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Signal transduction, the propagation of a signal through the cytoplasm after receptor binding, only occurs with one class of receptor. Which class, and why?

AInternal receptors, because they never leave the cytoplasm
BBoth internal and cell-surface receptors equally, since both trigger cascades
CCell-surface receptors, because internal receptors act directly on DNA in the nucleus
DEnzyme-linked receptors only, because other cell-surface receptors lack a cascade
Answer & Solution
Correct answer: C. Cell-surface receptors, because internal receptors act directly on DNA in the nucleus
1. Signal transduction is the continuation of a signal through the membrane and into the cytoplasm after a ligand binds a receptor. 2. This process only occurs with cell-surface receptors. 3. Internal receptors instead interact directly with DNA in the nucleus to initiate protein synthesis, so they do not need a cytoplasmic cascade. 4. Because internal receptors bypass the cytoplasm entirely, the option claiming both receptor types use signal transduction equally is incorrect. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 9 "Cell Communication", section 9.2 | Propagation of the Signal_
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