Question

State the role of DNA ligase in biotechnology.

Answer 1

DNA ligase is defined as an enzyme that belongs to the ligase class of enzyme classification. The most important function of DNA ligase is to ligate the DNA. DNA ligase can ligate and join the various types of DNA such as single-stranded DNA, double-stranded DNA, and recombinant DNA molecules.

Complete Answer:
- There are many different types of DNA ligases and each DNA Ligase has their action and need on different DNA molecules. A DNA molecule is made up of nucleotide units. Each nucleotide unit is composed of a ribose sugar, nitrogen base, and phosphate group.
- The four types of nitrogen bases that are present are adenine, guanine, thymine, and cytosine. Out of these four, the adenine and guanine are termed as the purines. While the other two are termed as pyrimidines i.e. thymine and cytosine. Generally, purines get bonded with the pyrimidines via hydrogen bonds (Adenine pairs with thymine and guanine pairs with cytosine).
- Nucleotides are attached and connected to form two long strands of DNA which then form a structure called a double helix. Two nucleotides are connected to each other by presence of a phosphodiester bond.
- In recombinant DNA technology, generally, DNA is cleaved and broken with the help of restriction enzymes. Restriction enzymes are defined as the endonucleases that cleave phosphodiester bonds within DNA to form DNA with a sticky end or blunt end.
- The restriction enzymes are target and tissue specific. Restriction enzymes observe a specific sequence of nucleotides and produce a double-stranded cut DNA.
- The function of DNA ligase is controlling DNA integrity by joining breaks in the phosphodiester bonds of DNA that occur during replication and recombination.

Note: DNA ligases are only capable of forming phosphodiester bonds in order to join two nucleotides. DNA ligases cannot form hydrogen bonds or it can ligate or join nitrogen bases.