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

The channel will have a netnegative charge.

The channel will havesignificant hydrophobic properties.

The channel will havesignificant hydrophilic properties.

The channel will have a netpositive charge.

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

the R group (side chain) ofthe cysteine

the R groups (side chains) ofthe two asparagines

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

the R group (side chain) of ahistidine

3. What prevents glycerol from passing through the waterchannel?

the backbone carbonyl groupsof amino acids in the channel

the chemical properties of thecysteine in the channel

the chemical properties of thetwo conserved asparagines in the channel

the narrow diameter (~2.8 Ã…)of the selectivity channel

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

the backbone carbonyl oxygengroups of amino acids in the channel

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

the narrow diameter (~2.8 Ã…)of the selectivity channel

the chemical properties of thesulfur within the R group of the conserved cysteine in thechannel