Analyze your gel

In this example bands marked with different colors for each dideoxynuclotides, represent the last nucleotide in each strand run through the gel. The shortest strand migrates the farthest from the starting point. Therefore if you read from bottom to top, you can read the entire sequence.

Now that we know about how to sequence a strand of DNA, how can use that information to tell how closely related two groups of animals are? The first step is to look at their DNA sequences and count the differences.

Compare the sequences from three different species shown below:

Between sequence 1 and 2 there are 2 differences.
Between sequence 1 and 3 there are 4 differences.
Between sequence 2 and 3 there are 6 differences.
If we look at it like a mileage chart, it looks like this.

1 2 3
1 X

2 2 X
3 4 6 X
So which two sequences are more similar?

1 and 2, so therefore these two animals should be more closely related than say 1 and 3, where there were 4 differences

Sequence Tortoise DNA

Count the chromosomes of the Malagasy brown lemur