Gene Expression and Regulatory Mechanisms Quiz

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What prevents an mRNA from existing in the cell forever and therefore being translated forever?

Methylation of the mRNA

Inhibition by microRNAs

Binding to histones

Degradation by ribonucleases (correct)

How can a microRNA stop translation of a specific mRNA, but not all mRNAs in the cell?

By base pairing with the specific mRNA's 3' UTR (correct)

By interacting with the general transcription factors

By binding to the mRNA's promoter region

By altering the mRNA's 5' UTR

What are the advantages or disadvantages for a eukaryote to regulate the amount or activity of a protein in a cell via transcriptional control vs. post-translational control?

Transcriptional control allows for long-term regulation, while post-translational control provides rapid response. (correct)

Post-translational control affects only specific proteins, while transcriptional control affects all proteins.

Post-translational control allows for long-term regulation, while transcriptional control provides rapid response.

Transcriptional control affects only specific proteins, while post-translational control affects all proteins.

In eukaryotes, why must transcription be complete before translation begins?

Eukaryotic mRNA is exported from the nucleus only after transcription is finished Signup and view all the answers

If a strain of E. coli has a mutation in the operator of the trp operon that prevents binding by a repressor, will the operon be transcribed in the presence of tryptophan?

Yes, it will be transcribed Signup and view all the answers

If a strain of E. coli has a mutation in the operator of the trp operon, resulting in the repressor binding all the time even in the absence of tryptophan, what will happen?

The operon will never be transcribed Signup and view all the answers

If a strain of E. coli has a mutation so that no repressor protein is made, will transcription occur in the presence of lactose if glucose levels are low?

Yes, transcription will occur Signup and view all the answers

What is the function of a microRNA in stopping translation of a specific mRNA?

Binding to the 5’ UTR of the mRNA to prevent ribosome binding Signup and view all the answers

What is the role of an operator in the regulation of gene expression?

Inhibits the binding of a repressor protein Signup and view all the answers

What is the primary function of an enhancer in gene regulation?

Enhances the transcription of specific genes in a tissue-specific or signal-dependent manner Signup and view all the answers

In eukaryotes, why must transcription be complete before translation begins?

The mRNA and ribosomes are physically separated in eukaryotes Signup and view all the answers

If a strain of E. coli has a mutation in the operator of the trp operon that results in the repressor binding all the time even in the absence of tryptophan, what will happen?

The trp operon will not be transcribed in the presence of tryptophan and absent of tryptophan Signup and view all the answers

Explain why alternative splicing can never change the order of exons in an mRNA transcript.

Exons are already in the correct order in the pre-mRNA and cannot be rearranged Signup and view all the answers

What is the difference between a general transcription factor and a specific transcription factor?

General transcription factors are required for the transcription of all genes, while specific transcription factors are only required for certain genes Signup and view all the answers

What prevents an mRNA from existing in the cell forever and therefore being translated forever?

Degradation by ribonucleases Signup and view all the answers

How can a microRNA stop translation of a specific mRNA, but not all mRNAs in the cell?

Base pairing between microRNA and specific mRNA Signup and view all the answers

What is the role of an operator in the regulation of gene expression?

It is a DNA sequence that a repressor protein binds to Signup and view all the answers

In eukaryotes, why must transcription be complete before translation begins?

To enable export of the mRNA from the nucleus to the cytoplasm Signup and view all the answers

If a strain of E. coli has a mutation in the operator of the trp operon that prevents binding by a repressor, will the operon be transcribed in the presence of tryptophan?

Yes, it will be transcribed Signup and view all the answers

If a strain of E. coli has a mutation in the operator of the trp operon that results in the repressor binding all the time even in the absence of tryptophan, explain what will happen in the presence and absence of tryptophan.

The operon will not be transcribed in the presence of tryptophan and in the absence of tryptophan Signup and view all the answers

Explain why alternative splicing can never change the order of exons in an mRNA transcript.

The order of exons is determined by the DNA sequence and cannot be altered Signup and view all the answers

Gene Expression and Regulatory Mechanisms Quiz

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Questions and Answers

What prevents an mRNA from existing in the cell forever and therefore being translated forever?

How can a microRNA stop translation of a specific mRNA, but not all mRNAs in the cell?

What are the advantages or disadvantages for a eukaryote to regulate the amount or activity of a protein in a cell via transcriptional control vs. post-translational control?

In eukaryotes, why must transcription be complete before translation begins?

If a strain of E. coli has a mutation in the operator of the trp operon that prevents binding by a repressor, will the operon be transcribed in the presence of tryptophan?

If a strain of E. coli has a mutation in the operator of the trp operon, resulting in the repressor binding all the time even in the absence of tryptophan, what will happen?

If a strain of E. coli has a mutation so that no repressor protein is made, will transcription occur in the presence of lactose if glucose levels are low?

What is the function of a microRNA in stopping translation of a specific mRNA?

What is the role of an operator in the regulation of gene expression?

What is the primary function of an enhancer in gene regulation?

In eukaryotes, why must transcription be complete before translation begins?

If a strain of E. coli has a mutation in the operator of the trp operon that results in the repressor binding all the time even in the absence of tryptophan, what will happen?

Explain why alternative splicing can never change the order of exons in an mRNA transcript.

What is the difference between a general transcription factor and a specific transcription factor?

What prevents an mRNA from existing in the cell forever and therefore being translated forever?

How can a microRNA stop translation of a specific mRNA, but not all mRNAs in the cell?

What is the role of an operator in the regulation of gene expression?

In eukaryotes, why must transcription be complete before translation begins?

If a strain of E. coli has a mutation in the operator of the trp operon that prevents binding by a repressor, will the operon be transcribed in the presence of tryptophan?

If a strain of E. coli has a mutation in the operator of the trp operon that results in the repressor binding all the time even in the absence of tryptophan, explain what will happen in the presence and absence of tryptophan.

Explain why alternative splicing can never change the order of exons in an mRNA transcript.

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