Cell Biology

“When cobra venom is introduced into the body it moves along the bloodstream to the
diaphragm muscle. It works as a postsynaptic neurotoxin binding to the receptor as an
extracellular ligand by interacting with OH group leaving the acetyl choline channel open
which releases ions used in creating an action potential.”
https://proteopedia.org/wiki/index.php/Acetylcholine_Receptor_and_its_Reaction_to_Cobra_Venom#:~:text
=When%20cobra%20venom%20is%20introduced,in%20creating%20an%20action%20potential.
Just based on the description above, diagram an experiment that would show this is how
the specific venom / receptor interaction is happening. You need to use a specific patch
clamp technique. Along with your drawing, explain which specific technique you chose
and why. Explain how the experiment would work – for example where would you put the
cobra venom). Explain, what would be the result, at the cellular level the muscle cell was
exposed to this venom.
2. Draw an action potential graph showing the effects of the venom on an action potential
(draw a normal action potential and then draw the effect with the venom present). You
are drawing two sequential / consecutive action potentials, like the diagram below, but
showing the effects of the venom. So, you have 2 sequential action potentials, a normal
one and then immediately what is happening with cobra venom. This allows me to see
how you think the action potential will be different with the venom. Also, explain in
words what is happening in your graph.
3. Why does cobra venom lead to trouble breathing and death? (Look this up and cite your
references).
4. Drugs that affect the reuptake of neurotransmitters are in widespread use for the
treatment of attention-deficit/hyperactivity disorder and clinical depression. In molecular
terms, explain what effect(s) such reuptake inhibitors have on postsynaptic neurons if
the neurotransmitter in question is excitatory for that postsynaptic neuron. In your
answer include what would happen to the postsynaptic neuron with and without
the reuptake inhibitors. Also, include the concept of summation (and be specific as to
what type of summation would happen in the presence of the reuptake inhibitors).
5. Draw three consecutive action potentials (as in question 2). The first is a normal
action potential, the second is an action potential when a reuptake inhibitor is present,
and the third is an action potential when a reuptake inhibitor is absent. Explain what why
these action potentials are different. Include the concept of EPSPs.
6. Based on the following description, draw the cell signaling pathway described (you
only need to draw the pathway in one cell, but show the type of signaling described).
Label all your parts. Circle the signal transduction pathway and put a box around the
cell response. What type of signaling is this?
Compound X is released from one cell and activates not only itself, but its neighboring
cells. Compound X binds its receptor and some of the serine amino acids on the
cytoplasmic side of the receptor are phosphorylated. Label what type of receptor this
is. This leads to the receptor phosphorylating a cytoplasmic protein (figure out and label
what type of protein this is). There is a scaffolding protein that organizes the 4 other
this is an example of two
sequential / consecutive
normal action potentials
proteins involved in signal transduction. Eventually, several genes are turned on for
transcription / expression.
7. Compare and contrast the concepts of cross-talk and signal amplification in cell
signaling pathways.
8. Given the following cell signaling pathway, what does each box represent? These are
all terms from chapter 23. For your answer, just list the letter and the term.
A and B are receptor types. The rest are signaling molecules / proteins.
9. You are trying to understand the insulin signaling pathway (see pathway in your text or in the
posted PDF for chapter 23). You are looking to show protein: protein interactions (these can
be the ligand, receptor and/or signaling protein interactions).
Use any of the techniques listed below to study the given pathway. You need to explain
which technique you are using and which protein you are targeting (you must target 3
specific different proteins) and why (for both the technique and the protein choice). Next
explain how your technique will allow you to study the pathway; in other words what will
happen when the pathway is disrupted, how will you know the role of your target protein?
Technique choices:
• Dominant-negative mutant
• Temperature-sensitive mutant
• Antibodies
• Non-degradable forms of a protein
• non-hydrolyzable ATP
A B
C
D E
F
G
H
10.You are studying the cell cycle. For the conditions below state what will be inhibited in
each scenario. BE SPECIFIC. Also state which could lead to cancer and why.
a. CEN sequences are mutated
b. astral motor proteins cannot hydrolyze ATP
c. cohesion is not broken down
d. cyclin B cannot bind its Cdk
e. Cdc20 does not leave the centromere
f. securin is missing
g. the phosphatase for Rb does not function
h. MdM2 is permanently bound to p53
i. PI3K cannot phosphorylate Akt
j. geminin is in active
11.There are six hallmarks of cancer listed below. State which would be associated with an
oncogene or with a tumor suppressor mutation or neither or both. Explain your answer.
1. self-sufficiency in growth signals
2. insensitivity to antigrowth signals
3. evasion of apoptosis
4. limitless replicative potential
5. sustained angiogenesis
6. tissue invasion and metastasis