Question

1. Why DNA replication happens in continuous and discontinuous manner?

2. Write and explain about degenerate and nested primers.

3. What are the limitations in choosing a plant species for your cloning experiment?

4. Write briefly about glyceraldehyde-3-phosphate dehydrogenase (GAPDH) enzyme and origin of GAPDG gene.

Answer 1

1.   Because direction of DNA replication is 5’ to 3’ direction.

DNA is a double helical structure in which both stands are arranged in antiparallel manner. one stand have two hands one is 5’ phosphate end and another is 3’ OH ends.

The replication of DNA occurs in bidirectional manner in which replication fork moves in both of the directions. As a result of replication of DNA strands two different stands was produced one is continuous stand known as leading strand and other is discontinuous stand called as lagging strand of replicated DNA. Discontinuous lagging strand produces okazaki fragments of DNA.

So we can say that fix orientation of template strand of DNA and particular direction of synthesis of new strand by incorporation of deoxyribonucleotides is responsible for the formation of continuous and discontinuous synthesis of DNA.

Moment of replication occurs in both of the direction the double helical structure become unwind or open so that primer can attach and produce replicated DNA strand. In the continuous strand, direction of opening of double strand is the direction of synthesis, but in the discontinuous both are in opposite manner which leads to formation of DNA okazaki fragments.