Question 1

An agent that would work well as an antibiotic against prokaryotic infection might target
A)the 50S large ribosomal subunit.
B)RNA polymerase II.
C)the 40S small ribosomal subunit.
D)DNA polymerase.
E)mitochondria.

Accepted Answer

The 50S large ribosomal subunit is part of the prokaryotic ribosome, which is different from eukaryotic ribosomes. Targeting it can inhibit protein synthesis in bacteria without affecting eukaryotic cells.

Question 2

Which of the following enzymes is associated with "transcription factories" in the nucleus?
A)RNA polymerase II
B)RNA polymerase I
C)DNA polymerase III
D)transcriptomes
E)reverse transcriptase

Accepted Answer

Transcription factories are nuclear sites where active transcription occurs, and RNA polymerase II is the enzyme primarily responsible for transcribing mRNA from DNA in eukaryotic cells.

Question 3

With respect to RNA processing,which of the following is false?
A)RNA processing leads to the production of alternative gene products.
B)Some introns are removed by spliceosomes.
C)Some introns are self-splicing.
D)Prokaryotic mRNAs are polyadenylated at the 3' end.
E)Chemical modification occurs in tRNA transcripts.

Accepted Answer

Prokaryotic mRNAs typically do not undergo polyadenylation at the 3' end, a process more common in eukaryotic mRNAs. Polyadenylation in eukaryotes aids in the stability and export of mRNA from the nucleus, among other functions.

Question 4

If you were designing a method to specifically inhibit prokaryotic transcription,but not eukaryotic transcription,interfering with which of the following would work best?
A)an intercalating agent
B)recognition of the prokaryotic promoter by RNA polymerase
C)DNase activity
D)RNA polymerase II activity
E)ribosomal binding to mRNA

Accepted Answer

Recognition of the prokaryotic promoter by RNA polymerase is specific to prokaryotes, as eukaryotic and prokaryotic promoters have different sequences and structures. Targeting this process would specifically inhibit prokaryotic transcription without affecting eukaryotic transcription.

Question 5

RNA polymerase II differs from RNA polymerase I and III by having
A)fewer amino acids at the N-terminus.
B)additional amino acids at the N-terminus.
C)fewer amino acids at the C-terminus.
D)additional amino acids at the C-terminus.
E)individual amino acids,but all three RNA polymerases are the same size.

Accepted Answer

RNA polymerase II is distinguished from RNA polymerase I and III by having additional amino acids at the C-terminus, known as the C-terminal domain (CTD). This domain is crucial for the processing of pre-mRNA into mature mRNA.

Question 6

In order to protect an mRNA from nuclease activity in the cytosol of a cell,a(n)________ is added to the 3' end during RNA processing.

Accepted Answer

The answer of In order to protect an mRNA from...

Question 7

With regard to RNA polymerase proofreading ability,which of the following is true?
A)RNA backtracking can remove noncomplementary nucleotides.
B)RNA and DNA polymerase proofreading are essentially identical.
C)There are specialized mRNA repair pathways that remove noncomplementary nucleotides.
D)No proofreading occurs.
E)A 3' → 5' exonuclease fixes all errors in mRNA.

Accepted Answer

RNA polymerase has a mechanism known as backtracking, which allows it to correct errors by removing noncomplementary nucleotides. This process is distinct from the proofreading mechanisms of DNA polymerase, which often involve a 3' → 5' exonuclease activity. There are no specialized mRNA repair pathways akin to DNA repair, and RNA polymerase does not have a dedicated 3' → 5' exonuclease for proofreading like DNA polymerase does.

Question 8

You have isolated a piece of DNA that you believe contains an interesting gene.Using a mix of RNA polymerase and ribonucleotides,you perform in vitro transcription.However,even though all of your controls work,no mRNA is created from your DNA fragment.Working backward,you note that your DNA preparation removed approximately 250 base pairs from the 5' end of the gene.The most likely explanation is that during DNA preparation
A)the termination signal was removed.
B)the RNA polymerase became inactivated.
C)the 5' methyl guanosine cap was removed.
D)the promoter was removed.
E)None of these explains the negative results.

Accepted Answer

The promoter region, typically located at the 5' end of a gene, is essential for the initiation of transcription by RNA polymerase. Removing approximately 250 base pairs from the 5' end likely removed the promoter, preventing RNA polymerase from binding and initiating transcription, thus explaining the lack of mRNA production.

Question 9

A mutation that results in the addition or deletion of a single nucleotide and therefore radically changes the amino acid sequence of the resulting polypeptide is known as a ________ mutation.

Accepted Answer

The answer of A mutation that results in the addition...

Question 10

In the absence of retroviruses,reverse transcription may occur in eukaryotes if which of the following is present?
A)promoters
B)transcription factors
C)retrotransposons
D)prions
E)None of these are correct.

Accepted Answer

Retrotransposons are genetic elements that can amplify themselves in a genome and are capable of reverse transcription, even in the absence of retroviruses.

Question 11

Which of the following most accurately describes the flow of information for retroviruses?
A)DNA → protein
B)RNA → protein
C)DNA → RNA → protein
D)protein → RNA → DNA → protein
E)RNA → DNA → RNA → protein

Accepted Answer

Retroviruses, such as HIV, use their RNA as a template to synthesize DNA through reverse transcription. This newly synthesized DNA is then integrated into the host's genome, from which it is transcribed into mRNA and subsequently translated into viral proteins. Thus, the flow of information is RNA → DNA → RNA → protein.

Question 12

The action of a new drug is unknown,so you test various aspects of eukaryotic cell processes looking for an effect.You notice that the survival of cells exposed to this drug is very low.Further analysis shows that some proteins and mRNAs are much longer than they should be.One hypothesis is that the drug interferes with
A)transcription termination signals.
B)spliceosome activity.
C)ribosomes.
D)nucleoli.
E)either transcription termination signals or spliceosome activity.

Accepted Answer

The observation that some proteins and mRNAs are much longer than they should be suggests that the drug interferes with processes that normally limit the length of these molecules. This could be due to interference with transcription termination signals, which would result in longer mRNAs by allowing transcription to continue past the normal stop point, or with spliceosome activity, which could result in longer proteins by including introns that are normally removed. Both scenarios would lead to the production of abnormally long proteins and mRNAs.

Question 13

A ________ is a complex of RNA and protein that serves to remove introns from pre-mRNA.

Accepted Answer

The answer of A ________ is a complex of RNA...

Question 14

In some organisms,a normal stop codon,UGA,encodes for the amino acid
A)leucine.
B)arginine.
C)isoleucine.
D)selenocysteine.
E)cysteine.

Accepted Answer

In some organisms, the UGA codon, which is normally a stop codon, can be redefined to encode the amino acid selenocysteine. This redefinition occurs in the presence of a specific sequence in the mRNA known as a selenocysteine insertion sequence (SECIS).

Question 15

A new antibiotic is able to bind the rho (ρ)factor associated with some transcription processes.As a result,this antibiotic would affect
A)initiation of transcription.
B)elongation of transcription.
C)binding of the RNA polymerase.
D)termination of all transcription.
E)termination of some transcription.

Accepted Answer

The rho (ρ) factor is specifically involved in the termination of some transcription processes in bacteria. When an antibiotic binds to the rho factor, it would specifically interfere with its ability to terminate transcription, affecting the termination of some, but not all, transcription processes.

Question 16

In some organisms,a special tRNA recognizes the UAG stop codon but incorporates the amino acid
A)methionine.
B)cysteine.
C)glycine.
D)pyrrolysine.
E)None of these.

Accepted Answer

In some archaea and bacteria, a special tRNA recognizes the UAG stop codon but incorporates the amino acid pyrrolysine, an unusual amino acid not found in most organisms.

Question 17

The coding regions of a eukaryotic gene are known as ________.

Accepted Answer

The answer of The coding regions of a eukaryotic gene...

Question 18

Transcription of ribosomal RNA is primarily the function of
A)primase.
B)RNA polymerase I.
C)RNA polymerase II.
D)RNA polymerase III.
E)mitochondrial RNA polymerase.

Accepted Answer

RNA polymerase I is primarily responsible for the transcription of ribosomal RNA (rRNA), which is a key component of the ribosome's structure and function in protein synthesis.

Question 19

Which of the following is associated with the production of multiple mRNAs from a single gene?
A)alternative splicing
B)spliceosome mutations
C)polycistronic organization
D)gene rearrangement
E)both spliceosome mutations and polycistronic organization

Accepted Answer

Alternative splicing allows a single gene to produce multiple mRNA variants, leading to the production of different proteins from the same gene. This process is a key mechanism for increasing the diversity of proteins that a cell can produce.

Question 20

The technique used to initially identity promoter sequences was
A)DNA fingerprinting.
B)chromosomal walking.
C)DNA footprinting.
D)chromatin immunoprecipitation assay.
E)RNA protection.

Accepted Answer

DNA footprinting is the technique used to identify the specific DNA sequences, such as promoter regions, that proteins bind to. This method involves treating a DNA-protein complex with a DNA-cleaving agent, removing the protein, and then analyzing the DNA fragments. The protected region (where the protein was bound) can be identified because it is not cleaved, hence "footprinting" the location of protein-DNA interactions.

Quiz 18: Gene Expression: Ithe Genetic Code and Transcription

An agent that would work well as an antibiotic against prokaryotic infection might target

Which of the following enzymes is associated with "transcription factories" in the nucleus?

With respect to RNA processing,which of the following is false?

If you were designing a method to specifically inhibit prokaryotic transcription,but not eukaryotic transcription,interfering with which of the following would work best?

RNA polymerase II differs from RNA polymerase I and III by having

In order to protect an mRNA from nuclease activity in the cytosol of a cell,a(n)________ is added to the 3' end during RNA processing.

With regard to RNA polymerase proofreading ability,which of the following is true?

A mutation that results in the addition or deletion of a single nucleotide and therefore radically changes the amino acid sequence of the resulting polypeptide is known as a ________ mutation.

In the absence of retroviruses,reverse transcription may occur in eukaryotes if which of the following is present?

Which of the following most accurately describes the flow of information for retroviruses?

A ________ is a complex of RNA and protein that serves to remove introns from pre-mRNA.

In some organisms,a normal stop codon,UGA,encodes for the amino acid

A new antibiotic is able to bind the rho (ρ) factor associated with some transcription processes.As a result,this antibiotic would affect

In some organisms,a special tRNA recognizes the UAG stop codon but incorporates the amino acid

The coding regions of a eukaryotic gene are known as ________.

Transcription of ribosomal RNA is primarily the function of

Which of the following is associated with the production of multiple mRNAs from a single gene?

The technique used to initially identity promoter sequences was