BIOC 384 Exam 3 Review 2026 | Verified Q&A | Graded A+
1. If a drug were to inhibit tumor necrosis factor receptors, what potential
cellular outcome could be expected?
Reduced inflammatory response
Enhanced DNA replication
Increased protein synthesis
Accelerated cell division
2. Enterokinase activates which pancreatic zymogen?
chymotrypsinogen
pepsinogen
procarboxypeptiase
trypsinogen
3. Describe the relationship between phosphodiesterase inhibition by caffeine
and cAMP levels in cells.
Phosphodiesterase inhibition by caffeine decreases cAMP levels.
Caffeine decreases cAMP levels by activating phosphodiesterase.
Inhibition of phosphodiesterase by caffeine leads to increased
cAMP levels in cells.
Caffeine has no impact on cAMP levels in cells.
4. Describe the significance of the heterotrimeric G protein binding site in the
context of ligand binding and structural changes.
, The heterotrimeric G protein binding site remains unchanged during
ligand binding.
The heterotrimeric G protein binding site undergoes significant
structural changes that facilitate signal transduction upon ligand
binding.
The heterotrimeric G protein binding site only binds cAMP without
structural changes.
The heterotrimeric G protein binding site is primarily involved in DNA
binding.
5. The is equal to the rate of synthesis minus the rate of breakdown of the
metabolite.
metabolic rate
Keq
endergonicity
flux
none of the above
6. Describe the role of procaspase 8 in the apoptosis signaling pathway.
Procaspase 8 directly activates procaspase 3 without any cleavage.
Procaspase 8 binds to p65 to initiate signaling pathways unrelated to
apoptosis.
Procaspase 8 is phosphorylated to become active and then cleaves
procaspase 3.
Procaspase 8 is activated by auto-cleavage and initiates the
caspase cascade leading to apoptosis.
,7. What prevents hydrated Na+ and K+ ions from passing through the nicotinic
acetylcholine receptor channel in the absence of acetylcholine?
A ring of nonpolar amino acids in the interior chamber prevents the
hydrated ions from moving through the constricted channel.
The nicotinic acetylcholine receptor is a G protein-coupled receptor
that blocks Na+ and K+ channel by association with a heterotrimeric G
protein.
A ring of positively-charged amino acids in the upper and lower outer
chambers prevents the hydrated ions from entering the channel.
The diameter of the hydrated Na+ and K+ ions is too large to fit
through the inner and outer chambers and they never reach the inner
chamber.
8. What is the role of cAMP in the activation of protein kinase A (PKA)?
cAMP binds to the catalytic subunit of PKA, promoting association of
the pseudosubstrate and activating it.
cAMP acts as a source of energy for PKA's catalytic reaction.
cAMP binds to the regulatory subunit of PKA, promoting its
dissociation from the catalytic subunit and activating it.
cAMP binds to the active site of PKA, promoting its association with its
substrates.
9. Glucagon is a hormone that activates receptors
Amino-acid derivative; tyrosine kinase
Protein; nuclear
Protein; G-protein coupled
Protein; tyrosine kinase
, 10. Describe the significance of the amino acid composition at the termini of
pepsin in relation to its function.
The charged amino acids at the N-terminus enhance the enzyme's
catalytic activity, while the nonpolar amino acids at the C-terminus
stabilize the enzyme.
The nonpolar amino acids at the N-terminus contribute to the
stability and folding of the enzyme, while the polar amino acid at
the C-terminus may play a role in interactions with substrates.
The amino acids at the termini have no significant impact on the
enzyme's function.
The polar amino acids at both termini allow for better solubility in
aqueous environments.
11. If a mutation occurs in a protein that prevents it from binding to PIP3, what
potential effect could this have on cellular signaling?
Increased activation of all signaling pathways in the cell.
Disruption of signaling pathways that rely on PIP3 for activation.
No effect on cellular signaling as PIP3 is not essential.
Enhanced binding of other ligands to the protein.
12. Describe how receptor tyrosine kinases initiate a signaling cascade upon
activation.
Receptor tyrosine kinases directly activate transcription factors in the
nucleus.
Receptor tyrosine kinases bind to G-proteins, activating them to
initiate signaling.
Receptor tyrosine kinases dimerize and autophosphorylate,
leading to the recruitment of signaling proteins.
1. If a drug were to inhibit tumor necrosis factor receptors, what potential
cellular outcome could be expected?
Reduced inflammatory response
Enhanced DNA replication
Increased protein synthesis
Accelerated cell division
2. Enterokinase activates which pancreatic zymogen?
chymotrypsinogen
pepsinogen
procarboxypeptiase
trypsinogen
3. Describe the relationship between phosphodiesterase inhibition by caffeine
and cAMP levels in cells.
Phosphodiesterase inhibition by caffeine decreases cAMP levels.
Caffeine decreases cAMP levels by activating phosphodiesterase.
Inhibition of phosphodiesterase by caffeine leads to increased
cAMP levels in cells.
Caffeine has no impact on cAMP levels in cells.
4. Describe the significance of the heterotrimeric G protein binding site in the
context of ligand binding and structural changes.
, The heterotrimeric G protein binding site remains unchanged during
ligand binding.
The heterotrimeric G protein binding site undergoes significant
structural changes that facilitate signal transduction upon ligand
binding.
The heterotrimeric G protein binding site only binds cAMP without
structural changes.
The heterotrimeric G protein binding site is primarily involved in DNA
binding.
5. The is equal to the rate of synthesis minus the rate of breakdown of the
metabolite.
metabolic rate
Keq
endergonicity
flux
none of the above
6. Describe the role of procaspase 8 in the apoptosis signaling pathway.
Procaspase 8 directly activates procaspase 3 without any cleavage.
Procaspase 8 binds to p65 to initiate signaling pathways unrelated to
apoptosis.
Procaspase 8 is phosphorylated to become active and then cleaves
procaspase 3.
Procaspase 8 is activated by auto-cleavage and initiates the
caspase cascade leading to apoptosis.
,7. What prevents hydrated Na+ and K+ ions from passing through the nicotinic
acetylcholine receptor channel in the absence of acetylcholine?
A ring of nonpolar amino acids in the interior chamber prevents the
hydrated ions from moving through the constricted channel.
The nicotinic acetylcholine receptor is a G protein-coupled receptor
that blocks Na+ and K+ channel by association with a heterotrimeric G
protein.
A ring of positively-charged amino acids in the upper and lower outer
chambers prevents the hydrated ions from entering the channel.
The diameter of the hydrated Na+ and K+ ions is too large to fit
through the inner and outer chambers and they never reach the inner
chamber.
8. What is the role of cAMP in the activation of protein kinase A (PKA)?
cAMP binds to the catalytic subunit of PKA, promoting association of
the pseudosubstrate and activating it.
cAMP acts as a source of energy for PKA's catalytic reaction.
cAMP binds to the regulatory subunit of PKA, promoting its
dissociation from the catalytic subunit and activating it.
cAMP binds to the active site of PKA, promoting its association with its
substrates.
9. Glucagon is a hormone that activates receptors
Amino-acid derivative; tyrosine kinase
Protein; nuclear
Protein; G-protein coupled
Protein; tyrosine kinase
, 10. Describe the significance of the amino acid composition at the termini of
pepsin in relation to its function.
The charged amino acids at the N-terminus enhance the enzyme's
catalytic activity, while the nonpolar amino acids at the C-terminus
stabilize the enzyme.
The nonpolar amino acids at the N-terminus contribute to the
stability and folding of the enzyme, while the polar amino acid at
the C-terminus may play a role in interactions with substrates.
The amino acids at the termini have no significant impact on the
enzyme's function.
The polar amino acids at both termini allow for better solubility in
aqueous environments.
11. If a mutation occurs in a protein that prevents it from binding to PIP3, what
potential effect could this have on cellular signaling?
Increased activation of all signaling pathways in the cell.
Disruption of signaling pathways that rely on PIP3 for activation.
No effect on cellular signaling as PIP3 is not essential.
Enhanced binding of other ligands to the protein.
12. Describe how receptor tyrosine kinases initiate a signaling cascade upon
activation.
Receptor tyrosine kinases directly activate transcription factors in the
nucleus.
Receptor tyrosine kinases bind to G-proteins, activating them to
initiate signaling.
Receptor tyrosine kinases dimerize and autophosphorylate,
leading to the recruitment of signaling proteins.
