Question

Estrogen and testosterone are steroid hormones and most likely bind to

• A. Membrane ion channels
• B. Enzyme-linked membrane receptors
• C. G-protein-linked membrane receptors
• D. Cytoplasmic receptors

Answer 1

The correct option is D

Cytoplasmic receptors

The correct option is D.

Explanation of the correct option:

1. The group of chemical substances known as steroids includes steroid hormones.
2. The nature of steroid hormones is mostly lipophilic.
3. This is due to the fact that lipids in the cell membrane do not prevent lipophilic substances from entering the cell.
4. Steroid hormones therefore readily permeate through the cell membrane for this reason.
5. The steroid hormones either bind to cytoplasmic or nucleic receptors as they enter the cell.
6. As steroid hormones, estrogen and testosterone are most likely coupled to cytoplasmic receptors.

Explanation of the incorrect options:

Option A:

1. Proteins that allow other ions such as sodium, calcium, potassium, and chloride to pass through the lipid cell membrane, which is normally impermeable to charged ions from dissolved salts.
2. The ion channel is the term used to describe this protein channel.
3. Creating action potentials and other electrical signals by gating the flow of ions across the cell membrane, regulating the flow of ions across secretory and epithelial cells, and establishing the resting membrane potential are just a few of their functions.
4. Ion channels exist in the membranes of all cells.

Option B:

1. Cell-surface receptors with intracellular domains attached to an enzyme are known as enzyme-linked receptors.
2. There are instances when the intracellular domain of the receptor is an enzyme or where the intracellular domain of an enzyme-linked receptor directly interacts with an enzyme.
3. A signal is conveyed across the membrane and activates the enzyme when a ligand attaches to the extracellular domain, starting a chain of events inside the cell that finally leads to a reaction.

Option C:

1. G-proteins, which are membrane proteins, are activated by G-protein-linked receptors once they bind to a ligand.
2. The G-protein then engages in an interaction with an enzyme or ion channel in the membrane.
3. Despite having seven transmembrane domains in common, each G-protein-linked receptor has a different extracellular domain and G-protein binding site
4. G-protein-linked receptors are involved in cycle cell signaling.
5. The dormant G-protein may connect to a recently identified binding site on the receptor before the ligand binds.

Final answer: Estrogen and testosterone are steroid hormones and are most likely bound to cytoplasmic receptors.