Receptors for signal molecules are typically located where in the cell?

• A. Embedded in the Golgi apparatus
• B. On the cell surface membrane
• C. Inside the nucleus
• D. Within the mitochondria

Answer: (B)

Verified step by step guidance

1. Understand the role of receptors: Receptors are proteins that bind to specific signal molecules (ligands) to initiate a cellular response. Their location depends on the type of signal molecule they interact with.
2. Analyze the nature of signal molecules: Signal molecules can be hydrophilic (water-soluble) or hydrophobic (lipid-soluble). Hydrophilic molecules cannot pass through the lipid bilayer of the cell membrane, so their receptors are typically located on the cell surface.
3. Consider the cell surface membrane: The cell surface membrane (plasma membrane) is the primary location for receptors that interact with hydrophilic signal molecules, such as hormones or neurotransmitters, because these molecules cannot diffuse through the membrane.
4. Evaluate the other options: Receptors are not typically embedded in the Golgi apparatus, as the Golgi is involved in protein modification and trafficking. Similarly, receptors inside the nucleus or mitochondria are usually for hydrophobic molecules like steroid hormones, which can diffuse through the membrane.
5. Conclude that the correct location for most receptors interacting with hydrophilic signal molecules is on the cell surface membrane, as this allows them to detect extracellular signals and transmit them into the cell.