Protein and DNA homology
To calculate homology between to protein or DNA sequences, follow this procedure.
Example with Proteins
Enter this web-page: http://www.ncbi.nlm.nih.gov/
Find 'Protein' in the box saying 'All databases'
Enter the name of the protein and the name of the organism. e.g 'Reverse transcriptase bombyx'
Chose two or more sequences of approximatly same length. preferentially those that are not partial sequences. e.g. BAD86656, AAA17752 and AAC13649.
Go back to the main page, scroll down and find BLAST.
Select 'protein blast'
Select 'Align two or more sequences'
Copy one number into the upper field and the two other into the lower.
Scroll down and press 'BLAST'
Now the program calculates the homology between the first sequence and the two others.
Actually there is onlyone result, but that is because there iano homology between BAD86656 and AAA17752!
Example with DNA
The Mitochondrial genome, mtDNA, is the simplest to work with.
E.g. the homology between Human, Chimp, Gorilla, Orangutan and various Gibbons can be found by the same procedure as described above. Use 'Nucleotide BLAST' adn the following GenBank numbers:
Homo sapiens: HQ260949
Pan troglodytes: JF727179
Pan paniscus: HM015213
Gorilla gorilla: KF914214
Gorilla beringei: KF914213
Pongo pygmaeus: NC_001646
Pongo abelii: NC_002083
Various Gibbons: KY250074, HQ622806, HQ622776, NC_014047
If you work out the homology between all of these, you end up with a clear pattern.
The two species og Pan are closests, the two species of Gorillaare closest, The two species ofOrangutan are closest, The four species of Gibbons are closts.
Nothing controversial there.
But, most interesting: Chimps (Pan) are closer to Humans than to any of the other species.