DNA Profiling

Question 1

What is a short tandem repeat?

Answer 1

Short, repeated sequences of bases in the DNA

Question 2

What does PCR do to DNA?

Answer 2

Amplifies it so it can be used in DNA profiling

Question 3

What does PCR use?

Answer 3

DNA primers

Question 4

What are DNA primers?

Answer 4

Short sequences of DNA complementary to the DNA adjacent to the STR

Question 5

What are the PCR temperatures?

Answer 5

1) 90-95C for 30 seconds
2) 50-60C for 20 seconds
3) 72C for a minute
4) Repeat

Question 6

What happens at each temperature in PCR?

Answer 6

1) 90-95C DNA strand separates
2) 50-60C Primers bind to DNA strands
3) 72C Polymerase builds up complementary strands of DNA

Question 7

Name the stages in gel electrophoresis

Answer 7

• Double stranded DNA cut into fragments by endonucleases
• Fragments are loaded into agarose gel tank
• Negatively charged DNA moves to positive electrode
• DNA transferred to nylon by drawing solution up
• Membrane placed in bag with DNA probe. Binds to fragments with complementary sequence
• Fluorescent and viewed using UV light or Radioactive and viewed using X ray

Question 8

Name the stages in PCR

Answer 8

• Primers (endonucleases) used
• Primers marked with fluorescent tags
• Sample placed in reaction tube with DNA polymerase, primers and nucleotides
• Cycle of temperatures