Final answer:
The charge of amino acids in the ion channel's pore is pivotal for ion selectivity. Positively charged amino acids attract negatively charged ions, while negatively charged amino acids attract positively charged ions, facilitating the passage of specific ions based on charge, a concept known as electrochemical exclusion.
Step-by-step explanation:
The charge of amino acids that line the inside of an ion channel's pore plays a significant role in determining which ions can pass through due to electrostatic interactions. Specifically, positively charged amino acids attract negatively charged ions, making them conductive to anions. Conversely, negatively charged amino acids attract positively charged ions, which allows the passage of cations through the channel. This selective process is known as electrochemical exclusion, where the channel's pore is charge-specific. Additionally, the concept of size exclusion means that the diameter of the pore is specific to the size of the ion, allowing for selective permeability not only based on charge but also on the ion's size, especially when it dissociates from its hydrating water molecules.
Therefore, the most accurate responses to the student's question are:
- Option 1: Positively charged amino acids attract negatively charged ions.
- Option 2: Negatively charged amino acids attract positively charged ions.
Options 3 and 4 are incorrect as neutral amino acids do not repel all ions, and the charges most definitely have an effect on ion passage.