Biochemistry 2280A Chapter Notes - Chapter 16: Hemoglobin, Globin, Homologous Chromosome
24 Apr 2018
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In a multicellular organism, permanent changes in the dna called mutations can upset the organism"s extremely complex and nely tuned development and physiology. Most dna damage is only temporary, because it is immediately corrected by processes collectively called dna repair. Dna damage occurs continually in cells: dna is continually undergoing thermal collisions with other molecules, often resulting in major chemical changes in the dna. Common sources of damage: depurination can remove guanine (or adenine) from dna. Dna phosphodiester backbone but instead removes a purine base from a nucleotide: the spontaneous loss of an amino group (deamination) from a cytosine in dna to produce the base uracil. 5: dna can also be altered by replication itself. The replication machinery that copies the dna can quite rarely incorporate an incorrect nucleotide that it fails to correct via proofreading. Cells possess a variety of mechanisms for repairing dna.
