Theme 4 - Module 2 (DNA Replication)

Question 1

What was Watson and Crick’s hypothesis for how DNA replicates?

Answer 1

Proposed that DNA consists of a pair of template chains which are complementary to each other.

Prior to replication, the hydrogen bonds are broken between these complementary strands, which allows for unwinding and separation.

Each strand serves as a template for the ordering of new nucleotides (according to the base-pairing rules) into a new complementary strand.

Question 2

Describe the semiconservative model of DNA replication predicted by Watson and Crick

Answer 2

When a DNA double helix replicates, that each of the two daughter DNA molecules would have one old strand, from the parental molecule and one newly made strand.

Question 3

It was the research of _________ and __________ that conclusively demonstrated that DNA replicates in a semiconservative manner

Answer 3

Matthew Meselson and Franklin Stahl

Question 4

Describe the conservative model of DNA replication

Answer 4

Predicted the two complementary parental strands somehow came back together after replication

Question 5

Describe the dispersion model of DNA replication

Answer 5

All four strands combining into a mixture of old and new DNA strands

Question 6

Meselson and Stahl worked with bacteria. What did researchers do to show that the semi-conservative mechanism of replication is similar in prokaryotes and eukaryotes?

Answer 6

Labeled individual nucleotides with fluorescent labels. Followed entire strands of eukaryotic DNA under the microscope as it replicated.

Results: 
Observed faint (hybrid) and dark (parent) fluorescing strands of labeled DNA even within one chromosome. Therefore, eukaryotes do follow a similar mechanism