The Following Questions Refer to the Information Below -Typically, Mutations That Modify the Active Site of an Enzyme

Short Answer

The following questions refer to the information below.
A researcher compared the nucleotide sequences of a homologous gene from five different species of mammals with the homologous human gene. The sequence homology between each species' version of the gene and the human gene is presented as a percentage of similarity.
$$\begin{array} { l c } \text { Species } & \text { Percentage } \\\hline \text { Chimpanzee } & 99.7 \\\text { Orangutan } & 98.6 \\\text { Baboon } & 97.2 \\\text { Rhesus Monkey } & 96.9 \\\text { Rabbit } & 93.7\end{array}$$

-Typically, mutations that modify the active site of an enzyme are more likely to be harmful than mutations that affect other parts of the enzyme. A hypothetical enzyme consists of four domains (A-D), and the amino acid sequences of these four domains have been determined in five related species. Given the proportion of amino acid homologies among the five species at each of the four domains, which domain probably contains the active site?
$$\begin{array} { c c } &\text { Percent age of Homologous } \\\text { Domain } & \text { Amino Acids } \\\hline \text { A } & 32 \% \\\text { B } & 8 \% \\\text { C } & 78 \% \\\text { D } & 45 \% \\\hline\end{array}$$