BIOL 205 Chapter Notes - Chapter 8: Cyclic Adenosine Monophosphate, Repressor, Lac Operon

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6 Dec 2016

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Wwu: control of transcription is usually exerted at the step at which the process is initiated. The promoter region of a gene binds the enzyme rna polymerase and correctly orientates the enzyme to being its task of making an rna copy of that gene. The promoters of both bacterial and eukaryotic genes includes a transcriptional initiation site- where rna synthesis begins plus a sequence of approx 50 nucleotide pairs that extends upstream from the initiation site. This upstream site contains sites that are required for the rna polymerase to recognize the promoter although they do not bind to rna polymerase directly. Instead, these sequences contain recognition sites for proteins that associate with the active polymerase . These are called sigma factors for bacteria: nearly all genes- bacterial or eukaryotic- have regulatory dna sequences . Regulatory dna sequences are used to switch a gene on or off.

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.

5. Alpha amanitin is a drug that binds RNA polymerase andprevents it from functioning in the cell (this is the compound thatis found in poison mushrooms). The reason people die when theyconsume alpha amanitin is:

a) Alpha amanitin prevents gene expression from occurring in thecell

b) DNA replication is directly inhibited by alpha amantin

c) Alpha amanitin binds tightly to the messenger RNAs that aremade in the cell, preventing translation

d) Alpha amanitin binds to nuclear pores preventing thetransport of messenger RNA into the cytoplasm

6. In order for transcriptional initiation to begin in E. colithe following elements are needed:

a) an origin and RNA polymerase

b) initiator protein and a promoter

c) the sigma subunit of RNA polymerase and an RNA template

d) RNA polymerase and a promoter

e) helicase and primase

Questions 7 and 8. You are studying two species of closelyrelated snakes, one species lives in sandy desert area and has paletan skin and the species lives in a volcanic rock area and has darkbrown skin. You a sequence the DNA from each type of snake anddiscover a gene encoding a protein that transports pigment into theskin cells. The pigment transporter protein is responsible for skincolor. When you analyze the DNA coding sequence of the pigmenttransporter from each snake you find these two DNA sequences (hashmarks have been added to indicate the reading frame):

pale tan snake: GCG/TTG/GAC/TGC/ACC (DNA template strand)CGC/AAC/CTG/ACG/TGG (complementary strand) dark brown snake:ACG/TTG/GAC/TGC/ACC (DNA template strand) TGC/AAC/CTG/ACG/TGG(complementary strand)

7. From these sequences you conclude:

a) that the amino acid sequence of the pigment transporters forthe two proteins are almost identical

b) that the amino acid sequence of the pigment transporters forthe two proteins are very dissimilar

c) that the amino acid sequence of the pigment transporters forthe two proteins are identical

8. Since the skin color is different in each snake, you concludefrom the sequence data above that:

a) the genetic code in the skin cells in each of these snakes isdifferent

b) the DNA sequence encoding the entire gene for pigmenttransporters in these two snakes is different

c) that one of the codons in the gene for the pigmenttransporter in these two snakes is different

9. You are analyzing eukaryotic cells that have been exposed tothe radioactive uracil. In most cells the radioactive uracil isinitially localized in the nucleus and then moves from the nucleusto the cytoplasm. However, you observe that in some cells theradioactive molecules stay in the nucleus and never arrive in thecytoplasm. This is most likely a defect in:

a) the transcription of the DNA

b) the processing of the mRNA

c) the translation of the RNA

d) the labeling of the RNA

e) the replication of the DNA

10. Which of the following is true of both eukaryotic andbacterial transcription? (select all that are true)
a) Transcription factors must bind the promoter before RNApolymerase initiates transcription

b) Messenger RNAs must be spliced before translation begins inorder to produce the appropriate gene product

c) During transcription only one DNA strand is used as atemplate to make the messenger RNA

d) Termination of transcription occurs when the RNA polymerasetranscribes a hairpin structure in the RNA followed by a string ofU

erinporpoise384

Please help on these. Thank you!

Question 1

Which of the following is NOT a channel in the RNA polymeraseenzyme?

		RNA exit channel
		DNA entry channel
		DNA exit channel
		Nucleotide exit channel

Question 2

A promoter region upstream of a bacterial gene typically has thesequence TTGACA in the -35 position and TATAAT in the -10 position.If there was a 5 bp insertion at the -40 position, such thateverything downstream was shifted (ie: the "-35 element" is now atthe -30 from the transcription start site), which of the followingwill occur?

		Sigma protein will not bind and so no transcription willoccur.
		RNA polymerase will not bind and so no transcription willoccur.
		Sigma protein will bind to its target sequences and sotranscription will start 5bp downstream from the originaltranscription start site.
		Sigma protein will bind as usual and transcription will startappropriately at the transcription start site.

Question 3

A person has a mutation that prevents TFIIH from being produced.Which of the following outcomes will occur?

		No transcription because TFIID will not be able to bind.
		No transcription because the DNA strand will not be opened.
		Transcription will occur, but it will not be in the correctposition.
		Transcription will occur as usual.

Question 4

There are 4 rRNAs produced to make both subunits of theribosome. How many transcripts are required to produce these 4rRNAs?

		1
		2
		3
		4

Question 5

True or False: the 5' 7m-Gppp cap is attached to the start codonof the mRNA.

		True.
		False, the cap is attached to the 5'-untranslated region.
		False - the cap is attached to the 3'-untranslated region.
		False, the cap is attached to the polyA tail.

Question 6

During the splicing mechanism, which of the following joins twoexons together?

		A 2'OH attacks a 5' phosphate
		A 5' phosphate attacks a 2'OH
		A 3'OH attacks a 5' phosphate
		A 5' phosphate attacks a 3'OH Question 7 After their experiment in Neurospora, Beadle and Tatum concludedthat each single genes code for single enzymes. Do you agree withtheir statement, why or why not?

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BIOL 205 Chapter Notes - Chapter 8: Cyclic Adenosine Monophosphate, Repressor, Lac Operon

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