The bacterial chromosome is less than 20 kb long

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Unformatted text preview: ene, increasing their local concentra/on and therefore the probability that they will interact with more promoter ­proximal TFs, or TFIID, or the en/re, poised ini/a/on complex. Ready to roll- RNA polymerase will not take all these factors with it! 5/23/11 Bacteria don’t use enhancers. Why not? a. b. c. d. e. The concentra/on of ac/vators is too high. The bacterial chromosome is not flexible Its easy to find promoters in bacteria ­ they don’t need them The genes are too crowded to be regulated by something 20kb away. The bacterial chromosome is less than 20 kb long. Transcrip/on factors are include “domains” ­ func/onally dis/nct regions of a single polypep/de that essen/ally fold and work independently. We’ll draw them like this: Domain 1 And some/mes… Domain 2 Domain 3 5/23/11 This diagram shows the primary structure of a prototypical TAF ­ the domains might be in any order ­ they’re all just sort of /ed together loosely by the primary structure of the protein. Signal Sensing Domain Not always there… see “stress” example DNA Binding Domain Determines site ­specificity Trans ­ac/va/on Domain This is the real “ac/on” ­ aaracts pol I...
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