Prompt Comparing amino acid sequences in proteins has been used to determine the relatedness of organisms. Below is a graphic that shows the amino acid sequence differences between different organisms for a protein keratin. Changes in amino acid sequences are known to cause changes in structure of proteins.

Species ASpecies BSpecies CSpecies DSpecies E
Species A
4
11
19
1
Species B
12
18
5
Species C
8
10
Species D
20
Species E
Part A. Consider species A, D, and E. Using the data provided, describe how the structures of their keratin proteins would compare.

Part B. Keratin is made up of about 450 amino acids. Determine the similarity in percentages between species A and B, A and C, and B and C. Explain how amino acid sequences can be used in determining how closely related two species are.

Part C. Based on this data, predict which two species would be more closely related to one another.

Part D. Justify your predictions to part C.