polymerase chain reaction

Question 1

what is PCR used for?

Answer 1

• amplifying DNA

Question 2

step 1 and why

Answer 2

Heat to 95 degrees

- breaks Hydrogen bonds so DNA becomes single stranded

Question 3

step 2 and why

Answer 3

Cool to 50 degrees

• allows primers to bind via complementary base pairing (H-bonds reform)
• so DNA becomes double stranded
• So DNA polymerase can bind

Question 4

step 3 and why

Answer 4

Heat to 70 degrees

• so rate of reaction is fast
• DNA polymerase adds complementary nucleotides forming phosphodiester bonds

Question 5

step 4 and why

Answer 5

repeat 3 stages because each cycle doubles the DNA

Question 6

primers

Answer 6

short sequences of DNA complementary to the start of the DNA sample