Tandem Repeats and RFLPs

Tandem repeats

Sequences of nucleotides that repeat, occurring one after the other in an uninterrupted fashion

Where are tandem repeats found?

In prokaryotic and eukaryotic genomes in coding and non-coding regions

Tandem repeats differ in?

Length as well as in the number of repeats

From one person to another, what is the same, and what varies?

* The repeated sequences are the same
* The number of times they repeat varies

What are the two types of tandem repeats?

* Short tandem repeats (STRs)
* Variable number tandem repeats (VNTRs)

STRs

* Short tandem repeats
* 2-10 nucleotides
* May be repeated several dozen times

VNTRs

* Variable number tandem repeats
* 10-100 nucleotides
* Much longer than STRs

What is the difference between STRs and VNTRs

The number of times each unit is repeated

Restriction fragment length polymorphism (RFLPs) refer to:

Restriction fragments that differ in size from each other

Restricting DNA in haploid and diploid (polyploid) species will frequently yield fragments of ? sizes in different individuals

1. varying

What are the causes of RFLPs?

1. Point mutations
2. Large-scale insertions and deletions


1. Transposable elements
2. Tandem repeats
3. Translocations

What are some applications of RFLPs

* VNTRs are used for DNA fingerprinting
* STRs are used in law enforcement
* STRs are very similar between closely related individuals
* Unrelated individuals are extremely unlikely to carry the same STRs
* STRs are frequently used in genealogical and paternity tests
* They can be used to identify the presence of genetic (and thus heritable) diseases
* VNTRs can be used to determine the origin of an outbreak
* RFLPs can be used to measure genetic divergence between different populations or related species
* Measure of the total number of RFLP differences represents a measure of genetic difference
* RFLPs are important in studies of evolution