DNA replication

Question 1

The semi-conservative replication of DNA ensures

Answer 1

Genetic continuity between generations of cells

Question 2

The process of semi-conservative replication of DNA

Answer 2

Unwinding of the double helix

Breakage of hydrogen bonds between complementary bases in the polynucleotide strands

The role of DNA helicase in unwinding DNA and breaking its hydrogen bonds

Attraction of new DNA nucleotides to exposed bases on template strands and base pairing

The role of DNA polymerase in the condensation reaction that joins adjacent nucleotides

Question 3

Evaluation of Watson-Crick’s model of semi-conservative replication

Answer 3

Watson and Crick were two scientists who worked together to confirm the double-helix structure of DNA in 1953
Watson and Crick also came up with a model by which DNA might be replicated:

This theory was called semi-conservative DNA replication

The theory is based upon the specific hydrogen bonding between pairs of nitrogenous bases (A+T and C+G) being used during replication to conserve the genetic sequence

However, this was just a theory, another theory suggested DNA replicated ‘conservatively’

The theory of conservative DNA replication suggested that the strands of the original DNA molecule would stay together, and the new, replicated DNA molecule would be made out of two brand new strands

Watson and Crick’s theory of semi-conservative DNA replication was later proved to be correct by the work of two other scientists,
Meselson and Stahl

They used bacteria and two nitrogen isotopes, a heavy form (15N) and the normal, lighter form (14N), to prove this