T.14 mRNA
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Questions and Answers

What is the primary function of RNA polymerase during transcription?

  • To translate the RNA sequence into a polypeptide chain
  • To polyadenylate the 3' end of the RNA
  • To add a cap to the 5' end of the RNA
  • To read the DNA template and match incoming nucleotides (correct)
  • What is the primary function of the cap structure at the 5' end of the RNA?

  • To stabilize the RNA and prevent degradation
  • To recruit ribosomes for translation
  • To enhance translation efficiency
  • All of the above (correct)
  • What is the purpose of polyadenylation?

  • To stabilize the RNA and enhance translation efficiency (correct)
  • To add a cap to the 5' end of the RNA
  • To transcribe the DNA template into an RNA molecule
  • To initiate translation by binding ribosomes to the mRNA
  • What is the first step in the translation process?

    <p>Initiation: Ribosome binds to the mRNA and reads the start codon</p> Signup and view all the answers

    What is the role of the ribosome in the translation process?

    <p>To bind to the mRNA and read the codons</p> Signup and view all the answers

    What is the final product of the translation process?

    <p>A polypeptide chain</p> Signup and view all the answers

    What is the result of the desamination of adenines in tRNA?

    <p>A change in the identity of the base.</p> Signup and view all the answers

    What is the function of the snoRNP C/D in archaea?

    <p>Guiding the methylation of a nucleotide in each site.</p> Signup and view all the answers

    What is the role of Nop5, Nop56, and Nop58 proteins in the snoRNP C/D?

    <p>Recognizing the C and C' D and D' boxes.</p> Signup and view all the answers

    What is the function of fibrillarin (Fib) in the snoRNP C/D?

    <p>Interacting with the D and D' boxes.</p> Signup and view all the answers

    What is the structure of the snoRNP H/ACA?

    <p>A pseudosymmetric architecture.</p> Signup and view all the answers

    What is the role of Cbf5 in the snoRNP H/ACA?

    <p>Positioning the pseudouridylation pocket.</p> Signup and view all the answers

    What is the proposed structure of the snoRNP H/ACA?

    <p>A bipartite structure with a copy of the H/ACA protein core assembled on each hairpin motif of the snoRNA</p> Signup and view all the answers

    What is the term used to describe the correction of RNA sequences?

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

    What is the result of desaminating the citosine in the triplete CAA?

    <p>A triplete UAA that causes a premature stop</p> Signup and view all the answers

    What type of modification can occur in the RNA sequence of some organisms?

    <p>All of the above</p> Signup and view all the answers

    What is the consequence of desaminating the citosine in the triplete CAA?

    <p>A premature stop in the protein sequence</p> Signup and view all the answers

    What is the role of the citidina-desaminasa and adenosina desaminasa enzymes?

    <p>To modify the RNA sequence through deamination</p> Signup and view all the answers

    What is the consequence of a deficiency or hyperactivity in the adenosina desaminasa enzyme?

    <p>Various human diseases, such as epilepsy, cancer, and depression</p> Signup and view all the answers

    Where are the majority of the targets of RNA editing found in invertebrates and vertebrates?

    <p>In the nervous system</p> Signup and view all the answers

    What is the current understanding of the biofisical and physiological changes caused by A to I editing in invertebrates and vertebrates?

    <p>The changes are almost completely unknown</p> Signup and view all the answers

    What is the difference between the RNA editing process in invertebrates and vertebrates?

    <p>The RNA editing process is completely different in invertebrates and vertebrates</p> Signup and view all the answers

    What is the main reason why multiple proteins can be obtained from a single gene?

    <p>Post-transcriptional modifications of mRNAs</p> Signup and view all the answers

    What is the consequence of desamination of a C to a U in a codon CAA in the intestine?

    <p>The protein is truncated and lacks 2410 amino acids</p> Signup and view all the answers

    What is the purpose of writers and erasers in post-transcriptional modifications of mRNAs?

    <p>To methylate adenines in specific positions</p> Signup and view all the answers

    What is the effect of methylation in position 1 of adenine on hydrogen bonding?

    <p>It introduces a positive charge that blocks hydrogen bonding</p> Signup and view all the answers

    What determines the fate of a messenger RNA in the cytoplasm?

    <p>The degree and position of methylation</p> Signup and view all the answers

    What is the consequence of having multiple forms of apolipoprotein in different tissues?

    <p>The protein has different functions in different tissues</p> Signup and view all the answers

    What is the role of readers in post-transcriptional modifications of mRNAs?

    <p>To determine the functionality of the modification</p> Signup and view all the answers

    What is the main difference between the apolipoprotein in the liver and intestine?

    <p>The protein is truncated in the intestine</p> Signup and view all the answers

    What is the effect of methylation in position 6 of adenine on hydrogen bonding?

    <p>It has no effect on hydrogen bonding</p> Signup and view all the answers

    What is the purpose of metylations in the life of messenger RNAs?

    <p>To influence the life of messengers</p> Signup and view all the answers

    What is the primary role of metilations in mRNA?

    <p>To serve as a signal for protein binding, affecting translation and degradation</p> Signup and view all the answers

    What is the term used to describe the set of modifications in mRNA?

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

    What is the purpose of the co-transcriptional addition of metilations to mRNA?

    <p>To create a specific imprint that conditions the mRNA's fate in the cytoplasm</p> Signup and view all the answers

    What is the fate of mRNA molecules that are not translated into protein?

    <p>They are stored in cytoplasmic organelles called P-bodies or stress granules</p> Signup and view all the answers

    What is the function of the proteins that recognize metilations in mRNA?

    <p>To alter the stability or translatability of the mRNA</p> Signup and view all the answers

    Why are most metilations in mRNA found outside of the reading frame?

    <p>Because they do not have a direct consequence on base pairing</p> Signup and view all the answers

    What is the result of having different patterns of metilations in mRNA molecules?

    <p>mRNA molecules with different patterns of metilations have different fates in the cytoplasm</p> Signup and view all the answers

    What is the role of metiltransferases in the epitranscriptomics process?

    <p>To add metilations to mRNA molecules during transcription</p> Signup and view all the answers

    What is the main difference between DNA replication and epitranscriptomics?

    <p>DNA replication replicates the sequence, while epitranscriptomics introduces modifications</p> Signup and view all the answers

    What is the relationship between the pattern of metilations and the translation of mRNA into protein?

    <p>The pattern of metilations can make mRNA molecules more or less translatable</p> Signup and view all the answers

    Study Notes

    mRNA Structure and Synthesis

    Transcription

    • Process of creating a complementary RNA copy from a DNA template
    • Initiated when an enzyme called RNA polymerase binds to the DNA template
    • RNA polymerase reads the DNA template and matches the incoming nucleotides to the base pairing rules (A-T, G-C)
    • The resulting RNA molecule is complementary to the DNA template

    Capping

    • Addition of a specialized structure called a cap to the 5' end of the newly synthesized RNA
    • The cap is composed of 7-methylguanosine (m7G) and is attached to the first nucleotide of the RNA
    • Functions:
      • Protects the RNA from degradation
      • Helps to recruit ribosomes for translation
      • Enhances translation efficiency

    Polyadenylation

    • Process of adding a long string of adenine nucleotides (poly(A) tail) to the 3' end of the RNA
    • Occurs after transcription is complete
    • Functions:
      • Stabilizes the RNA and prevents degradation
      • Enhances translation efficiency
      • Helps to transport the RNA out of the nucleus

    Translation

    • Process of using the mRNA sequence to build a polypeptide chain
    • Occurs in the cytoplasm
    • Steps:
      1. Initiation: Ribosome binds to the mRNA and reads the start codon
      2. Elongation: Amino acids are brought to the ribosome and added to the growing polypeptide chain
      3. Termination: The ribosome reaches the stop codon and releases the completed polypeptide chain

    Splicing

    • Process of removing introns (non-coding regions) and joining exons (coding regions) to form a mature RNA
    • Occurs in the nucleus
    • Steps:
      1. Recognition: Spliceosomes recognize the intron-exon boundaries
      2. Cleavage: The intron is cleaved from the RNA
      3. Ligation: The exons are joined together to form a mature RNA

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    Description

    This quiz covers the process of creating a complementary RNA copy from a DNA template, including transcription, capping, polyadenylation, translation, and splicing. Learn about the functions of each step and how they contribute to the formation of a mature RNA.

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