Estimating evolutionary time periods by employing gene product differences generates a continuum of very slow changes to relatively rapid changes. Nuclear gene products change(mutate) slower than mitochondrial gene products, which can change 5-10 times as fast. for this reason, mitochondria are often used when comparing closely related species.
One of the enzymes in mitochondria, NAD dehydrogenase, is mitochondrially encoded. when the first 75 amino acids in NAD dehydrogenase are compared between humans, gorillas and orangutans, the data in the table are obtained. Note that nucleotides differences can occur that do not necessarily cause a difference in the amino acid, since the code is degenerative.
comparing Amino acid differences Nucleotide differences
Human and Gorilla 5 13
Human and Orangutan 8 19
Gorilla and Orangutan 9 26
a)what percentage of the amino acids demonstrate differences between human and gorilla, human and orangutan, and gorilla and orangutan?
b)what percentage of nucleotides demonstrate differences between human and gorilla, human and orangutan, and gorilla and orangutan?
c)Do gorilla or orangutan have NAD dehydrogenase more similar to that of human?
d)Is the gorilla enzyme closer to that of humans or orangutans?
e) the gorilla and human common ancestor separated from the orangutan ancestor about 10.5 million years ago. Gorillas and humans had a common ancestor about 10 million years ago. How many years elapse, on average, for each mutation in amino acids? nucleotides?