Question

Mutations in the nucleic acid sequence of a gene can sometimes direct the substitution of one amino acid for another in the encoded protein. Which amino acid substitution would be most likely to severely disrupt the normal structure of a protein?
A) alanine → glycineB) asparagine → threonineC) leucine → isoleucineD) methionine → arginineE) tryptophan → phenylalanine

Answer 1

An answer

D) Methionine → Arginine, will most likely disrupt the normal structure of a protein.

Explanation:

Methionine is an hydrophobic amino acid thus it is involved with hydrophobic interactions.

Arginine is a polar charged amino acid, it is involved with electrostatic and dipole interactions.

Substituting an hydrophobic amino acid with a polar charged amino acid will therefore disrupt the structure of the protein because their side chains interact differently. Especially their Tertiary and Quaternary structures which involve side chains interactions.