Join thousands of students who trust us to help them ace their exams!Watch the first video
Multiple Choice
In the context of cell signaling, which of the following best describes the role of a ligand in signal transduction?
A
A ligand binds to a receptor to initiate a cellular response.
B
A ligand directly synthesizes second messengers inside the cell.
C
A ligand acts as a membrane channel for ions.
D
A ligand degrades signaling proteins to terminate the signal.
Verified step by step guidance
1
Understand the concept of a ligand: A ligand is a molecule that binds specifically to a receptor, typically on the surface of a cell, to initiate a signal transduction pathway. This binding triggers a series of intracellular events leading to a cellular response.
Analyze the role of a receptor: Receptors are proteins that recognize and bind to specific ligands. This interaction is highly specific, much like a lock and key, and is the first step in the signal transduction process.
Evaluate the options provided: The first option states that a ligand binds to a receptor to initiate a cellular response. This aligns with the definition of a ligand's role in signal transduction. The other options describe functions that are not characteristic of ligands.
Clarify why the other options are incorrect: A ligand does not directly synthesize second messengers; instead, the receptor-ligand interaction often activates enzymes or pathways that produce second messengers. A ligand is not a membrane channel for ions; ion channels are separate proteins that may be activated by ligands. Lastly, a ligand does not degrade signaling proteins; this is typically the role of enzymes or other regulatory mechanisms.
Conclude that the correct answer is the first option: A ligand binds to a receptor to initiate a cellular response. This is the fundamental role of a ligand in signal transduction.