Question

A mutation that occurs in DNA can cause an amino acid substitution in the encoded protein. Amino acid substitutions are described as conservative when the amino acid in the mutated protein has chemical properties similar to those of the amino acid it has replaced. Identify different examples of pairs of amino acids that could be involved in conservative substitutions.

(a) Glycine and Alanine
(b) Leucine and Isoleucine
(c) Aspartic acid and Glutamic acid
(d) Histidine and Proline

Answer 1

Conservative substitutions in DNA mutations involve swapping one amino acid for another with similar chemical properties. Examples include Glycine (Gly) and Alanine (Ala), Leucine (Leu) and Isoleucine (Ile), and Aspartic acid (Asp) and Glutamic acid (Glu). Histidine (His) to Proline (Pro) substitution is not conservative due to differing side chains.

correct answer is d. Histidine and Proline

Step-by-step explanation:

A mutation that leads to an amino acid substitution can have varying effects on a protein's function depending on the chemical properties of the amino acids involved. A conservative substitution involves replacing one amino acid with another that has similar chemical properties, which may result in minimal structural and functional changes to the protein.

Examples of pairs of amino acids that could be involved in conservative substitutions are:

Glycine (Gly) and Alanine (Ala) - both small, non-polar amino acids.

Leucine (Leu) and Isoleucine (Ile) - both aliphatic, hydrophobic amino acids.

Aspartic acid (Asp) and Glutamic acid (Glu) - both acidic amino acids with carboxylate side chains.

However, the substitution between Histidine (His) and Proline (Pro) is not generally considered conservative because their side chains and consequent chemical properties differ significantly, which can lead to more pronounced changes in the protein's structure and function.

correct answer is d. Histidine and Proline.