Biochemistry 2280A Lecture 16: Bio chem topic 16
19 Dec 2017
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Basic mechanism of dna repair: dna damage = any unintended physical or chemical change in dna, any unintended change, the cell views that dna damage is always bad. Cell recoginizes damage: get rid of damage, then use other strand as a template to fill in the gap, there is now a nick, we need dna ligase to seal this. Causes of dna damage: copying mistakes: dna polymerase makes an error once every ~107 nucleotides. Insertion: the top strand is longer than bottom, has an extra base. Deletion: the bottom is longer because the top strand is missing a base. The bottom strand is not a problem. But the top strand is a template but it is not the right template. Once it has incorporated a new wrong nucleotide it is a mutation. This position could be very important and mess up the cell. Causes of dna damage: depurination: loss of a or g base.
