Chapter 11

Chapter 11 - d. additional factors i. Post replication...

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d. additional factors i. Post replication repair 1. mismatch repair 2. nucleotide excision repair When all these mechanisms are taken together, the error rate drops to 1: 1e12 III. Termination of replication in E. coli A. Specific sequences in the DNA act as signals: TER signals multiple DNA sequences B. Function of the Tus protein, Ter utilization substance a. To prevent the replication fork from plowing through the Ter signal physically functions as a road block b. This is well-conserved between prokaryotes and eukaryotes 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.) Chapter 11 Transcription
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I. Introduction Of the all DNA in the cell, only some is transcribed. A. Transcription is the process of synthesizing a RNA polymer from individual NTPs, have 2 carbon hydroxyls, in a DNA directed manner. 1. The first step in gene expression B. The transfer of the genetic information encoded in DNA through the intermediate molecule, RNA, must occur with great fidelity. Life cannot support unfaithful interpretation of the genetic information. II. The mechanics of transcription are conserved throughout the evolution; however, differences RNA synthesis do exist between prokaryotes and eukaryotes. A. Transcription in prokaryotes 1. Prokaryotes: no organized nucleus chromosomes and ribosome are freely floating 2. dsDNA ssRNA Protein B. Transcription in eukaryotes 1. Eukaryotes: distinct nucleus 2. Txn. in nucleus, translation (protein synthesis) in cytoplasm the two rxns. are compartmentalized 3. Eukaryotic mRNA (messenger RNA) is processed prior to translation. 1. Includes a series of chemical modifications which tells the cell, it is mature RNA III. Types of RNA in cells A. rRNA (ribosomal RNA): integral structural component of the ribosome. Makes up ~66% of the ribosome mass 1. Expressed at extremely high levels B. mRNA (messenger RNA): Sequence that directs protein synthesis in the ribosome
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1. only account for 1/3 of RNA in the cell C. tRNA (transfer RNA): structurally compact RNAs that deliver amino acids to the ribosome during translation 1. structurally compact Note: RNA does not contain thymine. RNA contains uracil. –OH on 2’ carbon of ribose
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Chapter 11 - d. additional factors i. Post replication...

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