Biology 1002B Study Guide - Midterm Guide: Lac Repressor, Small Nuclear Rna, Signal Recognition Particle

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turquoiseferret307

16 May 2016

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14. 1 regulation of gene expression in prokaryotic cells. Operon is a cluster of prokaryotic genes and the dna sequences involved in their regulation. Operator a short segment in the dna that is a binding sequence for a regulatory protein: controls the operation of genes next to it. Gene that is separate from the operon encodes the regulatory protein. Repressor reduces the likelihood that genes will be transcribed when bound to the dna. Activator increases the likelihood that genes will be transcribed when bound to the dna. Many operons are controlled by more than one regulatory mechanism and a number of the repressors and activators control more than one operon. Each operon is transcribed as a unit from the promoter into a single mrna which resultantly contains codes for several proteins. Transcription unit is the cluster of genes transcribed into a single mrna.

Related Questions

1.) What type of control best describes the lac operon when it is regulated by allolactose? Explain the features of this type of regulation using the lac operon as an example.

2.) What is positive gene regulation?

a) when an activator protein binds to the operator of a gene to turn expression off

b) when a repressor protein binds to the operator of a gene to turn expression off

c) when an activator protein binds to the operator of a gene to turn expression on

d) when a repressor protein binds to the operator of a gene to turn expression on

e) when a protein binds to DNA to change gene expression

3.) In the lactose operon of E. coli, what is the function of each of the following genes or sites: a) regulator, b) operator, c) promoter, d) structural gene Z and e) structural gene Y?

a) regulator gene

b) operator

c) promoter

d) structural gene Z

e) structural gene Y

4.) In a negative, repressible regulatory mechanism, transcription of the structural gene(s) occurs in

a) the presence of the co-repressor, but not in its absence.

b) the absence of the co-repressor, but not in its presence.

c) the presence of the inducer, but not in its absence.

d) the absence of the inducer but not in its presence.

e) the absence or presence of the co-repressor.

What are answers and can you explain them to me?

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 Study Guide - Midterm Guide: Lac Repressor, Small Nuclear Rna, Signal Recognition Particle

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