BIO SCI 98 Study Guide - Midterm Guide: Bzip Domain, Homeobox, Operon
19 Jun 2018
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Lecture 1
Regulated gene expression underlies adaptation to changing environmental conditions,
development & differentiation
Transcription: the production of a complementary copy of RNA on DNA:
(1) protein coding = mRNA
(2) non-protein coding: rRNAs, tRNAs, splicing factors)
RNA polymerase binds to the promoter to initiate transcription.
Transcription factors help RNA polymerase recognize promoters
Transcription consists of initiation, elongation and termination steps
Bacteria: Sigma factors bind to the core RNA polymerase to direct it to promoters. Other
factors may stimulate or repress bacterial transcription.
Eukaryotes: transcription is more complex than in bacteria:
more transcription factors and 3 RNA polymerases)
mRNA must be capped, spliced, polyadenylated & exported from nucleus in order to be
translated by ribosomes
Lecture 2
Regulation of transcription initiation allows control before energy committed to expression by
production of un-used mRNAs.
-Control at transcriptional level à saves energy
-Control by degrading mRNA à rapid response
Gene expression controlled by transcription factors which bind to specific DNA sequences.
Transcription can be regulated by activators or repressors which are influenced by small
molecule effectors
In bacteria, genes for shared processes are organized into operons with transcription into a
polycistronic mRNA encoding more than one protein.
Regulatory proteins are usually dimers which bind to inverted repeats. TF structural motifs
include: helix-turn-helix, homeodomain, basic leucine zipper, basic helix hoop helix & zinc
fingers. Some TFs have multiple motifs.
Lecture 3
• Transcriptional control of bacterial operons
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Document Summary
Regulated gene expression underlies adaptation to changing environmental conditions, development & differentiation. Transcription: the production of a complementary copy of rna on dna: (1) protein coding = mrna (2) non-protein coding: rrnas, trnas, splicing factors) Rna polymerase binds to the promoter to initiate transcription. Transcription consists of initiation, elongation and termination steps. Bacteria: sigma factors bind to the core rna polymerase to direct it to promoters. Other factors may stimulate or repress bacterial transcription. Eukaryotes: transcription is more complex than in bacteria: more transcription factors and 3 rna polymerases) mrna must be capped, spliced, polyadenylated & exported from nucleus in order to be translated by ribosomes. Regulation of transcription initiation allows control before energy committed to expression by production of un-used mrnas. Control at transcriptional level saves energy. Control by degrading mrna rapid response. Gene expression controlled by transcription factors which bind to specific dna sequences.
