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L9 + L10 - Procaryotic RNA transcription & regulation

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malra16's version from 2018-01-09 16:04

Section 1

Question Answer
The helix-turn-helix motifis a protein folding patter, and can be observed in a variety of prokaryotic DNA-binding proteins. They can also be observed in proteins, that bind DNA as dimers.
Which mechanisms is used by bacteria to regulate their metabolic pathways?Control of the expression of genes, control of enzyme activities (Allosteric and inhibitor), alternative splicing (Altered enzymes) and control of enzymes through covalent modification.
Beta Galactosidase in E.coli is present in varying conc. depending on the carbon source. It is a product of an operon. Produces galactose and glucose by hydrolyzing B-1,4-linked disaccharide lactose. Creates B-1,6 disaccharide allolactose.
High levels of a lampda repressor...means that the repressor will bind to all three operator sites. The repressor bound to OR1, blocks access by the promotor to the rest of the operon, repressing transcription.
Which 3 things does a operon usually consist of?A promotr, an operator and structural genes
Inverted repeats are often DNA bindings site of what?Proteins
Transcription can be accelerated by..Proteins, which bind specific DNA sequences and RNA polymerase
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Section 2

Question Answer
E.Coli promoters..may be associated with different transcription efficiencies.
for most genes include variants of consensus sequences.
They specify the start sites for transcription on DNA template.
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Section 3

Question Answer
What is a p-protein?A protein involved in transcription termination.
p-proteins of E.coli..acts as a RNA-DNA helicase
Leader sequences in amino acid operons...Attenuation is achieved through abundance of one amino acid residue in the leader peptide sequence. Leader sequences are found on the 5' end of the operon.
The cAMP-CAP complex..protects the 87 to 49 sequence of the lac operon from nuclease digestion. When it binds to the operon, it contacts RNA polymerase.
What enzyme carries out transcription?RNA polymerase
What are the 3 stages of transcription?Initiation, elongation and termination
Where can termination occur?At GC rich hairpin areas or at the rho complex.
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