Identifying a Body

Question 1

Describe first stage in DNA profiling

Answer 1

• after DNA extracted, it is amplified by
  Polymerase chain reaction
  1) denaturation - heated at 95C to break H bonds between bases
  2) cooled to 50-60C and then heated back to 70
  3) annealing - DNA polymerase bind primers to DNA strand to create copy
• repeated to create many copies

Question 2

Describe second stage of DNA profiling

Answer 2

Gel electrophoresis
- separates fragments according to size on agarose gel
1) fragments added to wells of an agarose gel
2) current passed through gel; as DNA is negatively charged, moves from neg to pos
3) smaller fragments travel faster, so move further down gel in same amount of time
4) Southern blogging or UV tagging makes bonding visible

Question 3

What are used of DNA profiling?

Answer 3

Paternity tests, determining ancestry, criminal cases, evolutionary links