Cell-specific responses to signaling molecules are possible because
A) nuclear receptor expression is cell specific.
B) target palindromic DNA sequences are ubiquitous.
C) signaling molecules are hydrophobic and can pass through the plasma membrane.
D) only some cells express gated channels for the signaling molecules.

Question

Quizplus · Accepted Answer

Cell-specific responses to signaling molecules are possible because nuclear receptor expression is cell-specific, meaning that different cells express different sets of receptors, allowing for specific responses. Hormones, for example, bind to nuclear receptors and activate or inhibit gene transcription, leading to specific cellular responses.

Answer: C 
 Signaling molecules that are hydrophobic, such as steroid hormones or retinoids, can diffuse through the plasma membrane, bind to intracellular receptors, and initiate specific downstream responses. This mode of transmission allows for cell-specific responses, as different cells have different expression levels of receptors for these signaling molecules.

Both A and C are valid choices as they both explain how cell-specific responses to signaling molecules are possible.

Cell-Specific Responses to Signaling Molecules Are Possible Because