BIO 320 Lecture19_2009

BIO 320 Lecture19_2009 - BIO320CELLBIOLOGY...

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Lecture 19 (04/02/09) DNA Replication Mechanisms: pg 266-281 Base-Pairing underlies DNA replication and DNA repair. The DNA replication fork is asymmetrical. The high fidelity of DNA replication requires several proofreading mechanisms. Only DNA replication in the 5’-3’ direction allows efficient error correction. A special nucleotide polymerizing enzyme synthesizes short RNA primer molecules on the  lagging strand. Special proteins help to open up the DNA double helix in front of the replication fork. A sliding ring holds a moving DNA polymerase onto the DNA. The proteins at a replication fork cooperate to form a replication machine. DNA topoisomerases prevent DNA tangling during replication. DNA replication is similar in eukaryotes and bacteria. The Initiation and Completion of DNA Replication in Chromosomes: pg 281-293 DNA synthesis begins at replication origins. Bacterial chromosomes have a single origin of DNA replication. Eukaryotic chromosomes  contain multiple origins of replication. In eukaryotes DNA replication takes place during only one part of the cell cycle. Different regions on the same chromosome replicate at distinct times in S phase Well-defined DNA sequences serve as replication origins in a simple eukaryote, the  budding yeast. A large multisubunit complex binds to eukaryotic origins of replication. The mammalian DNA sequences that specify the initiation of replication have been difficult  to identify. New nucleosomes are assembled behind the replication fork. Telomerase replicates the ends of chromosomes. An Overview of the Cell Cycle: pg 1054-1055 Lecture Outline I. Introduction     A. Self-duplication is a fundamental property of life. B. DNA duplicates by a process called replication. C.
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This note was uploaded on 04/12/2009 for the course BIO 50160 taught by Professor O' halloran during the Spring '09 term at University of Texas.

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BIO 320 Lecture19_2009 - BIO320CELLBIOLOGY...

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