Question

Describe DNA synthesis in detail

Answer 1

Answer:

DNA synthesis is the biological process by which a deoxyribonucleic acid (DNA) molecule is created. In the cell, each of the two strands of the DNA molecule acts as a template for the synthesis of a complementary strand.

Answer 2

Answer:

The discovery of the double-helical nature of DNA by Watson & Crick explained how genetic information could be duplicated and passed on to succeeding generations. The strands of the double helix can separate and serve as templates for the synthesis of daughter strands. In conservative replication the two daughter strands would go to one daughter cell and the two parental strands would go to the other daughter cell. In semiconservative replication one parental and one daughter strand would go to each of the daughter cells.

Through experimentation it was determined that DNA replicates via a semiconservative mechanism. There are three possible mechanisms that can explain DNA's semiconservative replication.

(a) DNA synthesis starts at a specific place on a chromosome called an origin. In the first mechanism one daughter strand is initiated at an origin on one parental strand and the second is initiated at another origin on the opposite parental strand. Thus only one strand grows from each origin. Some viruses use this type of mechanism.

(b) In the second mechanism replication of both strands is initiated at one origin. The site at which the two strands are replicated is called the replication fork. Since the fork moves in one direction from the origin this type of replication is called unidirectional. Some types of bacteria use this type of mechanism.

(c) In the third mechanism two replication forks are initiated at the origin and as synthesis proceeds the two forks migrate away from one another. This type of replication is called bi-directional. Most organisms, including mammals, use bi-directional replication.