Prokaryotic Transcription Overview Part II-A Transcription (Exam 2)
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Questions and Answers

What differentiates amateur practice from professional practice?

  • Amateurs stop when they succeed, while professionals practice until they cannot fail. (correct)
  • Amateurs seek immediate results, while professionals aim for long-term mastery.
  • Amateurs practice frequently, while professionals practice occasionally.
  • Amateurs focus on perfection, while professionals focus on consistency.

Which part is NOT typically found in a prokaryotic gene?

  • RNA coding region
  • Transcription terminator
  • Exon-intron structure (correct)
  • Promoter

What is a function of the promoter in a prokaryotic gene?

  • To specify the amino acid sequence of proteins.
  • To signal the termination of transcription.
  • To initiate the binding of transcription factors. (correct)
  • To provide a template for mRNA synthesis.

Which consensus sequence is part of E. coli promoters?

<p>-35 element (D)</p> Signup and view all the answers

What is the function of the transcription terminator in a prokaryotic gene?

<p>To signal where transcription should end. (C)</p> Signup and view all the answers

Which of the following elements is NOT included in bacterial promoters?

<p>Poly-A tail (D)</p> Signup and view all the answers

What is the first step of transcription initiation in E. coli?

<p>Formation of the closed complex (A)</p> Signup and view all the answers

Which element serves as a core-recognition element in bacterial promoters?

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

What are the components found in the structure of a prokaryotic gene?

<p>Promoter, RNA Coding Region, Terminator (A)</p> Signup and view all the answers

Which region is responsible for initiating transcription in prokaryotic DNA?

<p>Promoter (D)</p> Signup and view all the answers

What is the function of sigma domain 2 during transcription?

<p>To interact with the promoter -10 element (A)</p> Signup and view all the answers

In the structure of prokaryotic mRNA, what do the terms ORF 1 and ORF 2 refer to?

<p>Open Reading Frames that code for proteins (C)</p> Signup and view all the answers

What occurs at position +1 during transcription in prokaryotes?

<p>The DNA is unwound for RNA polymerase access (C)</p> Signup and view all the answers

Which component interacts with the -35 element of the prokaryotic promoter?

<p>Sigma domain 4 (A)</p> Signup and view all the answers

In prokaryotic mRNA, what does the 5' UTR primarily function as?

<p>To facilitate ribosome binding during translation (A)</p> Signup and view all the answers

What structural feature is NOT present in prokaryotic genes?

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

What is the role of the sigma factor in transcription?

<p>It prevents the access of the template to the RNAP active site. (B)</p> Signup and view all the answers

Which sigma domain is responsible for interacting with the -35 element?

<p>Sigma domain 4 (D)</p> Signup and view all the answers

What triggers the dissociation of the sigma factor during transcription?

<p>The completion of approximately 12 nucleotides of RNA synthesis (A)</p> Signup and view all the answers

What is the structure of the intrinsic terminator sequence in transcription termination?

<p>A GC-rich palindrome followed by a poly-A stretch (A)</p> Signup and view all the answers

What occurs during abortive initiation in transcription?

<p>Short RNA transcripts between 2-6 nucleotides are produced. (B)</p> Signup and view all the answers

How does Rho factor contribute to factor-dependent termination?

<p>It interacts with the transcript at the rut site while moving 5' to 3'. (B)</p> Signup and view all the answers

What is the function of sigma domain 2 during transcription initiation?

<p>It interacts with the non-template strand at -10 to facilitate melting. (B)</p> Signup and view all the answers

Which feature is NOT characteristic of intrinsic termination of transcription?

<p>Dissociation of Rho factor from RNA (C)</p> Signup and view all the answers

Flashcards

Protein-coding gene

A nucleotide sequence that specifies the order of amino acids in a polypeptide.

RNA gene

A nucleotide sequence that specifies the order of RNA nucleotides.

Promoter (gene)

A DNA region that signals where transcription begins and sets the direction.

Transcription Terminator

A DNA sequence signaling the end of RNA synthesis.

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Pribnow box

A consensus sequence in E. coli promoters, crucial for transcription initiation.

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Transcription initiation (E.coli)

The first stage of transcription in E. coli, where the RNA polymerase binds to the promoter.

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Transcription elongation

The stage of transcription where RNA polymerase moves along the DNA template, synthesizing the RNA molecule.

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Consensus sequence

A short, specific DNA sequence that is highly conserved across different genes or organisms.

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Intrinsic termination

Transcription termination that occurs without the help of proteins, based on a specific DNA sequence.

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Factor-dependent termination

Transcription termination that requires a protein called Rho to remove RNA polymerase from the DNA.

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Sigma factor

A protein that helps RNA polymerase recognize and bind to the promoter region of DNA.

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Sigma Factor Domains (order)

Different sigma factor domains bind to specific DNA sequences, helping RNA polymerase initiate transcription.

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Abortive initiation

The initial, short bursts of RNA synthesis that occur before transcription elongation.

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RNA Polymerase

The enzyme responsible for synthesizing RNA from a DNA template.

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Prokaryotic gene structure

A segment of DNA containing a promoter, regulatory sequences, and a coding region for RNA.

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Promoter region

DNA sequence that signals the start of transcription.

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RNA Coding Region

Part of the gene that specifies the amino acid sequence of the protein.

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Prokaryotic mRNA structure

Single-stranded RNA molecule that carries the genetic code for protein synthesis.

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5' and 3' UTRs

Untranslated regions of mRNA located at the 5' and 3' ends, crucial for stability and translation.

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ORF (Open Reading Frame)

Sequence of mRNA coding for protein synthesis.

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Transcription (bacteria)

Process of creating an mRNA molecule from a DNA template.

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Sigma factors (-10 and -35 elements)

Protein components of bacterial RNA polymerase that enable recognition of DNA promoter sequences.

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Study Notes

Prokaryotic Transcription

  • Amateur practices until right, professional until cannot get wrong.
  • Prokaryotic genes have a promoter, an RNA-coding region, and a transcription terminator.
  • Gene structure involves a protein-coding gene with a nucleotide sequence encoding amino acid order in a polypeptide. There is also an RNA gene, whose sequence determines the rNTP order in an RNA molecule.
  • In E. coli promoters, consensus sequences are -35 and -10 elements.
  • Additional regulatory elements exist in bacterial promoters, such as UP element, EXT, DIS, and CRE. Bacterial promoters don't always contain all of these elements.
  • Transcription initiation involves promoter recognition, formation of closed and open complex.
  • Transcription elongation is an ongoing process.
  • Transcription termination has two types: intrinsic and factor-dependent.

Transcription in E. coli

  • Transcription initiation detailed steps: promoter recognition, formation of the closed complex, and formation of the open complex.
  • The sigma factor recognizes and binds to promoter consensus sequences.
  • Sigma factor domains interact with different parts of the promoter: sigma 4 to -35 element, sigma 3 to EXT, sigma 2 to -10 element, and sigma 1 to RNAP active site.
  • Sigma domain 1 blocks template access to RNA polymerase.
  • Sigma domain 2 interacts with -10 sequences causing strand melting.
  • Sigma domain 3 interacts with EXT, and 4 with -35.
  • Abortive initiation involves 2-6 nucleotides.
  • After ~12 nucleotides, sigma factor dissociates.

Prokaryotic mRNA

  • Prokaryotic mRNA structure includes the Shine-Dalgarno sequence for bacteria (not other prokaryotes), a 5' untranslated region, a protein coding region, and a 3' untranslated region.
  • Start and stop codons are a part of prokaryotic mRNA.

RNA Polymerase

  • RNA polymerase holoenzyme binds to the promoter.
  • The RNA polymerase transcription bubble forms.

Transcription Termination

  • Intrinsic termination involves a GC-rich palindrome followed by a poly-A stretch on the template strand. This creates a GC hairpin loop leading to weak U:A hybrid separation.
  • Factor-dependent termination involves the rho factor interacting with the rut site on the transcript and moving toward the 3' end. It separates RNA polymerase from the template.

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Transcription In Prokaryotes PDF

Description

Explore the fundamental processes of prokaryotic transcription, focusing on E. coli. This quiz covers gene structures, promoter elements, and the stages of transcription initiation, elongation, and termination. Test your knowledge on the intricate details of how transcription occurs in bacterial cells.

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