how might similarties and differences in genetic codes to be used to determine how closely related different species are?

Question

anonymous · Answer

Hmm...does the question actually mean similarities and differences in gene sequences? You can look up molecular phylogeny, or molecular clock.

anonymous · Answer

sorry i asked the question wrong. How might similarities and differences in genetic codes, or the proteins built as a
 result of these codes, be used to determine how closely related different species are?

anonymous · Answer

OK, then the question is phrased badly and indeed it is asking about the genetic sequences. DNA sequences change over generations as a result of random mutation, so more distantly related organisms have more DNA sequence differences. Again, look up molecular clock or molecular phylogeny for a fuller explanation.