Answer:
A) Species A and E are more closely related than either species are related to species D.
B) Between A and B = 99.1%
Between species A and C =97.5%
Between species B and C = 97.3%
Similarity in amino acids sequence reflects similarity in DNA sequence
C) Species A and E are most closely related
D) Species A and E have the most similarity in amino acid sequence, and hence DNA sequence.
Explanation:
A) The amino acid sequences of the protein, keratin, in species A and D has a difference of about 19 whereas species A and E have a difference of only 1. Therefore, it means that keratin in species A and D will have differences in structure whereas between species A and E, they would have almost the same structure.
Also, species D and E have a difference of 20 in their amino acids sequence, therefore, the structure of keratin in both species will have differences in structure.
B) Similarity between A and B:
450 - 4 = 446
In percentage: 446/450 × 100% = 99.1%
Similarity between A and C:
450 - 11 = 439
In percentage: 439/450 × 100% = 97.5%
Similarity between B and C:
450 -12 = 438
In percentage: 438/450 × 100% = 97.3%
The sequence of DNA of species determines their amino acid sequences because information in DNA is transcribed to RNA which are then used to make proteins. Therefore, if a species are very closely related, they are expected to have very similar genetic sequences and thus proteins too. This is reflected in similarity between amino acid sequences in their proteins.
C). Species A and E are most closely related.
D) Species A and E have only a single difference in their amino acids sequence for Keratin. This translates to about 99.7% similarity which is the highest among all the species compared. Therefore, species A and E are most closely related.
