DNA profiling

Question 1

Describe PCR Step 1

Answer 1

DNA strand is heated to 95C and double strand separates to 2 strands

Question 2

Describe PCR Step 2

Answer 2

DNA sample is cooled to 55C and primer attaches to start of STR sequence
Primer - small piece of DNA complementary to STR with fluorescent markers attached

Question 3

Describe PCR Step 3

Answer 3

DNA sample heated to 70C and DNA polymerase attaches, nucleotides added and 2 strands form

Question 4

Describe restriction enzymes

Answer 4

Used to cut the DNA into fragments
Blunt and sticky ends (exposed areas)
Cut at recognition sites

Question 5

Describe Gel Electrophoresis

Answer 5

DNA is loaded into agrose gel walls
Negatively charged DNA moves through the gel to the positive electrode
shorter fragments move faster and further

Question 6

Describe Southern Blotting

Answer 6

DNA is transferred to a nylon sheet where its soaked up (tough = nylon)
Strong alkali denatures DNA into 2 single stranfs
DNA probe is added (complementary to STR and have radioactive/fluroscent markers
Viewed using UV light or X rays

Question 7

Describe the uses of DNA profiling

Answer 7

Forensic uses - IDing the body
Genetic and paternity tests
Evolutionary relationships