MBB 201 Study Guide - Midterm Guide: Dna Mismatch Repair, Dna Ligase, Pyrimidine Dimer
25 Sep 2017
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Dna damage: ionizing radiation, spontaneous mutations, errors during replication, A complex of mismatch repair proteins excise part of the newly synthesized strand only and resynthesize it, dna polymerase resynthesizes the strand and dna ligase seals it. Mismatches if uncorrected can lead to permanent mutations. Depurination bond breaks between pentose sugar and nitrogenous base could lead to a deletion of one or more nucleotides when dna replicates (a&g) Deamination could lead to alterations because amino group is lost from adenine, guanine, cytosine (makes uracil) Uv radiation from the sun can cause covalent linkages between two adjacent pyrimidines leading to thymine dimers. Many identical rna copies can be made from the same gene, so that lots of identical protein can be made-leading to successive amplification. Ribose sugar (2" is oh) -deoxyribose sugar (2" h) missing o-deoxy. Can fold up into a variety of shapes -can fold into a helix.
