, 1. Which of the following molecules is a second
messenger?
a) ATP
b) Insulin
c) cAMP
d) DNA
Answer: c) cAMP
Rationale: Cyclic AMP (cAMP) is a second messenger
used for intracellular signal transduction in many biological
processes.
2. Protein kinases are crucial in signaling pathways
because they:
a) Directly activate genes
b) Hydrolyze phospholipids
c) Phosphorylate proteins
d) Degrade proteins
Answer: c) Phosphorylate proteins
Rationale: Protein kinases add phosphate groups to
proteins, often activating or deactivating them, which is vital
for signal transduction.
4. What is the role of phosphatases in cell signaling?
a) Phosphorylate substrates
b) Deactivate cAMP
c) Remove phosphate groups
d) Bind to receptors
Answer: c) Remove phosphate groups
Rationale: Phosphatases remove phosphate groups,
counteracting the action of kinases.
5. Which molecule can act both as a neurotransmitter
and a hormone?
a) Acetylcholine
b) Dopamine
c) Noradrenaline
d) Histamine
Answer: c) Noradrenaline
Rationale: Noradrenaline functions as a neurotransmitter in
the nervous system and as a hormone in the bloodstream.
6. In the context of cell signaling, what is apoptosis?
a) Cell division
b) Programmed cell death
c) Uncontrolled cell growth
d) Cellular differentiation
Answer: b) Programmed cell death
Rationale: Apoptosis is a process of programmed cell
death, which is often regulated by signaling pathways.
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