AP BIOLOGY

Detailed explanation-1: -Steroid hormones and thyroid hormone are lipid soluble. All other amino acid–derived hormones are water soluble. Hydrophobic hormones are able to diffuse through the membrane and interact with an intracellular receptor. In contrast, hydrophilic hormones must interact with cell membrane receptors.

Detailed explanation-2: -There are two classes of hormone receptors: those bound to the membrane and those present in the cytosol. Peptide hormones generally act through membrane receptors. The interaction of a hormone with its receptors leads to an activation of the adenylate cyclase and the production of cyclo-AMP, the second messenger.

Detailed explanation-3: -Receptors for peptide hormones tend to be found on the plasma membrane of cells, whereas receptors for lipid-soluble hormones are usually found within the cytoplasm.

Detailed explanation-4: -The water-soluble hormone receptors are only found on the cell surface because these proteins receive the message and direct the cells to perform their function.

Detailed explanation-5: -Lipid insoluble hormones bind to receptors on the outer surface of the plasma membrane, via plasma membrane hormone receptors. Unlike steroid hormones, lipid insoluble hormones do not directly affect the target cell because they cannot enter the cell and act directly on DNA.