BIOL 0280 Lecture Notes - Lecture 21: Consensus Sequence, Repressor, Dna-Binding Domain

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7 Nov 2016

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Rna polymerase binds to dna at promoter sequences. Sigma subunit mediates promoter recognition: coli has 7 sigma factors. Sigma 70 recognizes most e. coli promoters (housekeeping) Sigma 32 recognizes heat shock promoters (different consensus sequence) *ability to distinguish genes into housekeeping vs. heat shock. Others: modulation of cellular n levels, stationary phase genes, chemotaxis genes, ec functions. Affinity of rna polymerase is also regulated by binding proteins to/near promoters. Repressors: impede access of rna polymerase to dna. In negative regulation, can either be on promoter in absence of ligand or off promoter in absence. Repressor binding site is operator because it interferes. Encodes genes required for use of lactose as a c source. Tetramerizes and binds o3 and o1 together or o1 and o2 --> looping of either p or lacz. Binds to the operator (repressor binding site) in the absence of allolactose (inducer) --> transcription is repressed.

Related Questions

1 DNA sequences found in introns provide [A] amino acid sequence information.

[B] regulatory information.
[C] no known useful information.

[D] structure for the gene.
[E] alternative DNA splicing possibilities.

3. The TATA box is a(n)
[A] sequence close to the promoter region of many genes.
[B] square-shaped sequence.
[C] enhancer consensus sequence.
[D] activator sequence necessary for proper translation.
[E] None of the above

5. Regarding genes and gene expression, which of the following is not a difference between prokaryotes and eukaryotes
[A] Eukaryotic DNA does not contain a TATA box close to the initiation site as does prokaryotic DNA.

[B] In eukaryotes, RNA polymerase requires

'transcription factors'or initiation.

[C] Prokaryotic genes are often grouped together in

operons.

[D] In eukaryotes, the regulation of several genes at once requires common control elements in each of the genes.
[E] There is a diversity of eukaryotic polymerases that is reflected in the diversity of eukaryotic promoters.

10) In eukaryotic cells, a repressor

[A] is made of DNA.
[B] binds to the enhancer region to block transcription. [

C] is located both upstream and downstream from the promoter.
[D] binds to the operator to block RNA polymerase.

[E] binds to a silencer to reduce transcription rates.

Coordinated regulation of genes in eukaryotic cells [A] is the result of positioning the same regulatory sequence in front of each gene.
[B] results from all of those genes being under the control of one promoter.

[C] occurs because related genes all have the same

operons.
[D] occurs because enhancers cause DNA to bend.

BIOL 0280 Lecture Notes - Lecture 21: Consensus Sequence, Repressor, Dna-Binding Domain

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