You are given a protein with the following amino acid sequence: methionine (nonpolar)-glycine (nonpolar)-serine (polar)-alanine (nonpolar)-lysine (polar)
If an amino acid substitution occurred in this polypeptide chain, predict which option would have the most
significant impact on the structure and function of the protein.
a. Serine is replaced by lysine (polar)
b. Glycine is replaced by alanine (nonpolar)
c. Alanine is replaced by leucine (nonpolar)
d. Lysine is replaced by tryptophan (nonpolar)
?

 d. Lysine is replaced by tryptophan (nonpolar)

Explanation:

Amino acid substitutions can have varying affects on the protein function, depending on the specific substitution and the location of the substitution.

If the substitution occurs in an important region, for example an enzyme active site, then the function of the protein could be destroyed.

Additionally, if the substitution replaces the amino acid with a highly different amino acid with different properties (eg. polarity), it could alter the structure and function of the protein.

Replacing lysine (polar) with a tryptophan (non-polar) changes the properties of the amino acid at that location, whereas the other substitutions do not.

is this a psat question, if so do not cheat try your best.