#4 Filled in Skeleton Notes

#4 Filled in Skeleton Notes - Skeleton 5 notes Hogan, Chem...

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Skeleton 5 notes Hogan, Chem 130 Lecture notes DNA Replication “It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material”. -James Watson, 1953. I. DNA Replication A. DNA is replicated by enzymes known as: ___________________________ 1. Replication is semiconservative 2. Meselson – Stahl experiment B. Initiation of replication 1. DNA polymerase requires an origin of replication : 2. reaction details C. Replication occurs at replication forks (“eyes”, “bubbles”, theta structures) 1. unidirectional replication: 1
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Skeleton 5 notes Hogan, Chem 130 Lecture notes 2. bidirectional replication: D. Replication is semi-discontinuous 1. DNA synthesis is unidirectional a. Leading strand: b. Lagging strand c. Okazaki fragments E. DNA synthesis requires a short RNA primer (RNA primase) 1. Number of RNA primers is strand-specific a. Leading strand: b. Lagging strand c. Excision and replacement 2
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Skeleton 5 notes Hogan, Chem 130 Lecture notes II. DNA polymerases A. Arthur Kornberg discovered and enzyme that synthesizes DNA (1957) 1. DNA polymerase I (DNA pol I): a. b. c. 2. Exonuclease activity a. 5’ 3’ b. 3’ 5’ c. cellular function of exonuclease activity: d. cellular role of DNA pol I B. DNA polymerase III (DNA pol III) directed synthesis 1. pol III holoenzyme catalyzes the synthesis of leading and lagging strands 2. The components of the replisome: a. number of pol III enzymes: b. gyrase c. DnaB protein (helicase) 3
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Skeleton 5 notes Hogan, Chem 130 Lecture notes d. Primosome: e. DNA ligase: C. Fidelity of replication If a single subunit of pol I is capable of replicating DNA by itself , why does the bacterial cell require a large multi-protein complex composed of >20 polypeptides to replicate the chromosome? DNA replication must occur with great fidelity. Incorrect expression of the information encoded in the genetic material leads to major problems for an organism. 1. Natural error rates in bacteria, i.e. number of mistakes/ 1000 bp replicated: _____ 2. Sources of fidelity: a. dNTP concentrations: b. 2 step polymerase reaction: c. proofreading by Pol I and Pol III d. additional factors III. Termination of replication in E. coli A. Specific sequences in the DNA act as signals:______________________ B. Function of the Tus protein Final thoughts We have focused our discussion of replication on prokaryotes; however, it is important to note that eukaryotic replication is very similar, but far more complex (i.e. the number of proteins involved in the replisome, etc.) 4
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Skeleton 5 notes Hogan, Chem 130 Lecture notes Transcription I. Introduction A. Transcription is the process of synthesizing a RNA polymer from individual NTPs in a DNA directed manner. B. The transfer of the genetic information encoded in DNA through the
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This note was uploaded on 03/22/2009 for the course CHEM 430 taught by Professor Redinbo during the Spring '07 term at UNC.

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#4 Filled in Skeleton Notes - Skeleton 5 notes Hogan, Chem...

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