DNA profiling involves the (partial) sequencing of genomes.
Profiles tend to focus on areas of satellite (junk) DNA which vary significantly between individuals.
Why use junk DNA for profiling: by sequencing a number of sections a unique ‘genetic fingerprint’ can be created for an individual.
Two uses of DNA profiling are paternity cases and forensic investigations.
Gel Electrophoresis
This laboratory technique is used to separate fragments of DNA in an effort to identify its origin.
Enzymes are used to chop up the long filaments of DNA in varying sized fragments. The DNA fragments are place into small wells (holes) in the gel which are aligned along one end. The gel is exposed to an electric current – positive on one side and negative on the other.
The effect is the biggest, heavies and least charged particles don’t move easily through the gel so they get stuck very close to the wells they were in at the origin. The smallest, least massive and most charged particles pass through the gel to the other side with little difficulty. Intermediate particles are distributed in between.
In the end, the fragments leave a banded pattern of DNA.
Outline the process of DNA profiling (genetic fingerprinting), including ways in which it can be used. (6)
· Sample of DNA is obtained from hair
· Satellite DNA (repetitive sequences) are used for profiling
· Amplification of DNA by polymerase chain reaction
· Cutting DNA into fragments of DNA by electrophoresis
· Separation according to the length of the fragments
· Pattern of bands obtained with DNA from different individuals
· Used for criminal investigations
· Used to check paternity
· Used to check whether two organisms are clones
