noncoding DNA,

Question

Hello, in noncoding DNA, there is repetitive DNA: heterchromatin and transposon repeats (retrotransponsons and DNA transponsons). where do both of these repetitive sequences come from? are we born with them/inherit them from our parents (eg the retroviruses) or do they form after, and if so how?

Answer 1

Hi Charlotte,

 

An organism inherits all its DNA, coding as well as non-coding DNA from the parents. Chromosomal arms are made of euchromatin and centromeres are comprised of heterochromatin. An organism inherits chromosomes and therefore, inherits heterochromatin as well.  An organism inherits repetitive DNA from parents, however, number of repeats in a stretch of repetitive DNA change in the life time of an organism based on a number of biological factors. One good example is telomere length, as we age, our telomeres decrease in length as effect of aging.  Transposons are mobile genetic elements that reside on chromosomes. They need particular environment to transpose or move. An organism is born with transposons, under certain conditions transposons move from one location to another, it could be same chromosome or a different one. Sometimes during the course of their transposition their sequence is altered as they might lose some sequence or might pick up additional base pairs through replication.

 

I hope I have answered all your questions, if anything is unclear then please feel free to post again.

 

Naina B