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Multiple Choice
Which of the following signaling pathways would be likely to trigger the most rapid cell response?
A
G protein-coupled receptor (GPCR) signaling
B
Ligand-gated ion channel signaling
C
Receptor tyrosine kinase (RTK) signaling
D
Steroid hormone receptor signaling
Verified step by step guidance
1
Understand the nature of each signaling pathway: Ligand-gated ion channel signaling involves the direct opening of ion channels upon ligand binding, leading to immediate changes in ion concentrations across the membrane. G protein-coupled receptor (GPCR) signaling involves a cascade of intracellular events, which can take longer. Receptor tyrosine kinase (RTK) signaling involves phosphorylation and downstream signaling cascades, which are also relatively slower. Steroid hormone receptor signaling involves changes in gene expression, which is the slowest of all.
Recognize that the speed of a signaling pathway is determined by how directly it affects cellular processes. Ligand-gated ion channel signaling directly alters ion flow across the membrane, which can immediately affect the cell's electrical state or ion-dependent processes.
Compare the mechanisms: GPCR signaling, RTK signaling, and steroid hormone receptor signaling all involve multiple steps, such as second messenger production, phosphorylation cascades, or transcriptional changes, which inherently take more time.
Focus on the ligand-gated ion channel signaling pathway: Since it directly opens ion channels upon ligand binding, it bypasses complex intracellular signaling cascades, making it the fastest in triggering a cell response.
Conclude that ligand-gated ion channel signaling is likely to trigger the most rapid cell response due to its direct mechanism of action, compared to the other pathways that involve slower, multi-step processes.