Protein Similarities III
These are the actual data.
Species
Number of amino acids in cytochrome C different
from human
Chimpanzee
0
Rhesus monkey
1
Rabbit
9
Kangaroo
10
Whale
10
Cow, pig, sheep
10
Dog
11
Donkey
11
Horse
12
Hen, turkey
13
Rattlesnake
14
Tortoise
15
Tuna
21
Dogfish
23
Fly (Drosophila)
25
Moth
31
Wheat
36
Neurospora (fungus)
43
Yeast (also a fungus)
44
Data from Fitch and Margoliash 1970. The usefulness of amino acid and nucleotide sequences in evolutionary
studies. Evolutionary Biology 4:67-109.
Do the data in this table agree or disagree with the predictions made by the hypothesis? Explain.
1
Of course, this table shows only the number of differences between human cytochrome C and that of each
of these organisms. Dog and donkey both have cytochrome C proteins that differ from the human
cytochrome C by 11 amino acids. Does this mean that the cytochrome Cs of dog and donkey are the
same? Explain.
2
This diagram shows the % similarity in amino acid sequence of cytochrome C proteins found in a
number of organisms. To find the % similarity between any two organisms, trace the lines from those
organisms back to the left until they meet; then look at the bottom to read off the % similarity.
How similar (in percent) are the cytochrome c sequences of Candida and tuna?
How similar (in percent) are the cytochrome c sequences of horse and donkey?
How similar (in percent) are the cytochrome c sequences of whale and tuna?
How similar (in percent) are the cytochrome c sequences of whale and donkey?
3
What can you conclude about the hypothesis presented in the previous handout (see below)? Explain.
Now
H RM CH C HO R W F
K S Y Wh
Then
How could you revise the hypothesis in the diagram to better agree with the cytochrome c data?
Diagram the revised hypothesis on a separate sheet of paper and attach it to this handout..
4