A Biologist Determined the Amounts of Several Amino Acids in Two

question 56

Multiple Choice

A biologist determined the amounts of several amino acids in two separate samples of pure protein. His data showed that Protein A contained 7% leucine, 12% alanine, 4% histidine, 2% cysteine, and 5% glycine. Interestingly, Protein B had the same percentages of the same amino acids. He concluded from this data that Proteins A and B are the same protein. Based on this information and his conclusion, determine which of the following is the correct statement regarding his findings:

• A) He is correct; the proteins have the same percentages of each amino acid, so they are identical protein molecules.
• B) He is incorrect;  there is no information about the amino acids sequence (which dictates the overall structure of a protein), so the two proteins could be very different in shape.
• C) He is correct; although there is no information on the amino acid sequence in each protein, the order of the amino acids is irrelevant. It's only the total number of each molecule that is important to structure.
• D) He is incorrect; he hasn't accounted at all for the effects of pH on the composition of the protein and its effects on the individual amino acids.
• E) He is partly correct; the percentage of the listed amino acids is the same in each protein, but Protein A is hydrophobic and Protein B is hydrophilic.

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Definitions:

Fever Production

The body's response to infection or illness, involving an increase in body temperature to help fight pathogens.

Capillary Permeability

The ability of substances to pass through the tiny blood vessels known as capillaries, either entering or exiting the bloodstream.

Chemotaxis

Attraction of living protoplasm (cells) to chemical stimuli.

Vasodilation

Increased diameter of blood vessels.