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Questions

Question 1

What is the term for the complete collection of RNA molecules in a cell, which includes protein-coding mRNAs, functional non-coding RNAs, and their various forms from processes like editing and splicing?

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Question 2

Which level of gene regulation is affected by how tightly DNA is packaged, which in turn influences how easily transcription machinery can access a gene?

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Question 3

In prokaryotic transcription, what is the term for a promoter that has a sequence closely matching the -10 and -35 consensus sequences, leading to high levels of transcription?

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Question 4

What is the name of the process where a transcription factor increases the rate of transcription from a promoter?

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Question 5

In eukaryotes, what is the function of the large protein complex called the mediator?

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Question 6

What is a polycistronic RNA, a feature often found in prokaryotic gene regulation?

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Question 7

In the lac operon of E. coli, what is the direct role of allolactose?

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Question 8

What is the state of the lac operon regulatory proteins (LacI repressor and CAP) when an E. coli cell is in an environment with high glucose and no lactose?

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Question 9

A 'super repressor' mutation in the lac operon, designated Is, results in a lac repressor that cannot bind to allolactose. What is the phenotypic consequence of this mutation?

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Question 10

In the lambda phage life cycle, the lambda repressor (λCI) can act as both an activator and a repressor. What does λCI repress?

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Question 11

What is the mechanism of transcriptional attenuation in the trp operon when tryptophan levels are low?

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Question 12

Why is ribosome-mediated transcription attenuation a mechanism of gene regulation that is unique to prokaryotes?

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Question 13

What would be the effect on the expression of the lac operon from a loss-of-function mutation in the gene for adenylate cyclase?

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Question 14

Considering the lac operon genotype I+, O+, Z+, Y+, would beta-galactosidase be expressed if the E. coli were grown in a medium with no glucose and no lactose?

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Question 15

Considering the lac operon genotype I+, O+, Z+, Y+, would beta-galactosidase be expressed if the E. coli were grown in a medium with high glucose and high lactose?

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Question 16

For the lac operon genotype I+, Oc, Z+, Y+ (a constitutive operator mutation), would beta-galactosidase be expressed if the E. coli were grown in a medium with high glucose and no lactose?

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Question 17

How does the negative autoregulation of the lambda repressor (λCI) work at high concentrations?

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Question 18

What is the term for a DNA element that is part of an operon and is specifically recognized by a repressor protein?

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Question 19

Which statement accurately describes the function of the structural genes in the lac operon?

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Question 20

What type of mutation is a change in the DNA of a gene's promoter that prevents a repressor from binding?

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Question 21

In the lambda phage, what triggers the switch from the lysogenic to the lytic cycle?

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Question 22

Which of the following describes the collection of proteins present in a cell, including those that have been modified post-translationally?

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Question 23

Which of the following is NOT listed as a level at which gene expression can be regulated in a cell?

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Question 24

What is the key difference in translation initiation that prevents eukaryotes from having polycistronic mRNAs like prokaryotes?

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Question 25

What is the role of the sigma factor in prokaryotic transcription initiation?

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Question 26

What is the level of transcription of the lac operon in an E. coli cell with the genotype I+, O+, Z+, Y+ when grown in a medium containing no glucose but high levels of lactose?

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Question 27

In a partial diploid E. coli with the genotype I- O+ Z+ / I+ O+ Z-, would beta-galactosidase (product of Z gene) be produced in the presence of lactose?

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Question 28

In a partial diploid E. coli with the genotype I+ Oc Z+ / I+ O+ Z-, would beta-galactosidase (product of Z gene) be produced in the absence of lactose?

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Question 29

The lac operon promoter (lacP) is described as a weak promoter. What does this imply about its sequence?

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Question 30

What is the primary role of the protein product of the lacY gene in E. coli?

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Question 31

What structural feature of the trp operon's leader RNA allows it to form a terminator hairpin?

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Question 32

What would be the likely effect of a mutation that changes the two tryptophan codons (UGG) in the trp operon leader sequence to two stop codons (UGA)?

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Question 33

The genes of the lac operon are transcribed into a single polycistronic RNA, but they are translated into separate proteins. How is this achieved in prokaryotes?

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Question 34

What is the function of the catabolite activator protein (CAP) in the regulation of the lac operon?

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Question 35

Which term describes a mutation in the lac operon's operator DNA that prevents the repressor from binding?

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Question 36

The lambda repressor (λCI) protein exhibits cooperative binding to its operator sites. What does this mean?

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Question 37

What is the primary difference between the lytic and lysogenic cycles of a bacteriophage like lambda?

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Question 38

Considering the lac operon genotype Is, O+, Z+, Y+, would beta-galactosidase be expressed if the E. coli were grown in a medium with no glucose and high lactose?

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Question 39

What type of molecule is the product of the lacI gene?

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Question 40

What is the function of the C-terminal domain of the lambda repressor (λCI) protein?

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Question 41

Which statement best describes a 'constitutive mutation' in the context of the lac operon?

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Question 42

How do eukaryotes typically achieve co-regulation of genes that are located on different chromosomes?

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Question 43

What is the integrated viral DNA sequence called during the lysogenic cycle of a bacteriophage?

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Question 44

In the trp operon attenuation system, what is the role of the 2-3 hairpin structure that can form in the leader RNA?

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Question 45

What happens to the lac operon when an E. coli cell is in an environment where both the lac repressor and the CAP activator can bind to their respective DNA sites?

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Question 46

What is the molecular signal that indicates low glucose levels to the lac operon's regulatory system?

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Question 47

Why is the lac repressor described as an allosteric protein?

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Question 48

What is the function of the promoter PR in the lambda phage genome?

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Question 49

In a partial diploid E. coli with the genotype Is O+ Z+ / I+ O+ Z-, would beta-galactosidase (product of Z gene) be produced in the presence of lactose?

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Question 50

If a mutation changed the tryptophan codons (UGG) in the trp leader sequence to cysteine codons (UGC), what would be the impact on the transcription of the trp operon?

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