 Here
are the Questions submitted by your recitation groups. They are designed
to assist you with your study/review for the final...
Q: Explain the events of how the frequency
of action potentials on the presynaptic neuron determines the magnitude
of the response of the post synaptic structure. This question ensures
that we know what events are going on.
1. Frequency of AP on presynaptic neuron determines
the # & for how long voltage-gated Ca++ channels are open
2. which determines the # of vesicles released
3. which determines the # of vesicles docked at
the presynaptic neuron to yield NT's to synaptic cleft by exocytosis
4. which determines the # of NT's released into
the synaptic cleft
5. which determines the # of receptors occupied
on post synaptic neuron
6. which determines the magnitude of response of
postsynaptic structure
Q: What is the function of MLCK?
A: It regulates smooth muscle activity by phosphorylating
the light chain region of the myosin so that it can bind to actin, which
allows for a contraction of the muscle.
Q: How should the conductance of Na+ or
K+ be changed to increase the heart rate? Explain.
A: Increase gNa+ or decrease gK+; this allows the rate
of spontaneous depolarization to increase.
Q: How should the conductance of Na+ or
K+ be changed to increase the heart rate? Explain.
A: Increase gNa+ or decrease gK+; this allows the rate
of spontaneous depolarization to increase.
Q: As the concentration of Epinephrine
in the blood stream increases what happens to the glycogen concentration
in the liver cells?
Q: Design an experiment to isolate microtubules.
A:
Step 1: Blend cells in an isotonic buffer
to isolate organelles.
Step 2: Put in depolymerization conditions:
cold, high [GDP], low [Mg++], high [Ca++]
Step 3: Centrifuge and remove pellet (which
contains organelles)
Step 4: Put supernatant in polymerization
conditions: heat, high [GTP], high [Mg++], low [Ca++], taxol(drug to stabilize
microtubules)
Q: What are the three problems a cell faces
relating to size?
A:
Surface Area to Volume ratio
Concentration of required substances in intracellular fluid
Q: What is the cyclic cycle in photosynthesis
and why does it occur?
A: The cyclic cycle occurs when NADPH concentration
is high, and the plant undergoes solely ATP synthesis. This occurs
by running photosystem one in a circle, where the electron at the end of
the chain is dumped back onto p700 to go through the cycle again.
Q: What are the properties of simple diffusion?
A:
- down concentration/electrical gradient
- increase in entropy
- no energy required
- works both directions
- diffusion through membrane
- no Vmax or Ka
- no selectivity; no competative inhibition
Q: Describe the structure and function
of RNA polymerase?
A: Five Subunits
- 2a subunits
- 2b subunits
- 1 sigma factor or subunit
It has two functions -
(1) to catalyze the addition of nucleotides
(2) helicase unwinding
Q: What are the two ways of generating
ATP in Cellular Respiration? How much is produced by each?
A:
Substrate-level phosphorylation: 4 ATP
Chemiosmotic Synthesis: 32 ATP
Q: Briefly explain the steps of amino acid
polymerization during mRNA translation beginning with the post-transcriptional
product and ending with the polypeptide. Use diagrams as necessary.
A:
- after post-translational modification,
the 30S subunit binds to mRNA
- the 50S subunit then comes in and
completes the complex, attatching near the start codon (AUG)
- tRNA, which has an anticodon complementary
to the mRNA codon, binds to the appropriate amino acid and brings it to
the A site on the 50S subunit
- tRNA-amino acid complex shifts to the
P site. A new tRNA-amino acid moves into the A site.
- a peptide bond is formed between the
amino acids at the P site
- the first amino acid moves to the E
site and tRNA is released
- a new tRNA-amino acid moves into the
A site and this process continues until a stop codon is reached (UAG, UGA,
UAA)
Q: Explain the makeup of thin filaments.
A: Thin filaments are composed of a strand
of f-actin (from g-actin monomers) with the polypeptides tropomyosin and
troponin (consisting of TnI, TnC, and TnT) intertwined around the actin
strand.
Q: How does epinephrine increase the heart
rate?
A: It binds to an adrenergic receptor on the
heart, which increases the conductance of sodium and decreases the conductance
of pottasium. Therefore, depolarization occurs faster.
Q: Describe the starting and ending materials,
as well as location, of the steps involved in aerobic respiration.
A:
glycolysis-->
Start-6C, 2NAD+, 2ATP
end-2 3C pyruvate, 4ATP(net gain of 2), 2NADH, 2H+
location-cytosol
pyruvate oxidation-->
start-2 3C pyruvate, 2 NAD+, 2 Coash
end-2 CO2, 2 2c Acetyl CoA, 2 NADH, 2H+
location-matrix
citric acid cycle-->
start-2 Acetyl CoA, 2 FAD+, 2NAD+
end-6 NADH, 2FADH2, 4CO2, 2ATP
location-matrix
ETS-->
start-10 NADH, 2 FADH2
end-H2O, 34 ATP, 10 NAD+,2 FAD+, establishes proton
gradient
location-intermembrane to matrix
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