9!!Molecular Mechanisms of Disease Quiz
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Questions and Answers

What is the primary role of exons in mRNA processing?

  • They consist primarily of conserved splice site sequences.
  • They are sequences that are removed before the RNA becomes functional.
  • They are parts of the gene that contribute to the mature RNA product. (correct)
  • They are intervening sequences that develop into noncoding RNA.

    • Which of the following best describes introns?

  • They are responsible for the splicing process, facilitating exon recruitment.
  • They are sequences removed during mRNA processing and account for ~95% of pre-RNA. (correct)
  • They contain conserved sequences necessary for the translation of RNA.
  • They are crucial for protein coding and are included in the mature RNA.

    • What is the significance of the 5’ and 3’ splice sites?

  • They are the locations where ribosomal subunits attach to mRNA.
  • They are highly conserved sequences that signal where splicing occurs. (correct)
  • They are essential for initiating transcription of the RNA.
  • They represent the boundaries of pseudogenes within the genomic sequence.

    • What role do exonic splicing enhancers (ESE) play in splicing?

    <p>They help recruit snRNPs to the splicing machinery.</p> Signup and view all the answers

    Approximately what percentage of human inherited diseases may result from splicing errors?

    <p>15-30%</p> Signup and view all the answers

    What is the primary role of RNA polymerase II in transcription?

    <p>To synthesize complementary RNA from a DNA template</p> Signup and view all the answers

    Which component is NOT required for the process of translation?

    <p>Transcription factors</p> Signup and view all the answers

    What is the fate of the primary transcript known as pre-mRNA once it is synthesized?

    <p>It undergoes processing before becoming mature mRNA</p> Signup and view all the answers

    What is NOT a feature of heterogeneous nuclear RNA (hnRNA)?

    <p>It is composed of mature mRNA only</p> Signup and view all the answers

    Which processing step involves adding a protective cap to the 5' end of pre-mRNA?

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

    What is produced at the end of the transcription process?

    <p>Messenger RNA (mRNA)</p> Signup and view all the answers

    Which of the following is NOT required for translation?

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

    What is the primary function of the C-terminal domain (CTD) of RNA polymerase during transcription?

    <p>To organize factors for pre-mRNA processing</p> Signup and view all the answers

    Which statement accurately describes heterogeneous nuclear RNA (hnRNA)?

    <p>It serves as a precursor RNA that is short-lived.</p> Signup and view all the answers

    Which of the following processing events occurs to pre-mRNA?

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

    What is the primary function of the spliceosome during mRNA processing?

    <p>To perform RNA splicing</p> Signup and view all the answers

    Which component of the spliceosome is responsible for the cleavage of the 5’ splice site?

    <p>U6 snRNA</p> Signup and view all the answers

    What role does U2AF play in the splicing process?

    <p>It aids in the attraction of U2 snRNP</p> Signup and view all the answers

    How does the presence of U4/U6 snRNPs influence the splicing of pre-mRNA?

    <p>They form a stable duplex before U6 displacement</p> Signup and view all the answers

    What is the significance of alternative splicing in gene expression?

    <p>It allows a single gene to code for multiple polypeptides</p> Signup and view all the answers

    What is the starting material required for the transcription process?

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

    Which of the following is a required component for translation?

    <p>Ribosomal RNA (rRNA)</p> Signup and view all the answers

    What is the end product of the translation process?

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

    What type of RNA is generated during the process of transcription?

    <p>Messenger RNA (mRNA)</p> Signup and view all the answers

    What is the primary role of the C-terminal domain (CTD) of RNA polymerase during transcription?

    <p>To organize factors for pre-mRNA processing</p> Signup and view all the answers

    Where are tRNA genes primarily located within the genome?

    <p>In small clusters scattered around the genome</p> Signup and view all the answers

    What type of RNA polymerase is responsible for transcribing tRNAs?

    <p>RNA polymerase III</p> Signup and view all the answers

    What role do tRNA isoacceptors play in protein synthesis?

    <p>They decode mRNA codons into amino acids</p> Signup and view all the answers

    What is referred to as 'codon degeneracy' in the genetic code?

    <p>The ability to have one amino acid coded by multiple codons</p> Signup and view all the answers

    What is the role of small nuclear ribonuclear proteins (snRNPs) in mRNA processing?

    <p>They assist in the recruitment of proteins necessary for splicing.</p> Signup and view all the answers

    Which of the following statements accurately reflects the characteristics of introns?

    <p>They are noncoding sequences intervening between exons.</p> Signup and view all the answers

    What specific sequence marks the 5' splice site in pre-mRNA?

    <p>G/GU</p> Signup and view all the answers

    What is the estimated percentage of human inherited diseases that may arise from splicing errors?

    <p>15-30%</p> Signup and view all the answers

    What is the function of exonic splicing enhancers (ESE)?

    <p>They recruit snRNPs to facilitate splicing.</p> Signup and view all the answers

    What is the main role of U1 snRNP during RNA splicing?

    <p>It attaches to the 5’ splice site.</p> Signup and view all the answers

    Which molecule is primarily responsible for catalyzing the first cleavage reaction during RNA splicing?

    <p>U6 snRNA</p> Signup and view all the answers

    What is the function of the U2AF protein in the splicing process?

    <p>To bind the branch point sequence</p> Signup and view all the answers

    What occurs during the second cleavage reaction in RNA splicing?

    <p>Exons are ligated and the lariat intron is excised</p> Signup and view all the answers

    Study Notes

    Molecular Mechanisms of Disease

    • HSS2305: Course focusing on molecular mechanisms of disease.
    • Covered lecture topics include gene transcription and translation.

    Gene Transcription and Translation

    • The process of synthesizing complementary RNA from a DNA template in the nucleus is transcription.
    • Starting material for transcription is DNA.
    • RNA polymerase II and transcription factors are essential for transcription machinery.
    • Messenger RNA (mRNA) is the end product of transcription.
    • Translation is the synthesis of proteins in the cytoplasm using information encoded in mRNA.
    • The starting material for translation is mRNA.
    • Ribosomal RNA (rRNA), ribosomal proteins, and transfer RNA (tRNA) are required for translation machinery.
    • The end product of translation is a polypeptide.

    Transcription - Processing mRNA

    • Primary transcript is also referred to as pre-mRNA or heterogeneous nuclear RNA (hnRNA).
    • Primary transcripts are equivalent in length to the whole DNA being transcribed.
    • Such transcripts are always associated with proteins.
    • They have a short life span.
    • 5' Caps:
      • Capping enzymes are recruited by the phosphorylated CTD (Ser-5 phosphorylation by TFIIH).
      • Prevents digestion of the 5` end from exonucleases.
      • Aids in the transport of mRNA out of the nucleus.
      • Important in initiating translation.
    • 3' poly(A) tail:
      • Poly(A) tail enzymes are recruited by phosphorylated CTD.
      • Protects mRNA from premature degradation by exonucleases.
    • RNA splicing:
      • Exons are parts of the gene that contribute to mature RNA product.
      • Introns are intervening sequences, noncoding segments not included in mature RNA (about 95% of pre-RNA).
      • Splice sites and exon-intron boundary sequences, typically G/GU and AG/G respectively, are highly conserved.
      • Splicing involves breaking at the 5 and 3 ends.
      • Small nuclear ribonuclear proteins (snRNPs), consist of small nuclear RNAs (snRNAs), and associated proteins, are critical to splicing.
      • U1, U2, U4, U5, and U6 snRNAs are examples of snRNA involved in splicing.

    Transcription - rRNA and tRNA

    • DNA transcribes to produce various RNA types, including mRNA, rRNA, and tRNA.
    • rRNA (ribosomal RNA) is a crucial component of ribosomes (80% of a cell's RNA).
    • rRNA comprises four different ribosomal RNAs (rRNAs): 18S, 5.8S, 28S, and 5S.
    • rRNA transcription takes place in nucleoli in eukaryotic cells.
    • rDNA clusters which contain genes encoding rRNA are arranged in tandem.
    • rRNA transcription pattern is like a Christmas tree.
    • tRNA (transfer RNA) links mRNA codons to amino acids during polypeptide synthesis.
    • tRNA genes are scattered throughout the genome, arranged in tandem.
    • tRNA precursors undergo modifications
    • Nontranscribed spacers (NTS) separate units in such clusters.

    Translation

    • rRNA is transcribed by RNA pol I.
    • tRNA is transcribed by RNA pol III.
    • Codons are nucleotide triplets that match with specific amino acids.
    • Anticodons are tRNA sequences that complement mRNA codons.
    • Codon degeneracy reduces the effect of DNA mutations
    • Wobble pairing is when the third position of a codon-anticodon pairing is not crucial.
    • Aminoacyl-tRNA synthetases (AARS) link amino acids to tRNAs.
    • Translation initiation is a multi-step process that includes the binding of various initiation factors to the ribosomal subunit.
    • Translation elongation and termination are progressive processes involving addition and release of amino acids and stop codons.
    • Ribosomes provide the locations where these processes occur, and have three sites where tRNAs reside.
    • Polyribosomes (polysomes) are multiple ribosomes on a single mRNA that increase the rate of protein synthesis.

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    HSS2305A - 2024 Lecture 9 PDF

    Description

    This quiz covers essential concepts related to the molecular mechanisms of disease, particularly focusing on gene transcription and translation. It delves into the roles of various RNA types and the machinery involved in these processes. Test your knowledge on the translation and transcription processes, including the key components necessary for each.

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