A mutation in the gene coding for a single-polypeptide enzyme results in the substitution of the amino acid serine, which has a polar R group, by the amino acid phenylalanine, which has a nonpolar R group. When researchers test the catalysis of the normal enzyme and the mutated enzyme, they find that the mutated enzyme has much lower activity than the normal enzyme does. Which of the following most likely explains how the amino acid substitution has resulted in decreased catalytic activity by the mutated enzyme?

The substitution altered the secondary and tertiary structure of the enzyme so that the mutated enzyme folds into a different shape than the normal enzyme does.

The question is incomplete, the complete question is;

A mutation in the gene coding, for a single-polypeptide enzyme results in the substitution of the amino acid serine, which has a polar R group, by the amino acid phenylalanine, which has a non-polar R group. When researchers test the catalysis of the normal enzyme and the mutated enzyme, they find that the mutated enzyme has a much lower activity than the normal enzyme does. Which of the following most likely explains how the amino acid substitution has resulted in decrease catalytic activity by the mutated enzyme?

A. The substitution decreased the mass of the enzyme so that the mutated enzyme binds more weakly yo the substrate than the normal enzyme does.

B. The substitution altered the secondary and tertiary structure of the enzyme so that the mutated enzyme folds into a different shape than the normal enzyme does

C. The substitution caused many copied of the mutated enzyme to cluster together and compete for substrate to bind.

D. The substitution caused the directionality of the enzyme to change such that the amino terminus of the normal enzyme has become the carboxyl terminus of the mutated enzyme

First of all, we must recognize that an enzyme is a a protein. These proteins serve as biological catalysts. The are composed of a sequence of amino acids.Every protein  has;

The secondary and tertiary structure of the protein affects its activity. The secondary structure of a protein refers to its amino acid sequence. Hence, when phenylalanine is substituted for serine, the secondary structure of the protein has been altered. This affects the hydrogen - bonded interaction of the groups on the protein.

Also, the alteration of this hydrogen bonded sequence of amino acids also alters the overall three dimensional or tertiary structure of the protein. Since the interaction of an enzyme with its substrate depends on its overall structure, the mutated enzyme can no longer interact effectively with the substrate hence it shows a reduced activity compared to the normal enzyme.

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The correct answer is: The substitution altered the secondary and tertiary structure of the enzyme so that the mutated enzyme folds into a different shape than the normal enzyme does.

Explanation:

In the given condition, the substitution mutation of gene causes a replacement of serine by phenylalanine amino acids which causes a reduction in the activity of the enzyme.  Since serine is polar and has -OH or hydroxy group involves the information of binding of biological catalyst to the substrate.

The primary structure of a protein is significant which finalizes the number of amino acids their sequence. The mutation of protein also affects both secondary and tertiary structures as it disturbs the structure of the protein and affects the catalytic activity as well as the binding affinity of the substrate.

the substitution of serin by phenylalanine does not affect or influence the mass of enzyme.