Which of the following is not true about prokaryotic transcription?

Study Groups

Study with other students and unlock Numerade solutions for free.

In order to continue enjoying our site, we ask that you confirm your identity as a human. Thank you very much for your cooperation.

← Previous 1 2 3 4 Next →

Which of these does not contribute to the termination of RNA transcription in bacteria?

Possible Answers:

Disruption of uracil-adenine RNA-DNA hybrid

Reattachment of the sigma factor

Correct answer:

Reattachment of the sigma factor

Explanation:

The sigma factor is an important part of initiation for prokaryotic transcription. Once transcription has been initiated, however, the sigma factor is released during elongation. RNA polymerase synthesizes the RNA product until it is interrupted in one of two ways. In rho-dependent termination, a rho factor protein interferes with RNA polymerase binding and causes it to release the DNA strand. In rho-independent termination, structural features of the DNA cause RNA polymerase to become detached. The structures include hairpin loops, which generate steric hindrance, and adenine-rich sequences, which lead to weak binding of the RNA product to the DNA template.

In prokaryotic transcription, which of the following is recruited to facilitate the binding of the synthesis enzyme to the DNA template?

Possible Answers:

Correct answer:

The sigma factor

Explanation:

Inactive RNA polymerase must bind to a specific sigma factor in order to become active in gene transcription. Sigma factors are specialized transcription factors involved in recruiting and activating RNA polymerase. Only once RNA polymerase has bound the sigma factor can it identify promoter sequences and initiate transcription.

mRNA is the product of transcription and is not involved in prokaryotic RNA polymerase recruitment. An RNA primer is essential to recruiting DNA polymerase for DNA replication.

Which of the following is not true about prokaryotic transcription?

Possible Answers:

RNA polymerase binds directly to the Shine-Delgarno sequence for some promoters

mRNA is not subject to post-transcriptional modifications

RNA polymerase interacts directly with the DNA

Transcription occurs in the cytoplasm

Correct answer:

RNA polymerase binds directly to the Shine-Delgarno sequence for some promoters

Explanation:

RNA polymerase does not interact with the Shine-Delgarno sequence. The Shine-Delgarno sequence is present on some prokaryotic mRNAs and serves as a ribosomal binding site for the initiation of translation. RNA polymerase is only involved in transcription and will bind to DNA, not RNA.

The other answers are all true and unique to prokaryotic transcription. Eukaryotic transcription is much more tightly regulated by transcription factors and DNA packaging (chromatin), and is confined to the nucleus.  

Which of these are characteristic of transcription in eukaryotes? 

I.  Transcription can occur at the same time as translation

II.  The resulting RNA molecule is functionally mature

III.  The resulting RNA molecule must undergo splicing and other modifications before it is functional

IV.  Transcription occurs in the cytoplasm

Possible Answers:

Explanation:

Prokaryotic transcription occurs in the cytosol, since prokaryotes lack a nucleus. This allows ribosomes to interact with RNA even while it is still be synthesized.

In contrast, eukaryotic transcription occurs in the nucleus. Once RNA has been synthesized it must be transported from the nucleus to the cytoplasm before it can interact with ribosomes. The newly-synthesized RNA undergoes splicing to remove introns, addition of a 5'-cap, and addition of a poly-A tail before it can exit the nucleus. These modifications help prevent degradation of the RNA. Only after these modifications can the RNA leave the nucleus and becomes functionally active.

What is a Shine-Delgarno sequence?

Possible Answers:

A site for restriction endonuclease digestion

A polymerase binding site in eukaryotic RNA primers

A ribosomal binding site in prokaryotic mRNA

A ribosomal binding site in eukaryotic mRNA

A polymerase binding site in prokaryotic DNA

Correct answer:

A ribosomal binding site in prokaryotic mRNA

Explanation:

Shine-Delgarno sequences are ribosomal binding sites slightly upstream of start codons on prokaryotic mRNA. Eukaryotic mRNA is more complicated (it does not contain Shine-Delgarno sequences) and contains promoter regions that are responsible for recruiting translation factors and ribosomal subunits. 

How does prokaryotic transcription differ from eukaryotic transcription?

Possible Answers:

Prokaryotic transcripts are polycistronic

Prokaryotic transcripts are translated directly in the nucleus

Prokaryotic RNA polymerase transcribes the coding strand, rather than the template strand

Only prokaryotes use promoters

Correct answer:

Prokaryotic transcripts are polycistronic

Explanation:

While prokaryotic and eukaryotic transcription processes are quite similar, there are some key differences. One significant difference is that prokaryotic transcripts can contain multiple genes, which will then transition as a single RNA strand to the ribosome. This is referred to as a polycistronic transcript. Eukaryotes have only one gene per transcript.

Both prokaryotes and eukaryotes use promoters. Prokaryotes do not have nuclei, though transcription and translation can occur simultaneously and in close proximity in these cells.

In a bacterial cell, RNA polymerase binds to a promoter. What needs to bind to RNA polymerase for transcription to initiate?

Possible Answers:

Correct answer:

A sigma factor

Explanation:

In bacterial cells, binding of a sigma factor to RNA polymerase is required for the initiation of transcription. Once the sigma factor binds, RNA polymerase is referred to as a holoenzyme and begins to make the RNA transcript.

Which of the following correctly pairs the part of an operator with its function?

Possible Answers:

Corepressor; signals for RNA polymerase to binds and transcribe genes

Promoter; contains the genes to be transcribed

Operator; region where the repressor binds

Inducer; decreases RNA polymerases’ transcription of genes

Correct answer:

Operator; region where the repressor binds

Explanation:

The operator region is the location where the repressor binds. Other parts of an operon include the promoter (where RNA polymerase binds), and structural genes.

How is transcription controlled in prokaryotes?

Possible Answers:

Addition of 3’ polyadenylated tail

Correct answer:

Repressor and activators

Explanation:

Addition of 5’ cap, 3’ tail, and intron splicing occur in eukaryotes, not prokaryotes. Repressors bind to the operator region of the gene and prevent RNA polymerase from transcribing the gene, while activators bind to the promoter and increase transcription of the gene.

Which of the following binds to the repressor of an operon to prevent the repressor from binding to the operator region?

Possible Answers:

Explanation:

A repressor is a molecule that binds to the operator region of a gene and prevents RNA polymerase from transcribing the genes. An inducer can bind to a repressor, preventing the repressor from binding to the operator region, and thus allowing RNA polymerase to transcribe the genes.

← Previous 1 2 3 4 Next →

If you've found an issue with this question, please let us know. With the help of the community we can continue to improve our educational resources.

If you believe that content available by means of the Website (as defined in our Terms of Service) infringes one or more of your copyrights, please notify us by providing a written notice (“Infringement Notice”) containing the information described below to the designated agent listed below. If Varsity Tutors takes action in response to an Infringement Notice, it will make a good faith attempt to contact the party that made such content available by means of the most recent email address, if any, provided by such party to Varsity Tutors.

Your Infringement Notice may be forwarded to the party that made the content available or to third parties such as ChillingEffects.org.

Please be advised that you will be liable for damages (including costs and attorneys’ fees) if you materially misrepresent that a product or activity is infringing your copyrights. Thus, if you are not sure content located on or linked-to by the Website infringes your copyright, you should consider first contacting an attorney.

Please follow these steps to file a notice:

You must include the following:

A physical or electronic signature of the copyright owner or a person authorized to act on their behalf; An identification of the copyright claimed to have been infringed; A description of the nature and exact location of the content that you claim to infringe your copyright, in \ sufficient detail to permit Varsity Tutors to find and positively identify that content; for example we require a link to the specific question (not just the name of the question) that contains the content and a description of which specific portion of the question – an image, a link, the text, etc – your complaint refers to; Your name, address, telephone number and email address; and A statement by you: (a) that you believe in good faith that the use of the content that you claim to infringe your copyright is not authorized by law, or by the copyright owner or such owner’s agent; (b) that all of the information contained in your Infringement Notice is accurate, and (c) under penalty of perjury, that you are either the copyright owner or a person authorized to act on their behalf.

Send your complaint to our designated agent at:

Charles Cohn Varsity Tutors LLC 101 S. Hanley Rd, Suite 300 St. Louis, MO 63105

Or fill out the form below: