What does ligase do

Only DNA fragments that have matching, complementary ends can be joined by ligation. Ligases join fragments of DNA together by catalysing the formation of bonds between neighbouring nucleotides. Cells naturally carry out ligation during DNA replication , when the Okazaki fragments are joined together. Cells also use ligation to repair DNA that has been damaged, either by normal cell metabolism or by environmental factors, such as UV light or radiation.

Up to 1 million breaks can occur in the DNA of a single human cell each day. For DNA ligation to occur in the lab, the reaction mixture must contain: complementary DNA fragments, a ligase buffer , and a source of energy. The energy for this reaction normally comes from a chemical called ATP adenosine triphosphate. DNA is prepared for ligation by being cut into fragments with restriction enzymes.

Ligation can join together fragments of DNA from different sources. Ligation is often used for DNA cloning. Let us understand the ligase mechanism with the help of DNA Ligase as an example.

Definition: DNA ligases are the ligases that join or bind the two DNA fragments also known as Okazaki fragments by forming a phosphodiester bond. The most widely utilized ligase in a science laboratory is the DNA ligase. Generally, these ligases are named according to the substrate or the macromolecules involved in the reaction; for, e. Ligase enzymes are synonymous with synthetase enzymes. However, synthetase enzymes are often confused with synthase enzymes. On the other hand, synthase enzymes are the ones that catalyze the synthesis of biological macromolecules without the hydrolysis of nucleoside triphosphates.

There are six classes of enzymes and ligases are one of them. The other classes of enzymes include oxidoreductases, transferases, hydrolases, isomerases, and lyases. Ligase and lyase are closely related classes of enzymes.

However, Ligase and lyase are different classes of enzymes. Based on the molecular bond catalyzed by the ligase enzyme, ligase can be classified into six subclasses see Table 2. Try to answer the quiz below to check what you have learned so far about ligases.

Genes are expressed through the process of protein synthesis. This elaborate tutorial provides an in-depth review of the different steps of the biological production of protein starting from the gene up to the process of secretion.

Also included are topics on DNA replication during interphase of the cell cycle, DNA mutation and repair mechanisms, gene pool, modification, and diseases Read More. This tutorial presents the benefits and the possible adverse eventualities of genetic engineering. Know more about this topic in this tutorial to be able to articulate the advantages and disadvantages of artificially manipulating genes Skip to content Main Navigation Search.

Dictionary Articles Tutorials Biology Forum. Table of Contents. Ligases are classified into six subclasses: 1 EC 6. Synonym: synthetase. To Email. Time is Up! Genetic Information and Protein Synthesis Genes are expressed through the process of protein synthesis. Related Articles