Question

A researcher has discovered a new ligand that can pass through the cell membrane and bind to a receptor in the nucleus. Which of the following statements is not likely true of this ligand?

Please choose the correct answer from the following choices, and then select the submit answer button.


-This ligand likely plays a role in transcription.

-This ligand likely has a similar structure to cholesterol.

-This ligand likely binds to a transmembrane receptor.

-This ligand is likely a steroid.

-This ligand is likely nonpolar.

Answer 1

The statement least likely to be true is that the ligand binds to a transmembrane receptor, as the ligand's ability to enter the cell and bind to a nuclear receptor suggests it is nonpolar and similar in behavior to steroids, not requiring a surface receptor to mediate its effects.

Step-by-step explanation:

The statement that is not likely true about the new ligand discovered by the researcher is "This ligand likely binds to a transmembrane receptor." This is due to the fact that the ligand is able to pass through the cell membrane and bind to a receptor in the nucleus, suggesting that it is likely nonpolar and could be similar to a steroid, which is known to pass through cell membranes easily and bind to internal receptors.

Internal receptors tend to be activated by hydrophobic, or nonpolar, ligands that can diffuse through the lipid bilayer of the cell membrane. This internal binding often results in the ligand-receptor complex influencing gene expression by interacting directly with DNA in the nucleus, thus playing a role in transcription. On the other hand, hydrophilic ligands, which are water-soluble, generally cannot penetrate the cell membrane, so they bind to cell-surface receptors and initiate signaling cascades internally without entering the cell nucleus, employing second messengers to relay their signal.