Question

Which of the following hormone categories requires G protein to activate enzymes inside a cell

Option 1: Steroid hormones
Option 2: Peptide hormones
Option 3: Thyroid hormones
Option 4: Amino acid-derived hormones

Answer 1

Peptide hormones require a G protein to activate enzymes inside a cell. They bind to cell surface receptors, activate G proteins, and trigger signaling pathways using cAMP as a second messenger, which results in cellular responses.

Step-by-step explanation:

The category of hormones that requires a G protein to activate enzymes inside a cell is peptide hormones. Unlike steroid or thyroid hormones, peptide hormones are not lipid-soluble and thus they cannot pass directly through the cell membrane.

Instead, they bind to receptors on the surface of the cell and activate an intracellular signaling pathway.

The binding of a peptide hormone, such as epinephrine or glucagon, to its receptor activates a G protein, which in turn activates an enzyme called adenylyl cyclase, leading to the production of cyclic adenosine monophosphate (cAMP) as a second messenger. This second messenger then activates a cascade of protein kinases, leading to various cellular responses.