AP BIOLOGY

Detailed explanation-1: -DNA ligases connect DNA fragments by catalyzing the formation of a phosphodiester bond between a 3′-OH and a 5′-phosphate group at a single-strand break in double-stranded DNA (Lehman 1974). In cells, DNA ligases are essential for joining Okazaki fragments during replication, and in the last step of DNA repair process.

Detailed explanation-2: -DNA ligase is a DNA-joining enzyme. If two pieces of DNA have matching ends, ligase can link them to form a single, unbroken molecule of DNA. In DNA cloning, restriction enzymes and DNA ligase are used to insert genes and other pieces of DNA into plasmids.

Detailed explanation-3: -Restriction enzymes and DNA ligases represent the cutting and joining functions in DNA manipulation. All other enzymes involved in genetic engineering fall under the broad category of enzymes known as DNA modifying enzymes. These enzymes are involved in the degradation, synthesis and alteration of the nucleic acids.

Detailed explanation-4: -Ligase, an enzyme that uses ATP to form bonds, is used in recombinant DNA cloning to join restriction endonuclease fragments that have annealed. The ligase commonly used is T4 DNA ligase, which was first isolated from E. coli that were infected with the lytic bacteriophage T4.

Detailed explanation-5: -These include ligases, nucleases, methyltransferases, DNA repair proteins, recombinases and more.