Molecular Biology and Genetics Quiz

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Questions and Answers

Which enzyme is used to join DNA fragments together in molecular cloning?

Ligase

In prokaryotes, transcription and translation occur simultaneously due to the absence of which cellular component?

Nucleus

In a strain of E. coli with a mutation in the trp operon operator preventing repressor binding, will the operon be transcribed in the presence of tryptophan?

Yes

Why is the lac operon off by default in E. coli?

Binding of repressor Signup and view all the answers

How are histone modifications used to alter gene transcription?

By influencing chromatin structure and accessibility Signup and view all the answers

What is the role of a general transcription factor in gene expression?

Recruitment of RNA polymerase Signup and view all the answers

Why can alternative splicing never change the order of exons in an mRNA transcript?

Primary RNA transcript structure restricts exon order changes Signup and view all the answers

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

Degradation by nucleases Signup and view all the answers

How can a microRNA stop translation of a specific mRNA without affecting all mRNAs in the cell?

By base-pairing with the target mRNA Signup and view all the answers

What are the advantages of eukaryotic cells regulating protein production via post-translational control?

Rapid response to environmental changes Signup and view all the answers

What is the difference between a purine and a pyrimidine?

Presence of a double ring structure Signup and view all the answers

What is the function of the Kozak sequence in eukaryotic mRNA translation?

Initiation of translation Signup and view all the answers

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

It helps RNA polymerase recognize the promoter sequence Signup and view all the answers

During mRNA synthesis, where does the energy come from to create bonds between nucleotides?

Phosphodiester bonds are formed using the energy from the hydrolysis of pyrophosphate Signup and view all the answers

What is the importance of the 2’, 3’, and 5’ carbons of RNA (and/or DNA)?

They contribute to the stability of the RNA/DNA structure Signup and view all the answers

What is the role of tRNA and how are tRNAs 'charged'?

tRNA carries specific amino acids to the ribosome; charging occurs through the attachment of amino acids by aminoacyl-tRNA synthetases Signup and view all the answers

Which process allows a primary RNA transcript to make multiple versions of a protein?

Alternative splicing Signup and view all the answers

What can increase or decrease transcription of a gene according to chromatin structure?

Histone modification Signup and view all the answers

Are the noncoding portions of mature mRNAs (untranslated regions) considered part of exons?

No Signup and view all the answers

Which statement is true regarding methylation of CpG islands in eukaryotes like humans?

Methylation can lead to gene silencing Signup and view all the answers

Is alternative splicing another name for polycistronic transcripts?

No Signup and view all the answers

Where are microRNAs produced by transcription?

Nucleus Signup and view all the answers

Neuropeptide Y is not expressed in liver cells. What could be a possible reason for this?

Differential gene regulation Signup and view all the answers

Which process involves separating DNA fragments based on their size and charge?

Gel electrophoresis Signup and view all the answers

In which direction does PCR synthesize DNA?

5' to 3' Signup and view all the answers

What is the impact of a mutation in the operator of the trp operon in E. coli?

It can impact the transcription of the operon in the presence or absence of tryptophan Signup and view all the answers

What is the function of DNA ligase in molecular cloning?

It joins DNA fragments together Signup and view all the answers

What is the role of histone modifications in eukaryotes?

They alter gene transcription Signup and view all the answers

How does mRNA in eukaryotes prevent continuous translation?

It is eventually degraded Signup and view all the answers

What is the function of microRNA in gene expression?

It can specifically stop translation of a target mRNA without affecting all mRNAs in the cell Signup and view all the answers

How do eukaryotes regulate protein production?

Through transcriptional or post-translational control Signup and view all the answers

What is the function of gel electrophoresis in molecular biology?

It separates DNA fragments based on size and charge Signup and view all the answers

What is the role of the 2’, 3’, and 5’ carbons in RNA and/or DNA?

2’ and 3’ carbons are involved in forming phosphodiester bonds, while the 5’ carbon is the site of attachment for phosphate groups. Signup and view all the answers

Why is it overkill to use four nucleotides per codon in the genetic code?

Using four nucleotides per codon would lead to redundancy and would not significantly increase the number of amino acids that can be coded for. Signup and view all the answers

Where in the eukaryotic cell do transcription, mRNA processing, and translation occur?

Transcription and mRNA processing occur in the nucleus, while translation occurs in the cytoplasm. Signup and view all the answers

What is the enzymatic activity of the enzyme used in PCR?

Polymerase activity to synthesize new DNA strands. Signup and view all the answers

What is the process by which a primary RNA transcript can be used to make multiple versions of a protein called?

Splicing Signup and view all the answers

Which of the following can increase or decrease transcription of a gene according to chromatin structure?

Histone modification Signup and view all the answers

Are the noncoding portions of mature mRNAs (untranslated regions) considered part of exons?

No, they are part of introns Signup and view all the answers

Which statement is true regarding methylation of CpG islands in eukaryotes like humans?

Methylation can have context-dependent effects on gene expression Signup and view all the answers

Is alternative splicing another name for polycistronic transcripts?

No, they are distinct processes Signup and view all the answers

Where are microRNAs produced by transcription?

Nucleus Signup and view all the answers

Neuropeptide Y is not expressed in liver cells. What could be a possible reason for this?

Epigenetic regulation specific to liver cells Signup and view all the answers

What is the term for the structures that allow for vision in humans and are only found in retinal cells?

Cones and rods Signup and view all the answers

Which enzyme is used to join DNA fragments together in molecular cloning?

DNA polymerase Signup and view all the answers

In which direction does PCR synthesize DNA?

5' to 3' Signup and view all the answers

What can specifically stop translation of a target mRNA without affecting all mRNAs in the cell?

MicroRNA Signup and view all the answers

Which process separates DNA fragments based on size and charge?

Gel electrophoresis Signup and view all the answers

What is the impact of a mutation in the operator of the trp operon in E. coli?

It affects transcription of the operon in the presence of tryptophan Signup and view all the answers

What is the function of histone modifications in eukaryotes?

Alter gene transcription Signup and view all the answers

What is the role of alternative splicing in mRNA transcripts?

It affects translation efficiency Signup and view all the answers

What prevents continuous translation of mRNA in eukaryotes?

mRNA degradation Signup and view all the answers

How do eukaryotes regulate protein production?

Both transcriptional and post-translational control Signup and view all the answers

What is the function of recombinant DNA technology?

Inserting DNA from one species into another Signup and view all the answers

What is the impact of a mutation in the operator of the trp operon in E. coli in the presence of tryptophan?

It affects transcription of the operon Signup and view all the answers

What is the role of microRNA in gene expression?

Inhibiting translation Signup and view all the answers

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

It helps in the recognition of the promoter sequence Signup and view all the answers

During mRNA synthesis, where does the energy come from to create bonds between nucleotides?

Hydrolysis of pyrophosphate from incoming nucleoside triphosphates Signup and view all the answers

What is the importance of the 2’, 3’, and 5’ carbons of RNA (and/or DNA)?

They contribute to the stability of the RNA/DNA molecule Signup and view all the answers

What is the function of tRNA and how are tRNAs 'charged'?

tRNA carries specific amino acids to the ribosome; they are charged by the attachment of amino acids Signup and view all the answers

What prevents continuous translation of mRNA in eukaryotes?

Poly-A tail addition Signup and view all the answers

Which of the following can increase or decrease transcription of a gene according to chromatin structure?

Histone modification Signup and view all the answers

Are the noncoding portions of mature mRNAs (untranslated regions) considered part of exons?

No Signup and view all the answers

Which statement is true regarding methylation of CpG islands in eukaryotes like humans?

Methylation of CpG islands can lead to gene silencing Signup and view all the answers

Is alternative splicing another name for polycistronic transcripts?

No Signup and view all the answers

Where are microRNAs produced by transcription?

Nucleus Signup and view all the answers

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

Recognizing the promoter sequence Signup and view all the answers

What is the impact of a mutation in the operator of the trp operon in E. coli in the presence of tryptophan?

The operon will be transcribed Signup and view all the answers

Which enzyme is used in molecular cloning to join DNA fragments together?

DNA polymerase Signup and view all the answers

In which direction does PCR synthesize DNA?

5' to 3' Signup and view all the answers

What is the impact of a mutation in the operator of the trp operon in E. coli in the presence of tryptophan?

No impact on transcription Signup and view all the answers

What prevents continuous translation of mRNA in eukaryotes?

Degradation of mRNA Signup and view all the answers

What is the role of histone modifications in eukaryotes?

Activate gene transcription Signup and view all the answers

What is the function of microRNA in gene expression?

Stop translation of specific mRNA Signup and view all the answers

What allows eukaryotes to regulate protein production through transcriptional or post-translational control?

Transcription factors Signup and view all the answers

Which process separates DNA fragments based on size and charge?

Gel electrophoresis Signup and view all the answers

What is the function of recombinant DNA technology?

Insert DNA from one species into another Signup and view all the answers

What is the impact of a mutation in the operator of the trp operon in E. coli?

No impact on transcription Signup and view all the answers

What is the role of alternative splicing in mRNA transcripts?

Generate multiple protein isoforms Signup and view all the answers

What is the function of DNA ligase in molecular cloning?

Join DNA fragments together Signup and view all the answers

Study Notes

Molecular Biology Questions Summary

Recombinant DNA involves inserting DNA from one species into another, such as human DNA into bacteria.
DNA ligase is used in molecular cloning to join DNA fragments together.
Eukaryotes must wait until transcription is complete before beginning translation, unlike prokaryotes where they occur simultaneously.
A mutation in the operator of the trp operon in E. coli can impact the transcription of the operon in the presence or absence of tryptophan.
Histone modifications alter gene transcription in eukaryotes.
Alternative splicing cannot change the order of exons in an mRNA transcript.
mRNA in eukaryotes can be translated many times, but it is eventually degraded, preventing continuous translation.
MicroRNA can specifically stop translation of a target mRNA without affecting all mRNAs in the cell.
Eukaryotes can regulate protein production through transcriptional or post-translational control, with different advantages and disadvantages.
PCR synthesizes DNA in the 5' to 3' direction.
Gel electrophoresis separates DNA fragments based on size and charge.
Bacteria can replicate DNA containing human DNA due to the ability of bacteria to handle foreign DNA.

Molecular Biology Questions Summary

Recombinant DNA involves inserting DNA from one species into another, such as human DNA into bacteria.
DNA ligase is used in molecular cloning to join DNA fragments together.
Eukaryotes must wait until transcription is complete before beginning translation, unlike prokaryotes where they occur simultaneously.
A mutation in the operator of the trp operon in E. coli can impact the transcription of the operon in the presence or absence of tryptophan.
Histone modifications alter gene transcription in eukaryotes.
Alternative splicing cannot change the order of exons in an mRNA transcript.
mRNA in eukaryotes can be translated many times, but it is eventually degraded, preventing continuous translation.
MicroRNA can specifically stop translation of a target mRNA without affecting all mRNAs in the cell.
Eukaryotes can regulate protein production through transcriptional or post-translational control, with different advantages and disadvantages.
PCR synthesizes DNA in the 5' to 3' direction.
Gel electrophoresis separates DNA fragments based on size and charge.
Bacteria can replicate DNA containing human DNA due to the ability of bacteria to handle foreign DNA.

Molecular Biology Questions Summary

Recombinant DNA involves inserting DNA from one species into another, such as human DNA into bacteria.
DNA ligase is used in molecular cloning to join DNA fragments together.
Eukaryotes must wait until transcription is complete before beginning translation, unlike prokaryotes where they occur simultaneously.
A mutation in the operator of the trp operon in E. coli can impact the transcription of the operon in the presence or absence of tryptophan.
Histone modifications alter gene transcription in eukaryotes.
Alternative splicing cannot change the order of exons in an mRNA transcript.
mRNA in eukaryotes can be translated many times, but it is eventually degraded, preventing continuous translation.
MicroRNA can specifically stop translation of a target mRNA without affecting all mRNAs in the cell.
Eukaryotes can regulate protein production through transcriptional or post-translational control, with different advantages and disadvantages.
PCR synthesizes DNA in the 5' to 3' direction.
Gel electrophoresis separates DNA fragments based on size and charge.
Bacteria can replicate DNA containing human DNA due to the ability of bacteria to handle foreign DNA.

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