DNA (Forensics)

DEOXYRIBONUCLEIC ACID

• Molecule that carries instructions for our development.

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.
  

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

• If both CHROMOSOMES are same = HOMOZYGOUS

• If CHROMOSOMES differ  = HETEROZYGOUS

• 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

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

DNA Extraction:

• Break open cell
• Remove proteins
• Revocer DNA

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
  

Non-Human

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

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