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Three excision repair pathways exist to repair single stranded DNA damage: Nucleotide excision repair (NER), base excision repair (BER), and DNA mismatch repair (MMR). While the BER pathway can recognize specific non-bulky lesions in DNA, it can correct only damaged bases that are removed by specific glycosylases. Similarly, the MMR pathway ...
A DNA polymerase is a member of a family of enzymes that catalyze the synthesis of DNA molecules from nucleoside triphosphates, the molecular precursors of DNA. These enzymes are essential for DNA replication and usually work in groups to create two identical DNA duplexes from a single original DNA duplex.
DNA is defined by containing 2'-deoxy-ribose nucleic acid while RNA is defined by containing ribose nucleic acid. [1] In some occasions, DNA and RNA may contain some minor bases. Methylated forms of the major bases are most common in DNA. In viral DNA, some bases may be hydroxymethylated or glucosylated.
Depiction of the restriction enzyme (endonuclease) HindIII cleaving a double-stranded DNA molecule at a valid restriction site (5'–A|AGCTT–3').. In biochemistry, a nuclease (also archaically known as nucleodepolymerase or polynucleotidase) is an enzyme capable of cleaving the phosphodiester bonds that link nucleotides together to form nucleic acids.
This leads to an issue due to the fact that DNA polymerase is only able to add to the 3' end of the DNA strand. The 3'-5' action of DNA polymerase along the parent strand leaves a short single-stranded DNA (ssDNA) region at the 3' end of the parent strand when the Okazaki fragments have been repaired.
DNA damage recognition and repair – a certain DNA repair mechanism utilizes kinetic proofreading to discriminate damaged DNA. [8] Some DNA polymerases can also detect when they have added an incorrect base and are able to hydrolyze it immediately; in this case, the irreversible (energy-requiring) step is addition of the base.
DNA mismatch repair (MMR) is a system for recognizing and repairing erroneous insertion, deletion, and mis-incorporation of bases that can arise during DNA replication and recombination, as well as repairing some forms of DNA damage.
Pol β is the main human polymerase that catalyzes short-patch BER, with pol λ able to compensate in its absence. [8] These polymerases are members of the Pol X family and typically insert only a single nucleotide. In addition to polymerase activity, these enzymes have a lyase domain that removes the 5' dRP left behind by AP endonuclease cleavage.