DNA Replication

Question 1

Semi Conservative Replication

Answer 1

half the strands on each new DNA molecule are from the original DNA molecule
Ensures genetic continuity between cell generations

Question 2

First Stage

Answer 2

DNA helicase breaks H-Bonds between bases on two polynucleotide strands
double helix unwinds to form two single polynucleotide strands

Question 3

Second Stage

Answer 3

original single strands act as templates for new strands
Complementary base pairing:
free DNA nucleotides attracted to complementary exposed bases on template strand
A=>T C=>G

Question 4

Third Stage

Answer 4

Condensation reactions join nucleotides of new strands together (DNA polymerase)
H-Bonds form between bases on original and new strands
helix reforms

Question 5

Fourth Stage

Answer 5

Each new DNA molecule contains one strand from original DNA and one new strand

Question 6

DNA polymerase…..

Answer 6

moves in opposite was along antiparallel DNA strands
one end is 3’
other is 5’
active site of DNA polymerase only complementary to 3’ of newly forming DNA strand => can only add to 3’
new strand made in 5’ to 3’ direction while DNA Polymerase works 3’ to 5’ on template =>
Opposite directions on each template strand as strands in double helix are anti parallel