ are 0.5 mM/L and 5.0 mM/L, respectively. Show how you would predict the cell membrane resting PD at equilibrium (ie, set up equation). Will the PD be positive or negative ? (6 pts)
29. Describe (in words or drawings) the channel states (ie gate positions) for both Na+ and K+ channels during the absolute refractory period. (5 pts)
30. Draw the structure of a chemical synapse as exemplified by the neuromuscular junction. Label all important features. (7 pts)
31. Describe, briefly, the experimental approach that was used to demonstrate the existance and nature of end plate potentials (EPPs or muscle EPSPs) at the frog neuromuscular junction. (6 pts)
32. List the important features of the acetylcholine receptor channel of the neuromuscular junction. (5 pts).
33. Describe, briefly, two different calcium-dependent processes that play a role in the function of nerve and muscle cells. How are each of these calcium-dependent events mediated? (6 pts)
34. List the sequence of events
during excitation-contraction coupling in muscle. (6 pts)