1.2 Replication Of DNA

Question 1

DNA Replication- Stage 1

Answer 1

DNA unwinds and weak hydrogen bonds break between bases

Allows two strands to unzip into two template strands called a replication fork

Question 2

DNA Replication- Stage 2

Answer 2

Primers at start of leading strand allow DNA polymerase to add free complementary DNA nucleotides

Nucleotides bind to 3’ end to make new strand

Question 3

DNA Replication- Stage 3

Answer 3

Several primers are added to lagging strand

DNA polymerase adds free complementary DNA nucleotides in fragments

These fragments are joined together by ligase

Question 4

Polymerase Chain Reaction

Answer 4

Amplification of DNA to make a large quantity of DNA fragment

Question 5

PCR- Stage 1

Answer 5

DNA sample heated to 92-98 degrees Celsius

Breaks weak hydrogen bonds between bases and separates DNA strands

Question 6

PCR- Stage 2

Answer 6

DNA sample cooled to 50-65 degree Celsius

Allows primers to bind to DNA strands and stabilise hydrogen bonds

Question 7

PCR- Stage 3

Answer 7

DNA sample heated to 70-80 degree Celsius

Allows heat tolerant DNA polymerase to replicate DNA by adding nucleotides to 3’ end

Question 8

PCR- Stage 4

Answer 8

Cycle repeated many times to amplify DNA

Question 9

Uses of PCR

Answer 9

Solve crimes

Settle paternity suits

Diagnose genetic disorders

Question 10

PCR requirements

Answer 10

DNA template strand

Two complementary primers

Four DNA nucleotides

pH buffer

Heat tolerant DNA polymerase

Thermal cycler machine