Question

Why does a comparison of histone protein sequences show 0 non--synonymous mutations between humans

and mice whereas Growth Hormone proteins show a higher rate of non-synonymous mutations and both
show a very high rate of silent mutations in this comparison?
How can positive selection be demonstrated at the molecular level

Answer 1

A comparison of histone protein sequences between humans and mice shows 0 non-synonymous mutations, while Growth Hormone proteins show a higher rate of non-synonymous mutations. Both histone proteins and Growth Hormone proteins show a high rate of silent mutations. Positive selection can be demonstrated at the molecular level by analyzing the non-synonymous/synonymous substitution rates.

Step-by-step explanation:

A comparison of histone protein sequences between humans and mice shows 0 non-synonymous mutations, while Growth Hormone proteins show a higher rate of non-synonymous mutations. Both histone proteins and Growth Hormone proteins show a high rate of silent mutations. A comparison of non-synonymous/synonymous substitution rates can provide evidence of positive selection at the molecular level. If the rate ratio is greater than 1, it suggests positive selection has occurred.