Site author Richard Steane
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Genetic Fingerprinting

Genetic fingerprinting or DNA profiling is a technique which uses the individuality of DNA molecules to distinguish between organisms, or to show the relationships between them.

This technique relies on a number of quite technical processes: The resulting genetic profiles consist of a series of bands which vary in thickness and spread out to occupy different positions.

Genetic profiling has a number of applications, including forensic science:
identification of suspects based on crime scene samples (blood, body cells, semen samples)
proving (or disproving) paternity

It can also be used to show the amount of biodiversity in an animal population in the wild, or in a zoo.

This chart shows the genetic profiles of a family consisting of a mother a father and two children.
It may be helpful if you move the mouse cursor over the diagram to get some colour-coded clues.
Compare the bands for child 1 (or child 2) with the parents. What do you notice?

> Each band is at the same position (and same thickness) as one or the other (or both) of the parents.
> Every one of the children's bands matches up to one or other of their parents.

Do the two children have the same genetic profile?

> No - they have some of the same bands but lots of differences.

What proportion of bands does each child share with one of the parents?

> Half the number

How do you explain this?

> When sperms and eggs are made, only half of each parent's chromosomes, genes and DNA are passed on into the sex cells (gametes).
> At fertilisation, male and female gametes combine and their DNA is also combined, recreating a full set of chromosomes, genes and DNA.

What result would identical twins give?
> Exactly the same- unlike prints on their fingers!

Web references

DNA profiling
From Wikipedia, the free encyclopedia

The first genetic fingerprint, 1984.

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