1.5.2 Replication

Question 1

Why is semi-conservative replication important

Answer 1

Ensures genetic continuity between generations of cells

Question 2

DNA helicase

Answer 2

Breaks the hydrogen bonds between bases on the two polynucleotide DNA strands. Makes helix unwind to form two single strands

Question 3

Template strands

Answer 3

Each original single strand acts as a template for a new strand

Question 4

Complementary base pairing

Answer 4

Free-floating DNA nucleotides are attracted to their complementary exposed base on each original strand. AT, CG

Question 5

Condensation reactions joins nucleotides

Answer 5

Catalysed by DNA polymerase to join the nucleotides and form a new strand. Hydrogen bonds form between the bases on the original and new strands

Question 6

Antiparallel strands

Answer 6

They run in opposing directions, from 3 prime to 5 prime

Question 7

Active site of DNA polymerase

Answer 7

Only complementary to 3 prime end of new strand, so it can only add nucleotides to new strand at 3 prime end

Question 8

Meselson and Stahl

Answer 8

Experiment using two isotopes of nitrogen (heavy and light). Second generation of bacteria with light and heavy nitrogen was centrifuged and had a band in the middle between the light and heavy bands