Chapter 04

Chapter 04 - Chapter 4 The Transmission of DNA at Cell...

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Unformatted text preview: Chapter 4 The Transmission of DNA at Cell Division (Mitosis and meiosis) •Overview •DNA replication is prerequisite to cell division. •DNA is replicated by using each strand as template for synthesis of the complementary strand. –one strand is synthesized continuously, the other discontinuously –all nucleotides are added at the 3’ end of the growing strand •Replicated chromosomes are partitioned to nuclei of daughter cells in mitosis. •Meiosis distributes replicated chromosomes to haploid daughter cells in two nuclear and cell divisions. •DNA replication •Occurs in the S phase of the cell cycle •Replication is semiconservative, with each DNA strand serving as template for synthesis of the complementary strand •DNA synthesis occurs in replicons consisting of an origin of replication and two diverging replication forks (bidirectional) •Each replication fork contains a complex of enzymes, including DNA polymerase •Polymerization of DNA •DNA polymerization requires the following: –dATP, dGTP, dCTP, dTTP (collectively dNTPs) –single-stranded template –primer with free 3’ hydroxyl to accept incoming nucleotide –DNA polymerase, Mg +2 •Accessory enzymes –primosome containing RNA primase –helicase to unwind DNA –gyrase to relax supercoils formed by unwinding •Leading and lagging strands...
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This note was uploaded on 09/21/2009 for the course MCB 5896 taught by Professor Zhang during the Spring '08 term at UConn.

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Chapter 04 - Chapter 4 The Transmission of DNA at Cell...

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