Using patch-clamp technique, one can find the ligands that could influence specific ion channels. How many molecules of acetylcholine are required to open an acetylcholine receptor ion channel in such an experiment?

Correct option is B

Explanation:

For the acetylcholine receptor (AChR) to open, two acetylcholine molecules are required to bind to two of the four subunits of the receptor. The AChR is a pentameric structure with five subunits (two alpha, one beta, one gamma, and one delta). Acetylcholine binding to the two alpha subunits results in the opening of the ion channel, allowing the passage of ions.

Information Booster:

1. The acetylcholine receptor is a pentameric ion channel, and it consists of five subunits. However, only the two alpha subunits require the binding of acetylcholine for the ion channel to open.

2. Upon binding of acetylcholine to the alpha subunits, a conformational change occurs in the receptor, which leads to the opening of the ion channel.

3. Once the channel opens, sodium (Na⁺) and potassium (K⁺) ions can flow across the membrane, resulting in changes in membrane potential.

4. The patch-clamp technique allows precise measurement of ion channel activity by isolating and analyzing the current through individual ion channels.

5. AChRs play a vital role in synaptic transmission and are particularly important in neuromuscular junctions and central nervous system synapses.

Additional Knowledge:

• One acetylcholine molecule (option 1) would not be sufficient to open the receptor because both alpha subunits need to be bound for activation.

• Three acetylcholine molecules (option 3) are also insufficient, as only two molecules bind to the receptor for opening.

• Four acetylcholine molecules (option 4) are excessive because the receptor only needs two molecules to initiate the channel opening.