Question

In Marker Analysis, how are STRs related to alleles? Be sure to define each term (STR and allele) and explain how the two result in different band patterns when run in gel electrophroresis.

Answer 1

Answer:

The number of STR repeats is unique and therefore it is considered as an allele of that locus

Explanation:

Short Tandem Repeats (STRs), also known as microsatellites or simple sequence repeats (SSRs), are short DNA sequences with a size of 1-6 nucleotide bases which may be many times repeated in tandem. STRs localize in specific regions of the genome (loci) and therefore they are molecular markers. Gel electrophoresis a technique used to separate DNA fragments based on their size. In consequence, the pattern of STR repeats or 'alleles' obtained by electrophoresis can be used to identify individuals. In a gel electrophoresis, STR markers produce different bands that run more slowly or faster on the gel in different lanes according to their size (e.g., more slowly >> higher size of the STR sequence), and thereby STR alleles are unique and serve to identify individuals.