DNA PROFILING

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DNA PROFILING
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DNA PROFILING

• 1980 - American researchers discovered
  non-coding regions of DNA
• 1984 - Professor Alec Jeffreys developed the
  process of DNA profiling

• 1987 - First conviction based on DNA
  evidence

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SYLLABUS Section 2.5.4

• Definition
• Stages involved
• Any two applications

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DNA PROFILING
A process or technique of analysis revealing
unique patterns of an individuals DNA
involving non-coding regions
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NON-CODING REGIONS
(VNTR)
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STAGES INVOLVED

• Cells broken down to release DNA
• DNA strands cut into fragments
• Fragments separated
• Pattern of fragments analysed

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1. DNA EXTRACTION
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• 2. DNA CUTTING

• 3. FRAGMENT SEPARATION

The samples containing the fragments are
pipetted into individual wells in a gel
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ELECTROPHORESIS

• Fragments separated by length
• DNA (negatively charged)
• Moves towards ve terminal
• Shorter fragments move faster

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4.DNA TRANSFER

• DNA split into single strands using alkaline
  solution
• DNA fragments transferred from gel to filter
  paper or nylon membrane
• (This is called Southern blotting)
• Gel, with filter paper attached, is removed
  separated

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5. ANALYSIS
Radioactive probe in solution binds to DNA
Revealing a pattern of bands
X-ray film
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HOW DNA PROBES WORK
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DNA PROFILE
Puppy
Sire
Dam
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SOME APPLICATIONS

• Forensic Science

• Family Relationships
• Health Care

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FORENSIC SCIENCE
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FAMILY RELATIONSHIPS
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HEALTH CARE
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DEVELOPMENTS IN DNA PROFILING
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COMMON CONCERNS

• Quality of sample
• Mistakes and inaccuracy
• Interpretation
• Privacy
• Evidence from criminal investigations
• Who should use DNA fingerprinting
• Cost effective
• Ethnic problems

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TYPES OF PROBES

• Multi-locus
• Bind to a large number of VNTRs at different
  locations
• Produce a bar code pattern

• Single-locus
• Bind to one type of VNTR at a specific location
• Produce a two band pattern

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