SNAB A2 - Infection , immunity and forensics.

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  • Created by: charlotte
  • Created on: 19-01-11 15:47

Forensic Biology -

Identifying the body..

Fingerprints can be taken , They are unique to an individual and last a life time . Fingerprints are taken using fine aliminium powders . Once the fingerprint is obtained the four main type of finger print can be classified - , an arch , a tented arch , a whorl and a loop. This is known as , the henry classification. Arch patterns are rare and the loop is most common.

Dental records can be taken. Dental records are the best way for people with no fingerprint files. Teeth and filling decay slowly . A forensic dentist makes a chart of the teeth , including dental work , fillings and any missing teeth. This is then compared with dental records of the missing person. The forensic dentist may also look at the development of the teeth to determine the age.

DNA fingerprinting may be used . Also known as DNA profiling. This relies on the fact that apart from identical twins everyones DNA is unique . The non coding blocks are called are called introns and they are inherited in the same way as any gene.

Mini satellites contain 20 - 50 base pairs.

Micro satellites contain 2 - 4 base pairs.

A DNA sample is treated with a restriction enzyme. .This cuts the DNA into fragments of double stranded DNA . .The DNA fragments are seperated using  Gel  Electro phoresis . .The smaller fragments with fewer repeats of sattelite pass through the gel quicker.  .The fragments are transferred to the nylon membrane using southern blotting. .The membrane is washed with a labelled DNA probe that binds to the repeated sequence producing visible bands. .A single band appears where the maternal and paternal chromosomes have the same number of satellite repeats at the locus. . If the 2 chromosomes each have a different number of repeats there will be 2 bands. . Only those that bound the labelled probe show up : - this resulting image is called a . . D N A finger print.

Polymerase  Chain  Reaction.. ..

The uk forensic servise uses P C  R technique . this is an automated gel electrophoresis for D N A fingerprinting. PCR reaction rapidly multiplies DNA meaning forensics only need to use small deposits such…




great notes thank 

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