Transcription Quiz
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Questions and Answers

Which region of a gene contains the consensus sequence?

  • Terminator region
  • Template strand
  • Coding region
  • Promotor region (correct)

Which region of a gene specifies the end of transcription?

  • Terminator region (correct)
  • Promotor region
  • Template strand
  • Coding region

Which strand of DNA is transcribed into RNA?

  • Non-template strand
  • Template strand (correct)
  • Sense strand

What is the main key enzyme for transcription?

<p>RNA polymerase (A)</p> Signup and view all the answers

In which direction does RNA polymerase work?

<p>5' to 3' (C)</p> Signup and view all the answers

What is the first stage of transcription?

<p>Initiation (B)</p> Signup and view all the answers

What is the consensus sequence recognized by transcription initiation factors in eukaryotes called?

<p>TATA box (B)</p> Signup and view all the answers

What is the role of general transcription factor TFII?

<p>Recognize and bind the TATA box (A)</p> Signup and view all the answers

Where is the TATA box located in relation to the transcription start site?

<p>~25 nucleotides upstream (C)</p> Signup and view all the answers

What is the role of silencers in transcription initiation?

<p>They inhibit gene transcription (A)</p> Signup and view all the answers

What happens during the elongation phase of transcription?

<p>RNA Polymerase II moves downstream along the DNA (C)</p> Signup and view all the answers

What is the role of chromatin remodeling complexes during elongation?

<p>They help RNA Polymerase II navigate the chromatin structure (D)</p> Signup and view all the answers

What is the role of histone chaperones during elongation?

<p>They disassemble/reassemble nucleosomes (B)</p> Signup and view all the answers

What is the role of DNA topoisomerase during elongation?

<p>They remove supercoils (A)</p> Signup and view all the answers

What are the three main ways in which pre-mRNA is processed in eukaryotes?

<p>Splicing, capping the 5' end, polyadenylation of the 3' end (D)</p> Signup and view all the answers

What is the function of the 5' cap on mRNA?

<p>It facilitates export of the mRNA into the cytosol (C)</p> Signup and view all the answers

What is the function of the poly-A tail on mRNA?

<p>It protects the mRNA from degradation (B)</p> Signup and view all the answers

Prokaryotic mRNA has a cap and a tail like eukaryotic mRNA but it doesn't get spliced

<p>False (B)</p> Signup and view all the answers

Prokaryotic mRNA is considered polycistronic because..

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Prokaryotic mRNA does NOT get exported from the nucleus

<p>True (A)</p> Signup and view all the answers

Steps of prokaryotic and eukaryotic transcription are the same except for the processing of mRNA

<p>True (A)</p> Signup and view all the answers

Match the following elements of the transcription process to their respective functions:

<p>TATA box = Binding site for the transcription factor TFIID Silencers = Binding site for repressor proteins that inhibit gene transcription Enhancers = Binding site for transcriptional activator proteins that increase the rate of transcription DNA topoisomerase = Enzyme that relieves super-helical tension during transcription elongation</p> Signup and view all the answers

Match the following elements of pre-mRNA processing in eukaryotes to their respective functions:

<p>Splicing = Removal of intron sequences from the transcribed RNA 5’ cap = Facilitates export of the mRNA into the nucleus and is involved in translation Polyadenylation of 3’ end = Protects the mRNA from degradation and facilitates export from the nucleus Histone chaperones = Assist in partially disassembling &amp; reassembling nucleosomes as an RNA Polymerase passes through</p> Signup and view all the answers

Match the following elements of prokaryotic and eukaryotic transcription to their respective characteristics:

<p>Eukaryotic transcription = Involves 5’ cap, splicing, and poly-A tail Prokaryotic transcription = Does not require 5’ cap, splicing, or poly-A tail Eukaryotic mRNA = Requires export from the nucleus Prokaryotic mRNA = Does not require export from the nucleus and can begin translation right away</p> Signup and view all the answers

Flashcards

Consensus sequence

The specific sequence of DNA found in the promoter region of a gene that helps RNA polymerase identify the start of transcription.

Termination sequence

A sequence of DNA that signals the end of transcription, telling RNA polymerase to stop copying the DNA.

Template strand

The strand of DNA that serves as the template for RNA synthesis during transcription.

RNA polymerase

The enzyme responsible for building RNA molecules during transcription by using DNA as a template.

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Direction of RNA synthesis

RNA polymerase adds nucleotides to the growing RNA strand in this direction, from the 5' end to the 3' end.

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Transcription initiation

The first stage of transcription where RNA polymerase binds to the promoter region of a gene and initiates RNA synthesis.

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TATA box

A sequence of DNA located about 25-30 base pairs upstream of the transcription start site. It helps guide RNA polymerase to the correct starting point for transcription in eukaryotes.

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TFII (Transcription Factor II)

A type of transcription factor that plays a crucial role in recruiting RNA polymerase to the promoter region and initiating transcription.

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TATA box location

Located about 25-30 base pairs upstream of the transcription start site, it helps guide RNA polymerase to the right spot to begin transcription.

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Silencers

DNA elements that repress transcription initiation by binding to repressor proteins. They essentially silence the gene by blocking RNA polymerase.

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Elongation

The second stage of transcription where RNA polymerase moves along the DNA template strand, adding nucleotides to the growing RNA molecule.

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Chromatin remodeling complexes

These complexes change the structure of chromatin, making the DNA more accessible for RNA polymerase to transcribe.

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Histone chaperones

These proteins assist in reorganizing nucleosomes during transcription, helping RNA polymerase move smoothly along the DNA.

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DNA topoisomerase

This enzyme relieves the stress caused by the unwinding of DNA during transcription, preventing supercoiling that can interfere with the process.

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Pre-mRNA

Newly synthesized RNA that is not yet fully processed in eukaryotes.

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5' cap

A chemical modification that protects pre-mRNA from degradation and helps ribosomes bind to it during translation in eukaryotes.

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Poly-A tail

A series of adenine nucleotides added to the 3' end of mRNA in eukaryotes, enhancing its stability and aiding in its export from the nucleus.

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Polycistronic mRNA

A type of mRNA found in prokaryotes that can encode multiple proteins from a single RNA molecule.

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Prokaryotic mRNA processing

A distinct difference between prokaryotic and eukaryotic mRNA is that prokaryotic mRNA doesn't undergo splicing and doesn't have a 5' cap or a poly-A tail.

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Coupled transcription and translation

The simultaneous occurrence of transcription and translation in prokaryotes, due to the absence of a nuclear membrane.

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Prokaryotic vs. Eukaryotic transcription

The process of creating an RNA copy of DNA is similar in both prokaryotes and eukaryotes, but the post-transcriptional processing of mRNA is different.

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mRNA location

Eukaryotic mRNA, which is processed in the nucleus, is exported to the cytoplasm for translation, while prokaryotic mRNA remains in the cytoplasm.

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Splicing difference

Eukaryotic mRNA undergoes splicing to remove introns and keep exons, while prokaryotic mRNA does not undergo splicing.

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Study Notes

Gene Structure and Transcription

  • Consensus sequence is found in the promoter region of a gene.
  • The termination sequence specifies the end of transcription.
  • The template strand of DNA is transcribed into RNA.
  • RNA polymerase is the main enzyme for transcription.
  • RNA polymerase synthesizes RNA in the 5' to 3' direction.

Stages of Transcription

  • First stage of transcription is initiation.
  • The consensus sequence recognized by transcription initiation factors in eukaryotes is called the TATA box.
  • General transcription factor TFII plays a role in recruiting RNA polymerase to the promoter.

TATA Box and Transcription Initiation

  • The TATA box is located about 25-30 base pairs upstream of the transcription start site.
  • Silencers are DNA elements that repress transcription initiation by binding repressor proteins.

Elongation Phase of Transcription

  • During elongation, RNA polymerase adds nucleotides to the growing RNA strand.
  • Chromatin remodeling complexes facilitate access to DNA by altering chromatin structure during elongation.
  • Histone chaperones assist in reorganizing nucleosomes as transcription progresses.
  • DNA topoisomerase alleviates supercoiling ahead of RNA polymerase during elongation.

Pre-mRNA Processing in Eukaryotes

  • Pre-mRNA is processed through splicing, capping, and polyadenylation.
  • The 5' cap on mRNA protects the mRNA from degradation and assists in ribosome binding.
  • The poly-A tail on mRNA enhances stability and aids in the export of mRNA from the nucleus.

Prokaryotic vs. Eukaryotic mRNA

  • Prokaryotic mRNA is polycistronic, meaning it can encode multiple proteins from a single RNA molecule.
  • Unlike eukaryotic mRNA, prokaryotic mRNA does not get processed into introns/exons and lacks a cap and a tail.
  • Transcription and translation occur simultaneously in prokaryotes since there is no nuclear membrane.

Comparison of Transcription Processes

  • Steps of transcription are similar in prokaryotes and eukaryotes, aside from the processing of mRNA.
  • Prokaryotic mRNA does not undergo splicing and remains in the cytoplasm, while eukaryotic mRNA is exported after processing.

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Description

Test your knowledge on transcriptional units and gene structure! This quiz will cover the three general regions found in all genes - the promoter region, coding region, and terminator region. Challenge yourself to identify key elements such as the transcription start site and template strand. Get ready to dive into the world of gene transcription!

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