BIOL-UA 21 Lecture Notes - Lecture 13: Trp Operon, Catabolite Activator Protein, Rho Factor

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purplelocust18

11 Nov 2016

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Lecture 13: prokaryotic transcription: the genome is the same in muscle, neurons etc, but interpretation of it is different, regulation of gene expression: Expression: the process by which the information from a gene is used to make a product. Regulation: regulation of when/where/ and how much of a gene product is made from a given gene: transcription of dna into rna. Rna is synthesized 5" to 3" by rna polymerase. Downstream of +1 is marked by + nucleotides, and upstream are labelled negatively. Promoter has sequences important in localizing the rna polymerase upstream of the gene: e. coli rna polymerase: Polymerase binds to promoter in duplex dna and forms the closed complex. It opens the dna to form a transcription bubble (open complex). It can catalyze rna synthesis but cannot nd a promoter. The basal (general) transcription factors indicate where the rna polymerase should initiate transcription (sigma factor).

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.

Promoter fine mapping analysis is used to determine where the promoter starts and ends in a gene by deleting regions of DNA adjacent to and within the gene. You have a putative gene which you subject to promoter fine mapping analysis. You observe that transcriptional activity is still maintained when deletion from the 5' end reaches nucleotide +53, but is lost upon further deletion past +53. Activity is also maintained when deletion from the 3' end reaches nucleotide +83, but is lost upon further deletion past +83. Please speculate what gene family this putative gene belongs to and state which RNA polymerase is used for its transcription

1. What is the term when the product of a biochemical pathway inhibits the activity of the first enzyme of a pathway?

		feedback inhibition.
		activator inhibition.
		diffusional regulation.
		enzyme activation.

2. Through control of gene expression, prokaryotes respond to changing __________ conditions.

		internal
		protein
		environmental
		genetic

3. A protein that negatively regulates transcription by binding to the operator is known as the

		operon
		repressor
		activator
		inducer

4. During attenutation, when tryptophan levels are high, the ________ stem-loop forms and transcription ________ the trpL gene.

		1-2, ends just past
		3-4, ends just past
		1-2, continues beyond
		3-4, continues beyond

5. The process of turning on the expression of a gene in response to a substance in the environment is called:

		constituation.
		repression.
		induction.
		catabolism.

6. What is a function of some specific transcription factors?

		to bind to the promoter region of the gene to facilitate the proper alignment of the RNA polymerase
		to bind to the centromere to induce meiosis
		to bind to enhancer regions to help regulate gene transcription
		to bind to the operator to recruit sigma factor

7. How does exposing an E.coli cell to glucose affect the regulation of the lac operon via CAP?

		cAMP binds to CAP and transcription is increased.
		cAMP binds to CAP and transcription is decreased.
		cAMP does not bind to CAP and transcription is increased.
		cAMP does not bind to CAP and transcription is decreased.

8. The lac repressor protein works when mutations in the repressor gene and structural genes are:

		in cis or in trans.
		in trans only.
		in cis only.
		in both prokaryotes and eukaryotes.

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BIOL-UA 21 Lecture Notes - Lecture 13: Trp Operon, Catabolite Activator Protein, Rho Factor

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