Question

what kinds of DNA regions are used for molecular clocks and why?

Answer 1

A molecular clock is a specific region of DNA which undergoes substitution but not insertion / deletion mutations, and which is subject to mutations at the same rates in different species. It is also necessary that mutations in sequences used as molecular clocks do not affect the fitness of the organism to survive - they are so called "neutral" mutations.

Answer 2

Make sure you hit the "Best Response" button if your question was answered, please.

@brparadox

Answer 3

got it?

Answer 4

but i mean like what kinds of dna is used not what a molecular clock is

Answer 5

non coding DNA sequences....!!!!!!!!

Answer 6

and why if you don't mind

Answer 7

There are some important conditions for using the molecular clock – any stretch of DNA that is subject to selection, for example, is not going to be a very useful source of clock data, as genetic differences will tend to be removed by selection; many genes that are vital to organismal function are therefore highly conserved, showing few differences between groups. For this reason, scientists tend to use either ‘synonymous changes’ in DNA – these are ‘silent’ differences that do not cause any change in gene function (protein structure, gene regulation, or whatever) – or \(\bf to~use~stretches~of~non-coding~DNA\), which appear to be not subject to natural selection and to evolve ‘neutrally’, just accumulating mutations with time.