Question

DNA synthesis during replication is –
A) Discontinuous
B) Continuous
C) Semi-discontinuous
D) None of the above

Answer 1

Hint: 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.

Complete answer:
DNA replication is the biological process of production of two identical replicas of DNA from one original molecule of DNA. DNA is made up of two complementary strands forming a double helix. During replication, these strands get separated, each strand of the DNA molecule serves as a template for the production of its counterpart, due to this property, replication is said to be a semiconservative process. As a result of semi-conservative replication, the newly formed molecules will have a strand of original DNA strand as well as a newly synthesized strand.
DNA replication occurs in three steps
>Initiation- the DNA molecule unwinds in the presence of DNA gyrase and DNA helicase. Single cell binding proteins prevents the strands from rewinding. This causes the DNA molecule to form a Y shaped replication fork.
>Elongation- synthesis of new strands initiates at origin of replication due to action of primase and DNA polymerases. A continuous strand called leading strand is synthesized along the 3’-5’ strand while discontinuous strand which is called lagging strand is formed along the strand having configuration 5’-3’ called Okazaki fragments.
>Termination- the single cell binding proteins separate and the okazaki fragments join together by ligase enzyme. 2 molecules are formed from a single molecule of DNA.

Thus, the correct answer is-”C”. semi-discontinuous.

Note:DNA polymerases have the ability to polymerise DNA in 5’-3’ direction. DNA molecules have 2 strands, one in 3’-5’ configuration while the other in 5’-3’ configuration. While replication, one strand is continuously synthesized while the other is synthesized in a discontinuous manner. DNA replication occurs in a semi-discontinuous manner and it is a semi conservative process. One continuous and one discontinuous strand.