Question

1. View the side groups in the model, with attention to the water channel. What do the numerous aromatic rings on the surface of the channel suggest about the chemical properties of the channel?

The channel will have a net negative charge.

The channel will have significant hydrophobic properties.

The channel will have significant hydrophilic properties.

The channel will have a net positive charge.

2. Conserved histidine, asparagine (blue), and cysteine (yellow) residues are present on the surface of the water channel. Which of the following is LEAST likely to hydrogen-bond with a water molecule?

the R group (side chain) of the cysteine

the R groups (side chains) of the two asparagines

the backbone carbonyl groups of amino acids on the surface of the channel

the R group (side chain) of a histidine

3. What prevents glycerol from passing through the water channel?

the backbone carbonyl groups of amino acids in the channel

the chemical properties of the cysteine in the channel

the chemical properties of the two conserved asparagines in the channel

the narrow diameter (~2.8 Å) of the selectivity channel

4. Aquaporins allow water to pass through the channel but prevent other solutes and ions from also crossing the membrane. Protons can move with water using the same hydrogen bonding facillitated movement. What PREVENTS protons from passing through the water channel?

the backbone carbonyl oxygen groups of amino acids in the channel

the chemical properties of the amine groups of the two conserved asparagines in the channel

the narrow diameter (~2.8 Å) of the selectivity channel

the chemical properties of the sulfur within the R group of the conserved cysteine in the channel

Answer 1