22_Lieb_Prokar_Transcription_notes

22_Lieb_Prokar_Transcription_notes - Biology 202 - Lieb...

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Biology 202 - Lieb Prokaryotic Gene Regulation Page 1 of 3 Introduction In both prokaryotes and eukaryotes, transcription proceeds in stages called Initiation , Elongation , and Termination. You should be able to describe what each stage involves, and what protein factors (of the ones we mention) are required for each step. In E. coli , initiation of transcription requires the sigma subunit of RNA polymerase. Initiation in eukaryotes is more complex, and involves many transcription factors (next lecture). Termination depends on both proteins and DNA sequences, and perhaps DNA structures that arise from the single-stranded DNA created during transcription. I. E. coli genetic nomenclature Bacteria have a single circular "chromosome", about 4-5 Mb. They may also carry one or more plasmids – small, circular, extrachromosomal DNA molecules. In E. coli , genes are named with three lowercase letters and one uppercase, all in italics. The three letters usually reflect something about the function of the gene. The protein encoded by the gene is written in roman (not italics), with the first letter also capitalized. Sometimes a protein has a common name, and that is used instead. Some examples: Gene Protein Function recA RecA recombination metF MetF methionine synthesis lacZ beta-galactosidase lactose metabolism II. Regulation of transcription initiation Some terms you will need to know: constitutive = genes expressed at a constant level at all times. inducible
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This note was uploaded on 03/02/2009 for the course BIOL 201 taught by Professor Mitchell during the Spring '07 term at UNC.

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22_Lieb_Prokar_Transcription_notes - Biology 202 - Lieb...

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