Question

DNA ligase is an enzyme that catalyzes the
(a) splitting of DNA threads into small bits
(b) joining of fragments of DNA
(c) denaturation of DNA
(d) synthesis of DNA

Answer 1

Hint: DNA ligase is also called “molecular glue”. During DNA replication, It attaches the Okazaki fragments formed from the lagging strand during the replication of DNA. It is the enzymes that are commonly used in genetic engineering.

Complete answer:
DNA ligase is a biochemical catalyst which is used to join two strands of DNA mostly during the DNA synthesis.
During DNA replication, the lagging strand forms small fragments of DNA, due to the different direction in which it is replicated. These fragments are called Okazaki fragments. The lagging strand has the direction of 5’ to 3’ which is opposite to the polarity of the template strand. Okazaki fragments are joined by DNA ligase.

Additional Information:
1. DNA ligase is the equivalent of DNA Polymerase 1.
2. DNA Ligase helps in maintaining the integrity of the genome.
3. It helps in connecting two strands of DNA together by joining the phosphodiester. bonds of the backbone of DNA.
4. DNA ligase joins the ends of the DNA strand
5. Leading strand serves as a continuously synthesized strand.
6. Two different types of DNA combine with DNA ligase to form the recombinant DNA. After recombinant DNA is formed, this DNA is then transferred to the host cell.

So, the correct answer is ‘joining the fragments of DNA’.

Note:
DNA replication is a type of semi-replication. it was verified by Matthew Meselson and Franklin Stahl. DNA dependent DNA polymerase is the major component of the process of replication of DNA. Prokaryotes have a single origin of replication. Eukaryotes have more than a single origin of replication.