Bio1334 Genetics - Molecular Genetics - Control Of Gene Expression (Lectures Six And Seven)
Demonstrate an overview of the principles of control of gene expression in eukaryotes Demonstrate an outline understanding of transcriptional control in eukaryotes Demonstrate appreciation of differences in gene expression in bacteria and control of gene expression in bacteria
Questions and Answers
- 1.
Which of the following is the correct term for transgenics?
- A.
Genes between species
- B.
More than one gene
- C.
Two different alleles
Correct Answer
A. Genes between speciesExplanation
Transgenics refers to the process of transferring genes between different species. This involves the introduction of genetic material from one organism into another, resulting in an organism that carries genes from both species. Therefore, the correct term for transgenics is "genes between species".Rate this question:
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- 2.
Which of the following inhibits RNA polymerase II?
- A.
α-amanitin
- B.
β-amanitin
- C.
α-polymerase
- D.
β-polymerase
Correct Answer
A. α-amanitinExplanation
α-amanitin is a potent inhibitor of RNA polymerase II, which is responsible for transcribing mRNA in eukaryotic cells. It binds to the active site of RNA polymerase II and prevents the enzyme from synthesizing RNA. This inhibition disrupts the process of gene expression and ultimately leads to cell death. β-amanitin, on the other hand, inhibits RNA polymerase II in bacteria, not eukaryotes. α-polymerase and β-polymerase are not known inhibitors of RNA polymerase II.Rate this question:
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- 3.
Name one of the Cis-acting regulatory regions.
Correct Answer
Enhancer
Enhancers
An enhancer
The enhancers
TATA box
The TATA box
Promoter
The promoters
The enhancerExplanation
The correct answer is enhancer. Cis-acting regulatory regions are DNA sequences that regulate the expression of genes located on the same DNA molecule. Enhancers are one type of cis-acting regulatory regions that can increase the transcription of genes by binding to specific transcription factors and promoting the assembly of the transcriptional machinery. They can be located upstream, downstream, or even within the gene they regulate. Enhancers can act over long distances and can influence the expression of multiple genes.Rate this question:
- 4.
Which of the following is the role of trans-acting proteins?
- A.
Bind to promoter and enhancer to control transcription from the gene
- B.
Bind to promoter to initiate transcription
- C.
Bind to promoter and enhancer to control translation from the gene
Correct Answer
A. Bind to promoter and enhancer to control transcription from the geneExplanation
Trans-acting proteins play a crucial role in gene regulation by binding to both the promoter and enhancer regions of a gene. This binding allows them to control the process of transcription, which is the synthesis of RNA from DNA. By interacting with these regulatory regions, trans-acting proteins can either enhance or repress the transcription of a gene, thereby influencing the expression of specific traits or functions. Their ability to bind to both the promoter and enhancer regions enables them to coordinate and fine-tune the transcriptional activity of genes in response to various cellular signals and environmental cues.Rate this question:
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- 5.
Fill in the blank:Transcription begins at the _______________, found within the promoter region.
Correct Answer
Initiation siteExplanation
The initiation site is where transcription begins within the promoter region. It is the specific location on the DNA where RNA polymerase binds and starts the process of transcribing the DNA into RNA. This site serves as a starting point for the assembly of the transcription complex and the subsequent synthesis of RNA molecules.Rate this question:
- 6.
Complete this sentence:_________ proteins bound to enhancers interact with the basal transcription complex.
Correct Answer
N/A - 7.
How does the structure of chromatin aid eukaryotic gene regulation?
- A.
By providing a "brake" on runaway basal transcription
- B.
Its tight packaging does not allow all genes to be expressed
- C.
Providing the perfect shape for basal transcription
Correct Answer
A. By providing a "brake" on runaway basal transcriptionExplanation
The structure of chromatin aids eukaryotic gene regulation by providing a "brake" on runaway basal transcription. This means that the tight packaging of chromatin prevents all genes from being expressed at once, allowing for more precise control over gene expression. This regulation is essential for maintaining the proper functioning of cells and ensuring that genes are only expressed when needed.Rate this question:
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- 8.
Complete the following sentence:Core histone proteins can also be covalently modified on their ___________________.
Correct Answer
N-terminal tails
N terminal tails
N-terminal tail
N terminal tailExplanation
The correct answer is N-terminal tails, N terminal tails, N-terminal tail, N terminal tail. The N-terminal tails of core histone proteins can undergo covalent modifications. These modifications, such as acetylation, methylation, phosphorylation, and ubiquitination, can affect the structure and function of chromatin, leading to changes in gene expression and various cellular processes.Rate this question:
- 9.
Complete the following sentence:In bacterial cells, genes of related function are often clustered into ____________.
Correct Answer
OperonsExplanation
In bacterial cells, genes of related function are often clustered into operons. Operons are functional units of DNA that consist of multiple genes that are transcribed together as a single mRNA molecule. This allows for coordinated regulation and expression of genes involved in a specific biological process or pathway. The genes within an operon are typically under the control of a single promoter region and are transcribed as a polycistronic mRNA, which means that multiple genes are translated from the same mRNA molecule. Operons are commonly found in prokaryotes and are essential for efficient gene regulation and expression in bacterial cells.Rate this question:
- 10.
True or False?An operon of a bacterial cell (cluster of related genes) has one promoter, thus all genes in an operon are transcribed together.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
In a bacterial operon, all the genes are transcribed together as they are controlled by a single promoter. The promoter region is responsible for initiating the transcription process by binding to RNA polymerase. Once the RNA polymerase is bound to the promoter, it transcribes all the genes present in the operon as a single mRNA molecule. This allows for coordinated regulation of gene expression, as all the genes within the operon are transcribed simultaneously and can be regulated as a unit. Therefore, the statement "An operon of a bacterial cell has one promoter, thus all genes in an operon are transcribed together" is true.Rate this question:
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- 11.
What is the function of Lac repressor in bacterial gene expression?
- A.
It blocks transcription of the lac operon in the absence of lactose
- B.
It activates transcription of the lac operon in the absence of lactose
- C.
It blocks transcription of the lac operon in the presence of lactose
- D.
It activates transcription of the lac operon in the presence of lactose
Correct Answer
A. It blocks transcription of the lac operon in the absence of lactoseExplanation
The Lac repressor is a protein that binds to the operator region of the lac operon in the absence of lactose. This binding prevents RNA polymerase from binding to the promoter and initiating transcription of the lac operon genes. Therefore, the Lac repressor blocks transcription of the lac operon in the absence of lactose.Rate this question:
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- 12.
True or False:Single pre-mRNAs can produce multiple products through alternative splicing.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Alternative splicing is a process in which different combinations of exons are joined together during mRNA processing, resulting in the production of multiple mRNA isoforms from a single pre-mRNA. This allows for the generation of different protein products from the same gene. Therefore, the statement "Single pre-mRNAs can produce multiple products through alternative splicing" is true.Rate this question:
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- 13.
What happens during alternative splicing of pre-mRNAs?
- A.
Exons are targeted for removal in different combinations
- B.
Introns are targeted for removal in different combinations
- C.
Specific exons are removed
- D.
Specific introns are removed
Correct Answer
A. Exons are targeted for removal in different combinationsExplanation
During alternative splicing of pre-mRNAs, exons are targeted for removal in different combinations. This process allows for the production of multiple mRNA transcripts from a single gene by selectively removing certain exons and joining the remaining exons together. This alternative splicing mechanism contributes to the diversity of proteins that can be generated from a limited number of genes, as different combinations of exons can result in different protein isoforms with distinct functions or properties.Rate this question:
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- 14.
Within gene sequences, introns can occur in:
- A.
The 5′ untranslated region (UTR), and the 3′ UTR
- B.
The 5′ UTR, the protein coding region, and the 3′ UTR
- C.
The coding region
- D.
The promoter, the 5′ UTR, the protein coding region, and the 3′ UTR
Correct Answer
A. The 5′ untranslated region (UTR), and the 3′ UTRExplanation
Introns are non-coding regions within a gene sequence that are transcribed into RNA but are not translated into protein. The 5′ untranslated region (UTR) and the 3′ UTR are both regions that occur before and after the protein coding region. Therefore, introns can occur in these regions, as mentioned in the correct answer. The coding region, on the other hand, consists of exons, which are the coding sequences that are eventually translated into protein. The promoter is not a part of the gene sequence itself but is a region that controls the initiation of gene transcription. Therefore, introns do not occur in the promoter region.Rate this question:
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- 15.
Check the options below that can control mRNA stability and mRNA translation.
- A.
UTRs (untranslated regions)
- B.
Double stranded RNAs
- C.
Single stranded RNAs
- D.
SnRNAs
Correct Answer(s)
A. UTRs (untranslated regions)
B. Double stranded RNAsExplanation
UTRs (untranslated regions) are segments of mRNA that do not code for proteins but play a crucial role in controlling mRNA stability and translation. They contain regulatory elements that can influence the binding of proteins and other molecules involved in mRNA degradation and translation. Double stranded RNAs can also control mRNA stability and translation by triggering RNA interference, a process where small RNA molecules bind to mRNA and prevent its translation. Single stranded RNAs and snRNAs, on the other hand, are not directly involved in controlling mRNA stability and translation.Rate this question:
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- 16.
Fill in the blank:Injecting double stranded RNA reduces expression of specific genes by reducing levels of mRNA. This is known as RNA ___________ and is sequence specific.
Correct Answer(s)
InterferenceExplanation
Injecting double stranded RNA into a cell leads to a process called RNA interference. This process specifically targets and reduces the expression of certain genes by decreasing the levels of messenger RNA (mRNA). RNA interference is a sequence-specific mechanism, meaning it can selectively silence genes with complementary sequences to the injected double stranded RNA.Rate this question:
- 17.
Which form of small RNAs can also control gene expression?
Correct Answer(s)
Micro
Micro RNA
Micro RNAS
miRNA
miRNAsExplanation
MicroRNAs (miRNAs) are a form of small RNAs that can control gene expression. They are short RNA molecules that bind to messenger RNA (mRNA), preventing it from being translated into protein or marking it for degradation. This regulation of gene expression by miRNAs plays a crucial role in various biological processes, including development, cell differentiation, and disease progression. Therefore, all the options provided (Micro, Micro RNA, Micro RNAS, miRNA, miRNAs) can control gene expression through the action of miRNAs.Rate this question:
- 18.
Name the protein that binds to miRNA and mRNA in gene expression.
Correct Answer(s)
ArgonauteExplanation
Argonaute is the protein that binds to miRNA and mRNA in gene expression. It plays a crucial role in the RNA interference pathway, where it guides the miRNA to the target mRNA, leading to the degradation of the mRNA or inhibition of its translation. Argonaute proteins are essential for regulating gene expression and are found in various organisms, including humans. They are known for their role in post-transcriptional gene silencing and are key players in many biological processes, including development, immune response, and disease.Rate this question:
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