BIO230H1 Lecture Notes - Lecture 3: Lambda Phage, Prophage, Repressor

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BIO230H1 Full Course Notes

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Competition between rna polymerase and repressor protein for promoter binding. Activator protein recruits rna polymerase to the promoter to activate transcription. Gene regulatory elements are typically close to the transcription start site of prokaryotic genes: but regulatory elements may also be found. Some regulatory elements are distant from the transcriptional start site and influence transcription. Dna looping: the ntrc protein is a transcriptional activator, dna looping allows ntrc to directly interact with rna polymerase to activate transcription from a distance. Positive and negative regulatory mechanisms work together to regulate lifestyles of bacteriophage lambda: two proteins repress each other"s synthesis. Bacteriophage lambda can exist as one of two states in bacteria: under favourable bacterial growth conditions dna polymerase can"t tell different between dna. Integration of lambda dna replicates along with host chromosome = Prophage pathway: when host cell is damaged = induction event. Synthesis of viral proteins needed for formation of new viruses.

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.

QUESTION 1

In the bacterial lac repressor, which of these occurs: (select all that apply)

		(a)In the presence of glucose and the absence of lactose, the repressor is actively produced.
		(b)The lac operon can be hyper-induced in the presence of low glucose by the 'cAMP binding protein' (CAMP).
		(c)In the presence of lactose and the absence of glucose the lac operon is repressed.
		(d)Allolactose is a byproduct of Î²-galactosidase, indicating high lactose when it builds up.

1.5 points

QUESTION 2

In eukaryotes the enhancer elements can be quite a distance upstream or downstream from the promoter, and transcriptional regulation is helped by protein:protein interactions.

True

False

1.5 points

QUESTION 3

The prokaryotic promoter contains a TATA box that is at -10bp upstream from the transcriptional start site.

True

False

1.5 points

QUESTION 4

During the addition of the poly A tail which of these occurs:(select all that apply)

		(a)The transcript is synthesized beyond the poly A site (AAUAAA).
		(b)The mRNA contains a 5â cap.
		(c)The transcript is cleaved 35nt downstream from the poly A site.
		(d)An enzyme complex containing an exonuclease and polyadenylate polymerase cleaves nearby the AAUAA site.
		(e)100-300 Aâs are added to the 5â end.

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BIO230H1 Lecture Notes - Lecture 3: Lambda Phage, Prophage, Repressor

BIO230H1 Full Course Notes

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