Biochemistry 2280A Lecture Notes - Lecture 29: Superoxide, Aciclovir, Ionizing Radiation
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12 Dec 2016
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Topic 20 continued: dna replication is semi-conservative, 5 different steps. We"ve got one strand that"s continuously adding to the strand. Numerous dna molecules 100 200nt long (in humans) on the lagging strand. The same polymerase makes all the okasaki fragments, just one at a time. Helicase unwinds the double helix dna polymerase follows, making. Sliding clamp protein helps dna polymerase stay associated with dn. New dna is always added to the 3" end (synthesis occurs 5" 3") It"s thought that 2 dna polymerases associate with each helicase: 4. Sometimes dna polymerase makes a mistake happens in 1 every 10^5 nucleotides (adds wrong nucleotide, adds extra nucleotide or skips a nucleotide) The enzyme: 3" 5" exonucleases removes the wrong nucleotides synthesis continues. Nuclease is an enzyme that breaks a nucleic acid strand. Exonucleases chews away starting at the end of the strand (exo means outside so it starts on the outside) Endonuclease cuts in the middle: 5.
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