PCL477H1 Lecture Notes - Lecture 2: Reactive Oxygen Species, Glutathione Peroxidase, Dna Repair
14 Sep 2016
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Document Summary
Lecture 2-spontaneous dna damage and direct base repair. All biological macromolecules spontaneously decompose nucleic acids spontaneously decompose in solution. Rna is more vulnerable than dna to decomposition because the 2-hydroxyl group of ribose makes the phosphodiester bonds of rna molecules much more susceptible to hydrolysis, especially in the presence of divalent cations (ca2+, mg2+). Lost of 2"hydroxyl group makes the phosphodiester bond more stable. The presence of 2"oh group makes phosphodiester bond less stable. Therefore, rna is adequate typically for short-term storage of genetic information. Viruses that use rna as a genome, this carrier is short-lived and mutation prone. The ribose sugar of dna is patially reduced to 2"-deoxyribose: improved chemical stability. Makes the n-glycosidic bond (base-sugar) of dna more susceptible to hydrolysis than rna. Causing base spontaneously release from dna over time in solution as a function of ph, temp. , ionic strength and nucleic acid secondary structure.
