DNA (Forensics)

Cards for DNA in Forensic Module

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  • Created by: Nelly
  • Created on: 01-01-12 23:02

DNA

DEOXYRIBONUCLEIC ACID

  • Molecule that carries instructions for our development.
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Genomes

Genome = All our DNA

  • Genome - made of chromosomes
  • 23 pairs of chromosomes (22 autosomes + 1pair sex)
  • 99.9% of our genomes are same from person to person
  • Identical twins have same DNA, different fingerprints.
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Chromosomes

Chromosomes in pairs

  • One from Mum
  • One from Dad

Location on Chromosomes = LOCUS

Locus on one of the genes in chromosomes = ALLELE

Combination of alles at a locus = GENOTYPE

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Chromosomes

  • If both CHROMOSOMES are same = HOMOZYGOUS
  • If CHROMOSOMES differ  = HETEROZYGOUS
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Development of DNA

  • 1900 - Blood groups discovered.
  • 1915 - first blood tests developed (ABO types) and potential for typing blood investigated.
  • 1940-50 - Other blood groups found.
  • 1985 - Sir Alec Jeffreys publishes first DNA fingerprint
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Biological Evidence

All cells except red blood cels have a nucleus therefore contain DNA

DNA Extraction:

  • Break open cell
  • Remove proteins
  • Revocer DNA
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Application

Disaster Victim ID

Problems:

  • Fragmented remains
  • Mised remains
  • Bodies badly degraded
  • Need suitable reference sample for comparison

Can:

  • Identify matching bodyparts
  • ID by matching DNA profile to personal items
  • ID by comparing to known relative


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Application

Non-Human

  • Animal DNA can be used to link suspect to crime scene
  • Species identification
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National DNA Database

  • Set up 1995
  • Samples can be collected from anyone arrested
  • DNA kept  indefinitely
  • Owned by ACPO
  • Managed by Home Office
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