Untitled Quiz
32 Questions
16 Views

Untitled Quiz

Created by
@AppealingChiasmus2500

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of the polyadenylation signal in mRNA?

  • It enhances stability and facilitates export from the nucleus. (correct)
  • It regulates when and where transcription occurs.
  • It ensures proper intron removal during splicing.
  • It codes for amino acids after splicing.

    • Which component of a gene is primarily responsible for coding for amino acids?

  • Promoter
  • Introns
  • Exons (correct)
  • 3' UTR

    • How do the 5' UTR and 3' UTR regions influence gene expression?

  • They both code for proteins.
  • They enhance transcription initiation.
  • They are non-coding and have no effect on gene expression.
  • They influence translation efficiency and mRNA stability. (correct)

    • Which sequence is part of the conserved elements in a prokaryotic promoter region?

    <p>-10 Box</p> Signup and view all the answers

    What role do introns play within a gene structure?

    <p>They may assist in gene regulation and alternative splicing.</p> Signup and view all the answers

    What is the significance of the Shine-Dalgarno sequence in prokaryotic genes?

    <p>It aligns the ribosome for translation initiation.</p> Signup and view all the answers

    What is the main difference between prokaryotic and eukaryotic gene structures?

    <p>Eukaryotic genes contain introns and exons, while prokaryotic genes usually do not.</p> Signup and view all the answers

    What function does the promoter serve in gene expression?

    <p>It regulates when and where transcription occurs.</p> Signup and view all the answers

    What is the start codon in the coding sequence of a gene?

    <p>AUG</p> Signup and view all the answers

    What is the main function of the promoter in gene structure?

    <p>To initiate transcription by providing binding sites for RNA polymerase</p> Signup and view all the answers

    Which feature characterizes a rho-independent terminator region in transcription?

    <p>Contains a hairpin loop followed by uracils</p> Signup and view all the answers

    Which of the following best describes an open reading frame (ORF)?

    <p>A continuous stretch of nucleotides starting with a start codon and ending with a stop codon</p> Signup and view all the answers

    Which of the following describes an operon?

    <p>Multiple genes transcribed from a single promoter</p> Signup and view all the answers

    What is the typical signature sequence of a eukaryotic promoter region?

    <p>5' - TATAAAA - 3'</p> Signup and view all the answers

    What do eukaryotic genes contain that prokaryotic genes typically do not?

    <p>Introns</p> Signup and view all the answers

    How does the coding sequence (CDS) function in a gene?

    <p>It gets translated into protein</p> Signup and view all the answers

    What role do exons play in the processing of mRNA?

    <p>They are coding sequences that remain in mature mRNA</p> Signup and view all the answers

    Which statement accurately describes introns?

    <p>They are non-coding sequences spliced out from pre-mRNA</p> Signup and view all the answers

    What sequence elements are inherent in the core promoter of eukaryotic genes?

    <p>5'-TATAA-3' TATA box</p> Signup and view all the answers

    Which type of terminators signal the end of transcription in prokaryotic genes?

    <p>Both Rho-dependent and Rho-independent terminators</p> Signup and view all the answers

    What marks the 5' splice site of an intron?

    <p>5' - GU - 3'</p> Signup and view all the answers

    What is the function of the Rho protein in transcription termination?

    <p>It helps terminate transcription at rho-dependent sites</p> Signup and view all the answers

    What aspect distinguishes the 5' untranslated region (UTR) in eukaryotic genes?

    <p>It influences the efficiency of translation</p> Signup and view all the answers

    What distinguishes the codon in the coding region of a gene?

    <p>Codons dictate the amino acid sequence of the resulting protein</p> Signup and view all the answers

    What role does the 5' UTR play in gene regulation?

    <p>It contains sequences that affect translation efficiency.</p> Signup and view all the answers

    Which of the following describes enhancers in gene expression?

    <p>They can increase transcription from a distance.</p> Signup and view all the answers

    What is the DNA signature for the polyadenylation signal in eukaryotic genes?

    <p>AAUAAA</p> Signup and view all the answers

    What is the primary function of the 3' UTR in mRNA?

    <p>To influence mRNA stability and localization.</p> Signup and view all the answers

    Which sequence is characteristic of eukaryotic promoters?

    <p>TATAAAA</p> Signup and view all the answers

    Which of the following is NOT typically found in prokaryotic gene structure?

    <p>Intron sequences</p> Signup and view all the answers

    What is the effect of silencer elements on gene expression?

    <p>They suppress gene expression.</p> Signup and view all the answers

    Which statement about the ribosome binding site in prokaryotes is correct?

    <p>It includes the Shine-Dalgarno sequence.</p> Signup and view all the answers

    Study Notes

    Gene Structure and Function

    • A gene is a segment of DNA that provides instructions for creating proteins or functional RNA molecules.
    • Genes are fundamental units of heredity, meaning they are passed down from parents to offspring.
    • Genes can undergo mutations (changes in DNA sequence) and recombination (exchange of genetic material).

    Coding Sequence (CDS)

    • The CDS is the portion of a gene that is translated into a protein.
    • It starts with a start codon (AUG) and ends with a stop codon (UAA, UAG, or UGA).
    • The CDS contains specific nucleotide sequences that determine the order of amino acids in the protein.

    Open Reading Frame (ORF)

    • An ORF is a continuous stretch of nucleotides within DNA that potentially codes for a protein.
    • An ORF starts with a start codon and ends with a stop codon.
    • Not all ORFs correspond to functional proteins.

    Prokaryotic Gene Structure

    • Prokaryotic genes are relatively simple and organized into operons.
    • Promoter: This region located upstream of the coding region controls the initiation of transcription.
      • It contains conserved sequences:
        • -10 region (Pribnow box): 5'-TATAAT-3'
        • -35 region: 5'-TTGACA-3'
    • Coding Region: This region codes for the protein and does not contain introns.
      • It starts with a start codon (AUG) and ends with a stop codon (UAA, UAG, or UGA).
    • Terminator: This sequence signals the end of transcription, ensuring proper regulation.
      • It can be Rho-dependent or Rho-independent.

    Eukaryotic Gene Structure

    • Eukaryotic genes are more complex than prokaryotic genes, containing several distinct elements.
    • Promoter:
      • Core Promoter: Recognized by RNA polymerase, often containing the TATA box (5'-TATAA-3').
      • Proximal Promoter: Contains binding sites for regulatory elements.
      • Distal Promoter: Further upstream with additional regulatory elements.
    • Exons and Introns:
      • Exons: Coding sequences that remain in the mature mRNA after splicing.
      • Introns: Non-coding sequences that are spliced out of pre-mRNA.
      • Signature sequences:
        • Splice donor sites: 5'-GU-3' at the beginning of introns.
        • Splice acceptor sites: 5'-AG-3' at the end of introns.
    • 5' Untranslated Region (UTR):
      • The region upstream of the coding sequence that can influence translation efficiency.
    • 3' Untranslated Region (UTR):
      • The region downstream of the coding sequence that plays roles in mRNA stability and translation regulation.
    • Polyadenylation Signal:
      • A sequence (typically AAUAAA) that signals the addition of a poly-A tail to mRNA, enhancing stability and export from the nucleus.

    Prokaryotic Gene Structure - DNA Signatures

    • Promoter Region:
      • Key Elements: The promoter region in prokaryotes contains two conserved sequences:
        • -10 Box: TATAAT (Pribnow box), located about 10 base pairs upstream of the transcription start site (+1).
        • -35 Box: TTGACA, located about 35 base pairs upstream of the transcription start site.
      • DNA Signature: 5' - TTGACA (N16-18) TATAAT - 3'
    • Ribosome Binding Site (RBS):
      • Shine-Dalgarno Sequence: The Shine-Dalgarno sequence is located 6-10 bases upstream of the start codon (AUG) and aligns the ribosome for translation initiation.
      • DNA Signature: 5' - AGGAGG - 3'
    • Coding Sequence (CDS):
      • Open Reading Frame (ORF): The coding region starts with the start codon (AUG, which codes for methionine) and ends with one of the stop codons (UAG, UAA, UGA).
      • DNA Signature: 5' - ATG (coding region) TAG/TAA/TGA - 3'
    • Terminator Region:
      • Rho-independent: Contains a palindromic sequence that forms a hairpin loop followed by a series of uracils in the RNA transcript (or thymine in DNA).
      • DNA Signature: 5' - GC-rich palindrome (stem-loop) followed by TTTTTT - 3'
      • Rho-dependent: Does not have a specific sequence but relies on the Rho protein to terminate transcription.
    • Operon:
      • Multiple Genes under One Promoter: Operons like the lac operon have several genes (e.g., lacZ, lacY, lacA) transcribed from a single promoter and regulated by a single operator.
      • DNA Signature: 5' - Promoter (TTGACA...TATAAT) Operator Coding Regions (ATG...TAG/TAA/TGA) - 3'

    Eukaryotic Gene Structure - DNA Signatures

    • Promoter Region:
      • TATA Box: Located about 25-30 base pairs upstream of the transcription start site. Other elements such as the CAAT box or GC-rich regions may also be present.
      • DNA Signature: 5' - TATAAAA - 3' - Optional upstream elements like the CAAT Box: 5' - GGCCAATCT - 3'
    • Exons and Introns:
      • Exons: Coding sequences that remain in the mature mRNA after splicing.
      • Introns: Non-coding sequences that are spliced out of pre-mRNA.
      • Splice Site Sequences:
        • 5' Splice Site (Donor Site): 5' - GU - 3' at the start of the intron.
        • 3' Splice Site (Acceptor Site): 5' - AG - 3' at the end of the intron.
        • Branch Point: A conserved "A" about 20-50 nucleotides upstream of the 3' splice site.
      • DNA Signature: 5' - Exon GU (Intron) AG Exon - 3'
    • 5' Untranslated Region (5' UTR):
      • DNA Signature: The 5' UTR varies in length and sequence and contains regulatory elements that influence translation efficiency.
    • Enhancers and Silencers:
      • Enhancers: Distant regulatory elements that can increase transcription.
      • Silencers: Elements that suppress gene expression.
      • DNA Signature: Enhancer and silencer sequences do not have a fixed sequence but often contain binding sites for transcription factors like NF-κB, SP1, or Oct4.
    • Polyadenylation Signal:
      • Poly-A Tail Addition: A signal in the 3' untranslated region (3' UTR) instructs the addition of a poly-A tail to the mRNA transcript.
      • DNA Signature: 5' - AAUAAA - 3'
    • 3' Untranslated Region (3' UTR):
      • DNA Signature: Often variable, the 3' UTR contains sequences that influence mRNA stability, localization, and translation.

    Comparison of DNA Signatures:

    Element Prokaryotic Signature Eukaryotic Signature
    Promoter -35 TTGACA -10 TATAAT TATAAAA (TATA Box)
    Ribosome Binding Site Shine-Dalgarno: AGGAGG No specific sequence, but Kozak sequence: ACCAUGG
    Start Codon ATG ATG
    Terminator Rho-independent: GC-rich + TTTTTT No fixed terminator, polyadenylation: AAUAAA
    Intron/Exon No introns 5' GU...AG 3'
    Poly-A Signal Not present AAUAAA

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Prokaryotic and Eukaryotic Gene Structure PDF

    More Like This

    Untitled Quiz
    6 questions

    Untitled Quiz

    AdoredHealing avatar
    AdoredHealing
    Untitled Quiz
    37 questions

    Untitled Quiz

    WellReceivedSquirrel7948 avatar
    WellReceivedSquirrel7948
    Untitled Quiz
    18 questions

    Untitled Quiz

    RighteousIguana avatar
    RighteousIguana
    Untitled Quiz
    50 questions

    Untitled Quiz

    JoyousSulfur avatar
    JoyousSulfur
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser