Question

Select all that are true. A short tandem repeat (STR):

Answer 1

Answer:

C. Is a repeated sequence of DNA in a non- coding sequence

D. Can be composed of a variable number of repeats in different people

Explanation:

Short Tandem Repeats (STRs) are short DNA motifs, i.e., short nucleotide repeat units (generally 2-7 base pairs in size) that may have a different number of repeats among individuals (alleles). Polymorphic STR sequences are very useful genetic markers and therefore they are used for different purposes, e.g., for constructing genome linkage maps, identification of individuals and/or populations, paternity testing, etc. For example, in the USA, the Combined DNA Index System (CODIS) is a databank that stores different DNA profiles based on 13 core STR loci which are used in forensic identity testing.