DNA ligase is the enzyme that joins the 3'-hydroxyl group of one nucleotide to the 5'-phosphate group of the next nucleotide, forming a phosphodiester bond and sealing the break in the DNA strand.

Homologous recombination is the primary mechanism for repairing double-strand breaks in DNA. It involves the use of a homologous DNA sequence as a template to repair the damaged region.

Photolyase is the enzyme that repairs thymine dimers, which are formed when adjacent thymine bases on the same DNA strand are covalently linked by ultraviolet light.

DNA glycosylases are enzymes that remove damaged bases from DNA by cleaving the N-glycosidic bond between the base and the sugar-phosphate backbone.

Mismatch repair is the mechanism responsible for correcting errors that occur during DNA replication. It involves the identification and removal of mismatched nucleotides from newly synthesized DNA strands.

DNA polymerases are enzymes that synthesize new DNA strands by adding nucleotides to the 3'-end of a growing DNA chain.

Exonucleases are enzymes that remove nucleotides from the ends of DNA strands. They play a role in proofreading newly synthesized DNA strands by removing mismatched nucleotides.

DNA ligases are enzymes that join the 3'-hydroxyl group of one nucleotide to the 5'-phosphate group of the next nucleotide, forming a phosphodiester bond and sealing the break in the DNA strand.

Nucleotide excision repair is the mechanism responsible for repairing bulky DNA adducts, which are large chemical modifications that can distort the DNA helix.

Endonucleases are enzymes that cleave DNA strands at specific sites. They play a role in DNA repair by removing damaged regions of DNA.

Single-strand break repair is the mechanism responsible for repairing single-strand breaks in DNA. It involves the use of DNA ligase to join the broken ends of the DNA strand.

Helicases are enzymes that unwind DNA strands by breaking the hydrogen bonds between complementary bases. They play a role in DNA repair by unwinding the DNA around the damaged region, allowing access to repair enzymes.

Homologous recombination is the primary mechanism for repairing DNA damage caused by ionizing radiation. It involves the use of a homologous DNA sequence as a template to repair the damaged region.

DNA topoisomerases are enzymes that relieve torsional stress in DNA by introducing or removing supercoils. They play a role in DNA repair by unwinding the DNA around the damaged region, allowing access to repair enzymes.

Base excision repair is the primary mechanism for repairing DNA damage caused by alkylating agents. It involves the removal of the damaged base and its replacement with a new base.