Lecture.12.Fall.2013

4 billion bp of dna if an error rate is 1 in 1

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Unformatted text preview: f Replication Genetic information must be copied accurately • Even a low rate of error in replicating DNA could be catastrophic for an organism • Example: • Single celled human zygote - 6.4 billion bp of DNA • If an error rate is 1 in 1 million bp, then 6400 mistakes would be made every time a cell was divided. • There are trillions of cells in the human body Genetic information must be copied quickly • ACCURATE AND RAPID DNA must be copied very rapidly • E. coli genome is 4.6 million bp. • If the rate of replication were ~1000 nt/minute you could almost finish replicating one genome in 3 days Genetic information must be copied quickly • In fact, E. coli: • • Replicates its DNA at a rate of 1000 nt/second • • Can divide in 20 minutes Has an error rate less than 1 in a billion nts. How? BELOW SLIDES Three basic models: TO ACCOMPLISH REPLICATION CUT AND PASTE CONSERVED MOLEC EACH TIME CONSERVED ABOUT HALF Meselson and Stahl’s experiment • Used equilibrium d...
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