Question 1

Which of the following processes is central to the initiation of transcription?

Accepted Answer

The binding of sigma to the promoter region is central to the initiation of transcription in bacteria. Sigma is a subunit of RNA polymerase that recognizes specific DNA sequences in the promoter region and helps orient the RNA polymerase enzyme properly for transcription to begin. Without sigma binding, RNA polymerase would not be able to initiate transcription at the correct location.

Question 2

A primary transcript in the nucleus of a eukaryotic cell is the functional mRNA, while a primary transcript in a prokaryotic cell is _ the functional mRNA.

Accepted Answer

In eukaryotic cells, the primary transcript undergoes processing (including splicing, 5' capping, and polyadenylation) to become a smaller, functional mRNA. In prokaryotic cells, the primary transcript is often the functional mRNA and does not require extensive processing, making it the same size as the functional mRNA.

Question 3

In eukaryotic cells, transcription cannot begin until which of the following occurs?

Accepted Answer

Before transcription can begin in eukaryotic cells, several transcription factors must bind to the promoter region of the DNA. These factors help to attract and position RNA polymerase, which is the enzyme responsible for synthesizing the RNA transcript. Without the binding of transcription factors, the RNA polymerase cannot initiate transcription.

Question 4

As scientists were unraveling the mysteries associated with transcription and translation, they discovered there was not a one- to- one correspondence between nucleotide sequence of a gene and base sequence of the mRNA it codes for. They proposed the genes- in- pieces hypothesis. How can the genes- in- pieces hypothesis be explained?

Accepted Answer

The genes-in-pieces hypothesis proposes that genes are composed of both coding and noncoding segments, called exons and introns, respectively. Introns are present in the initial transcript but are removed by splicing, leaving only the coding exons to be translated into protein.

Question 5

Death cap mushrooms produce a substance called - amanitin. a- amanitin efficiently blocks synthesis of mRNA, but not of tRNA or rRNA in eukaryotic organisms. How is that possible?

Accepted Answer

RNA polymerase II is responsible for transcribing mRNA in eukaryotic organisms, while RNA polymerase I transcribes rRNA and RNA polymerase III transcribes tRNA. a-amanitin efficiently interferes with the action of RNA polymerase II, but not RNA polymerase I or III, which explains why it blocks synthesis of mRNA but not of tRNA or rRNA.

Question 6

What molecule is responsible for the catalytic activity in the spliceosomes that are involved in removal of introns?

Accepted Answer

Ribozymes are RNA molecules that can catalyze chemical reactions. The spliceosomes involved in removing introns contain catalytic RNA molecules called ribozymes, which are responsible for the catalytic activity of the spliceosome.

Question 7

David Pribnow studied the base sequences of promoters in bacteria and bacterial viruses. He found two conserved regions in these promoters the - 10 box and the - 35 box). What is the function of these two regions of the promoter?

Accepted Answer

The -10 and -35 boxes are recognized by the sigma subunit of RNA polymerase, allowing for proper positioning of the enzyme at the initiation site for transcription.

Question 8

a- amanitin is a toxin produced by the death cap mushroom. It blocks the synthesis of mRNA. What effect would it have on health of the organism that ate death cap mushrooms?

Accepted Answer

Amanitin blocks the synthesis of mRNA, which is essential for protein synthesis. Without protein synthesis, cellular processes would eventually shut down, leading to organ failure and ultimately death.

Question 9

In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after she has removed the mRNA's 5' cap and poly- A tail. Which of the following would you expect her to find?

Accepted Answer

The 5' cap and poly-A tail protect mRNA from degradation. Without them, the mRNA is quickly degraded by exonucleases.

Question 10

Which molecule or reaction supplies the energy for polymerization of nucleotides in the process of transcription?

Accepted Answer

The phosphate bonds in the nucleotide triphosphates that serve as substrates supply the energy for polymerization of nucleotides during transcription. As each nucleotide triphosphate is added to the growing RNA chain, two of the phosphate groups are cleaved off, releasing energy that drives the formation of the phosphodiester bond between the new nucleotide and the previous nucleotide in the chain. The energy from ATP and the unwinding of the DNA molecule also play roles in transcription, but the primary source of energy for polymerization is the phosphate bonds in the nucleotide triphosphates.

Question 11

Figure 17.1
-The enzyme complex associated with DNA in the figure is

Accepted Answer

The answer of

Figure 17.1
-The enzyme complex associated with DNA...

Question 12

Eukaryotes have three nuclear RNA polymerases. The primary function of RNA polymerase II is

Accepted Answer

RNA polymerase II functions in the transcription of protein-coding genes.

Question 13

How are RNA hairpin turns related to termination?

Accepted Answer

Hairpin turns in RNA are formed by complementary base pairing within the RNA molecule itself. This structure can cause the RNA polymerase to pause or dissociate from the RNA, leading to the termination of transcription.

Question 14

There should be a strong positive correlation between the rate of protein synthesis and

Accepted Answer

The rate of protein synthesis is directly related to the number of ribosomes, as ribosomes are the cellular structures responsible for protein synthesis. The size of the genome, size of mRNA, and quantity of DNA polymerase do not necessarily correlate with the rate of protein synthesis.

Question 15

$\text {Genes and RNA transcripts differ in length.}$
  Figure 17.2
-Refer to Figure 17.2. The mRNA is smaller than the length of the DNA that codes for it because

Accepted Answer

Post-transcriptional modification removes the introns, leaving only the exons that code for the mRNA. This reduces the length of the mRNA compared to the DNA that codes for it.

Question 16

RNA polymerase needs a subunit to initiate transcription that is not needed for transcript elongation. What is the subunit?

Accepted Answer

Sigma is a subunit of RNA polymerase that is responsible for recognizing specific DNA sequences and promoting the formation of the transcription initiation complex. Once transcription is initiated, sigma is no longer needed and can detach from the RNA polymerase complex. Therefore, sigma is only required for transcription initiation and not for elongation.

Question 17

Transcription would not occur at the appropriate initiation sites in E. coli if RNA polymerase is missing which of the following?

Accepted Answer

Sigma is responsible for recognizing and binding to the promoter region of DNA, thereby allowing RNA polymerase to initiate transcription at the appropriate site. Without sigma, RNA polymerase may bind to random sites on DNA and/or not recognize the proper promoter regions, leading to incorrect transcription initiation sites. Therefore, choice D is the correct answer.

Question 18

The segments of DNA where transcription begins have a binding site for RNA polymerase. These segments are known as

Accepted Answer

Promoters are DNA sequences that define the beginning of a gene and serve as a binding site for RNA polymerase. Initiation factors and sigma are involved in the initiation of transcription, but they do not refer specifically to the DNA sequence where transcription begins. The holoenzyme refers to the complete RNA polymerase complex, including sigma and other subunits.

Question 19

Put the following events of transcription in chronological order.
1) Sigma binds to the promoter region.
2) The double helix of DNA is unwound, breaking hydrogen bonds between complementary strands.
3) Sigma binds to RNA polymerase.
4) Sigma is released.
5) Transcription begins.

Accepted Answer

The correct sequence for the events of transcription is: Sigma binds to RNA polymerase, Sigma binds to the promoter region, the double helix of DNA is unwound, transcription begins, and finally, Sigma is released.

Question 20

During elongation, RNA polymerase has three prominent channels, or grooves. These channels provide sites for all of the following, EXCEPT

Accepted Answer

During elongation by RNA polymerase, there are indeed three prominent channels: one for the entry of ribonucleoside triphosphates (NTPs), one for the growing RNA strand, and one for the double-stranded DNA template. However, there is no specific channel dedicated for the exit of diphosphates (the by-products of NTP incorporation into the RNA strand); these molecules typically diffuse away from the enzyme.

Quiz 17: Transcription, Rna Processing, and Translation

Which of the following processes is central to the initiation of transcription?

A primary transcript in the nucleus of a eukaryotic cell is the functional mRNA, while a primary transcript in a prokaryotic cell is _ the functional mRNA.

In eukaryotic cells, transcription cannot begin until which of the following occurs?

Death cap mushrooms produce a substance called - amanitin. a- amanitin efficiently blocks synthesis of mRNA, but not of tRNA or rRNA in eukaryotic organisms. How is that possible?

What molecule is responsible for the catalytic activity in the spliceosomes that are involved in removal of introns?

David Pribnow studied the base sequences of promoters in bacteria and bacterial viruses. He found two conserved regions in these promoters the - 10 box and the - 35 box) . What is the function of these two regions of the promoter?

a- amanitin is a toxin produced by the death cap mushroom. It blocks the synthesis of mRNA. What effect would it have on health of the organism that ate death cap mushrooms?

In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after she has removed the mRNA's 5' cap and poly- A tail. Which of the following would you expect her to find?

Which molecule or reaction supplies the energy for polymerization of nucleotides in the process of transcription?

Figure 17.1 -The enzyme complex associated with DNA in the figure is

Eukaryotes have three nuclear RNA polymerases. The primary function of RNA polymerase II is

How are RNA hairpin turns related to termination?

There should be a strong positive correlation between the rate of protein synthesis and

RNA polymerase needs a subunit to initiate transcription that is not needed for transcript elongation. What is the subunit?

Transcription would not occur at the appropriate initiation sites in E. coli if RNA polymerase is missing which of the following?

The segments of DNA where transcription begins have a binding site for RNA polymerase. These segments are known as

Put the following events of transcription in chronological order. 1) Sigma binds to the promoter region. 2) The double helix of DNA is unwound, breaking hydrogen bonds between complementary strands. 3) Sigma binds to RNA polymerase. 4) Sigma is released. 5) Transcription begins.

During elongation, RNA polymerase has three prominent channels, or grooves. These channels provide sites for all of the following, EXCEPT

Quiz 17: Transcription, Rna Processing, and Translation

Which of the following processes is central to the initiation of transcription?

A primary transcript in the nucleus of a eukaryotic cell is the functional mRNA, while a primary transcript in a prokaryotic cell is _ the functional mRNA.

In eukaryotic cells, transcription cannot begin until which of the following occurs?

Death cap mushrooms produce a substance called - amanitin. a- amanitin efficiently blocks synthesis of mRNA, but not of tRNA or rRNA in eukaryotic organisms. How is that possible?

What molecule is responsible for the catalytic activity in the spliceosomes that are involved in removal of introns?

David Pribnow studied the base sequences of promoters in bacteria and bacterial viruses. He found two conserved regions in these promoters the - 10 box and the - 35 box) . What is the function of these two regions of the promoter?

a- amanitin is a toxin produced by the death cap mushroom. It blocks the synthesis of mRNA. What effect would it have on health of the organism that ate death cap mushrooms?

In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after she has removed the mRNA's 5' cap and poly- A tail. Which of the following would you expect her to find?

Which molecule or reaction supplies the energy for polymerization of nucleotides in the process of transcription?

Figure 17.1 -The enzyme complex associated with DNA in the figure is

Eukaryotes have three nuclear RNA polymerases. The primary function of RNA polymerase II is

How are RNA hairpin turns related to termination?

There should be a strong positive correlation between the rate of protein synthesis and

Genes and RNA transcripts differ in length.\text {Genes and RNA transcripts differ in length.}Genes and RNA transcripts differ in length. Figure 17.2 -Refer to Figure 17.2. The mRNA is smaller than the length of the DNA that codes for it because

RNA polymerase needs a subunit to initiate transcription that is not needed for transcript elongation. What is the subunit?

Transcription would not occur at the appropriate initiation sites in E. coli if RNA polymerase is missing which of the following?

The segments of DNA where transcription begins have a binding site for RNA polymerase. These segments are known as

Put the following events of transcription in chronological order. 1) Sigma binds to the promoter region. 2) The double helix of DNA is unwound, breaking hydrogen bonds between complementary strands. 3) Sigma binds to RNA polymerase. 4) Sigma is released. 5) Transcription begins.

During elongation, RNA polymerase has three prominent channels, or grooves. These channels provide sites for all of the following, EXCEPT