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Multiple Choice
Which of the following molecules are commonly used as second messengers in signal transduction pathways?
A
Insulin
B
Phospholipid bilayer
C
Cyclic AMP (cAMP)
D
DNA polymerase
Verified step by step guidance
1
Step 1: Understand the concept of second messengers. Second messengers are molecules that relay signals received at receptors on the cell surface to target molecules inside the cell, amplifying the signal in signal transduction pathways.
Step 2: Identify the characteristics of second messengers. They are typically small, non-protein molecules or ions that can rapidly diffuse within the cell. Examples include cyclic AMP (cAMP), calcium ions (Ca²⁺), and inositol triphosphate (IP₃).
Step 3: Analyze the options provided in the question. Insulin is a protein hormone, not a second messenger. The phospholipid bilayer is a structural component of the cell membrane, not a signaling molecule. DNA polymerase is an enzyme involved in DNA replication, not signal transduction.
Step 4: Recognize that cyclic AMP (cAMP) is a well-known second messenger. It is synthesized from ATP by the enzyme adenylyl cyclase and plays a key role in transmitting signals from cell surface receptors to intracellular targets.
Step 5: Conclude that cyclic AMP (cAMP) is the correct answer based on its role as a second messenger in signal transduction pathways, while the other options do not fit the criteria for second messengers.