Aligning Sequences to Compare Apples to Apples
- Before you can compare sequences, you need to make sure that you are comparing stretches of DNA that are evolutionarily related—i.e., that they are homologous sequences.
- Two sequences need to be aligned, so that related parts of sequences are lined up against each other and compared.
![](images/slide-9-image.png)
Comparing non-homologous sequences to determine evolutionary relationships among species is like comparing apples to oranges.
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