Binding of a signaling molecule to which type of receptor leads directly to a change in the distribution of substances on opposite sides of the membrane? a. intracellular receptor b. G protein-coupled receptor c. phosphorylated receptor tyrosine kinase dimer d. ligand-gated ion channel

Verified step by step guidance

1. Identify the type of receptors listed and understand their basic functions. Intracellular receptors typically bind to molecules that can cross the cell membrane and affect transcription directly. G protein-coupled receptors activate internal signaling pathways. Receptor tyrosine kinases, when phosphorylated, also initiate several signaling cascades.
2. Focus on the receptor that directly changes the distribution of ions or molecules across the membrane. This process usually involves the movement of substances into or out of the cell.
3. Consider the mechanism of a ligand-gated ion channel, which opens in response to the binding of a signaling molecule, allowing specific ions to flow through the membrane, thereby changing the ion concentration on either side of the membrane.
4. Compare this mechanism to the other options. Intracellular receptors and receptor tyrosine kinases influence gene expression and enzyme activation, respectively, rather than directly altering substance distribution across the membrane. G protein-coupled receptors indirectly influence cellular changes through secondary messengers rather than directly changing ion distribution.
5. Conclude that the correct answer is 'd. ligand-gated ion channel' because this type of receptor directly leads to a change in the distribution of substances across the membrane by allowing ions to pass through the membrane when the receptor is activated by a ligand.