Question

what is the molecular composition of short tandem repeats?

Answer 1

Solution

Short tandem repeats (STRs) are segments of DNA that consist of 2–100 nucleotides repeated in tandem and in the same orientation, that can be repeated 5 to over 200 times.41 Most STRs are located in no-coding regions (DNA regions not involved in RNA production) of the genome.

Tendem repeats- ATTCG ATTCG ATTCG

• When between 10 and 60 nucleotides are repeated, it is called a minisatellite.
• Those with fewer are known as microsatellites or short tandem repeats.
• When exactly two nucleotides are repeated, it is called a dinucleotide repeat (for example: ACACACAC...).
• When three nucleotides are repeated, it is called a trinucleotide repeat (for example: CAGCAGCAGCAG...), and abnormalities in such regions can give rise to trinucleotide repeat disorders.
• When the repeat unit copy number is variable in the population being considered, it is called a variable number tandem repeat (VNTR). MeSH classifies variable number tandem repeats under minisatellites.