BIO130H1 Lecture Notes - Lecture 9: Pyrimidine Dimer, Dna Mismatch Repair, Covalent Bond
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BIO130H1 Full Course Notes
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Mismatch repair: error occurs, mismatch reading proteins bind, the strand with the error is removed, repair dna synthesis. Dna can be damaged by: oxidation through metabolism of the cell, chemicals carcinogens and mutagens, radiation uv, x-ray and gamma rays, heat. The covalent bond should not be between bases, this is caused by uv light, in the example of a thymine dimer. A deaminated cytosine, and now we have uracil. Ap endonuclease cuts the backbone around where the u was taken off, through phosphodiesterase activity this will digest the sugar activity: ligase comes in and seals the nick. Nucleotide excision repair: this targets many nucleotides all at once. Rna can either encode a protein or function as rna. Opening up the helix supercoiling and torsional strain. 5 polypeptides making up rna polymerase quaternary structure. The dna and rna hybrid is held together by base pairing.
