Biology 1002B Chapter Notes - Chapter Cycle 7: Trp Operon, Essential Amino Acid, Operon

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19 Oct 2018

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An operon is a cluster of prokaryotic genes and the dna sequences involved in their regulation. The promoter is where the rna polymerase begins transcription. The operator is a short segment that is a binding sequence for a regulatory protein, which is another type of regulatory protein. A gene that is speerate from the operon encodes the regulatory protein. Some operons are controlled by a repressor, which when bound to the dna reduces the likelihood that the genes will be transcribed. An activator increases the likelihood that the genes will be transcribed. Mnay operons are controlled by more than one regulatory mechanism, and a number of repressors or activators control more than one operon. It is transcribed as a unit from the promoter into a single mrna, and this mrna codes for several proteins. The cluster of genes transcribed into a single mrna is called a transcription unit.

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.

A transcription factor G can act as either a repressor or an activator of operon M, depending on its conformational state.

In one conformational state, transcription factor G binds site 1 in the promoter of operon M. When bound to site 1, it is an activator of operon M transcription. Factor G cannot bind to site 1 if ligand X is bound to it.

When factor G binds to ligand X, factor G undergoes a conformational change such that it now binds site 2 in the promoter and represses operon M. Because of the way in which it acts, ligand X would be called a(n) ____.

Imagine that there is a mutation in the gene that encodes transcription factor G such that operon M is always transcribed.

Which of these mutations in the gene that encodes transcription factor G is consistent with that outcome?

Biology 1002B Chapter Notes - Chapter Cycle 7: Trp Operon, Essential Amino Acid, Operon

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