Question

The R groups of amino acids located on the surface of protein molecules in the interior of biological membranes are

Answer 1

A. hydrophobic.
B. hydrophilic.
C. polar.
D. able to form disulfide bridges.
E. electrically charged.

Answer 2

i think its B

Answer 3

The reason that the amino acid would have to be hydrophillic is that the hydrophobic regions fold into the center of proteins, to get away from the cytoplasm of the cell, which is mostly water. The R-groups could be polar or non-polar. Many amino acids are polar, but many are also non-polar, due to long carbon chain R-groups or aromatic R-groups on the amino acid. This is more of a general rule but not enough to dictate tertiary protein structure. Disulfide bridges are incorrect because that's just links of two sulfur atoms at different parts of the protein, which help to stabilize the shape; this has nothing to do with R-groups of amino acids.

Answer 4

http://www.brooklyn.cuny.edu/bc/ahp/LAD/C4b/C4b_proteinShape.html

Answer 5

I believe the answer is A. hydrophobic. Inside the biological membranes are lipids (hydrophobic) molecules. As you may know the membranes are lipid bilayers. In order to place proteins, which are polymers of amino acids, you would need to create an like-to-like environment. The R groups of amino acids will interact with this hydrophobic lipid bilayer environment and will need to display the same characteristics to keep the plasma membrane intact and not cause unwanted disruption. Therefore, R groups of amino acids in biological membranes should be hydrophobic.

All of the other answers involve charged, polar characteristics. Not something you would want in the non-polar environment found in biological membranes.