mRNA Transport and Degradation in Eukaryotes
48 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the role of deadenylation in eukaryotic mRNA degradation?

  • It initiates the degradation of mRNA. (correct)
  • It enhances mRNA stability.
  • It facilitates the transport of mRNA to the ribosome.
  • It prevents localization of mRNA.

    • Which proteins are identified as auxiliary exporters specifically in yeast?

  • Arx1 and Mex67
  • Mtr2 and Arx1
  • Mex67 and Mtr2 (correct)
  • Ribosomal proteins and Arx1

    • How is the half-life of mRNAs influenced?

  • By the ribosomal binding sites present.
  • By the presence of auxiliary exporters.
  • By specific sequences or structures within the mRNA. (correct)
  • By their localization within the nucleus.

    • What does the quality control verification process for mRNAs involve?

    <p>Checking the stability and localization of the mRNAs.</p> Signup and view all the answers

    What are export adaptors involved in?

    <p>Facilitating mRNA transport.</p> Signup and view all the answers

    What challenges did eukaryotic evolution face regarding mRNA transport?

    <p>Solving export-related issues.</p> Signup and view all the answers

    The stabilization of mRNAs depends on which of the following?

    <p>Specific sequences or structures within the mRNAs.</p> Signup and view all the answers

    Which component is NOT typically involved in mRNA transport mechanisms?

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

    What is the predominant mechanism for mRNA localization involving motor proteins?

    <p>Active transport along cytoskeletal tracks</p> Signup and view all the answers

    Which of the following components is NOT required for active mRNA transport?

    <p>Energy source for motor proteins</p> Signup and view all the answers

    What is the first step in the processes of localization, translation, and degradation?

    <p>Localization must occur before translation</p> Signup and view all the answers

    Which proteins are known to block AHS1 mRNA translation during transport?

    <p>Puf6p and Khd1p</p> Signup and view all the answers

    The loss of localization of which protein is associated with Fragile X syndrome?

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

    What role does FMRP play in neuronal cells?

    <p>Regulating local translation of mRNAs</p> Signup and view all the answers

    What role does localization play in the development of embryos?

    <p>It assigns developmental fates to cells in different regions</p> Signup and view all the answers

    How does RNA repression during transport occur?

    <p>By blocking the binding of ribosomal subunits</p> Signup and view all the answers

    Which of the following describes the second mechanism of mRNA localization?

    <p>Freely diffusible mRNA becoming trapped at the site of translation</p> Signup and view all the answers

    In the context of mRNA localization, what is the primary function of trans-factors?

    <p>To attach mRNA to motor proteins</p> Signup and view all the answers

    What mechanism is used by cells that divide asymmetrically to manage protein factors?

    <p>Segregation of protein factors to one daughter cell</p> Signup and view all the answers

    What effect does the absence of functional FMRP have on mRNA localization?

    <p>Causes loss of proper localization</p> Signup and view all the answers

    What is required for the localization of certain mRNAs?

    <p>Cis-elements on the target mRNA and trans-factors</p> Signup and view all the answers

    In polarized cell types, what is the primary function of mRNA localization?

    <p>To establish cellular compartments</p> Signup and view all the answers

    What must occur to unlocalized mRNAs in order for effective localization to happen?

    <p>They must be degraded or repressed</p> Signup and view all the answers

    What is one key aspect of mRNA translation in oocytes?

    <p>mRNA translation is delayed until specific sites are reached</p> Signup and view all the answers

    What is the role of AU-rich elements (AREs) in mRNA decay?

    <p>They accelerate mRNA decay by recruiting degradation machinery.</p> Signup and view all the answers

    How do stabilizing elements (SEs) affect mRNA decay?

    <p>They contain stabilizing sequences that reduce mRNA decay.</p> Signup and view all the answers

    What mechanisms do DE-binding proteins utilize to promote mRNA degradation?

    <p>They interact with decay machinery components for degradation.</p> Signup and view all the answers

    Which activity is stimulated by the interaction with exosomes?

    <p>Exonuclease activity</p> Signup and view all the answers

    What role does the RNA helicase play in mRNA quality control?

    <p>It unwinds secondary structures and removes RBPs</p> Signup and view all the answers

    What is the function of the TRAMP complex?

    <p>It targets aberrant RNAs to the exosome for degradation.</p> Signup and view all the answers

    What happens to improperly processed transcripts in the nucleus?

    <p>They are degraded and do not leave the transcription site.</p> Signup and view all the answers

    What is the function of a non-canonical poly (A) polymerase in mRNA processing?

    <p>It adds a poly (A) tail to the target substrate</p> Signup and view all the answers

    What distinguishes SEs from DEs in mRNA stability?

    <p>SEs contain sequences that help to preserve mRNA stability.</p> Signup and view all the answers

    Which condition is required for a non-sense mutation to be recognized in mRNA?

    <p>Presence of a splice junction</p> Signup and view all the answers

    Which mechanism involves Upf proteins and targets mRNA for rapid decay?

    <p>Non-sense termination decay</p> Signup and view all the answers

    What component is essential for the destruction of aberrant RNAs in the exosome?

    <p>3'–5' exonuclease activity.</p> Signup and view all the answers

    In what way do ARE-BPs function in relation to AU-rich elements?

    <p>They prevent ARE from causing mRNA destabilization.</p> Signup and view all the answers

    What produces toxic C-truncated polypeptides in cells?

    <p>Nonsense mutations leading to premature termination</p> Signup and view all the answers

    What structures help in distinguishing PTCs from normal termination codons?

    <p>Presence of downstream exon junction complexes</p> Signup and view all the answers

    Which of the following indicates a too long 3' UTR in mRNA?

    <p>Presence of abnormal termination codons</p> Signup and view all the answers

    What is the primary role of the nuclear pore complex (NPC)?

    <p>To facilitate the movement of mRNP through the nuclear membrane</p> Signup and view all the answers

    Which of the following describes the structure that mRNA encounters when passing through the nuclear pore?

    <p>A mesh of hydrophobic FG repeat nucleoporins</p> Signup and view all the answers

    What prevents the backsliding of mRNP into the nucleus?

    <p>The activation of DBP5 in the cytoplasm</p> Signup and view all the answers

    How many nuclear pores are typically found in a vertebrate somatic cell?

    <p>1,000 to 10,000</p> Signup and view all the answers

    What is the significance of the brush-like structure formed by FG repeats in nucleoporins?

    <p>It provides binding sites for proteins involved in nuclear export</p> Signup and view all the answers

    What role do mRNA export adaptors play after mRNP has exited the nucleus?

    <p>They are shuttled back into the nucleus for further use</p> Signup and view all the answers

    What happens to TAP when mRNP reaches the cytoplasm?

    <p>It is removed by DBP5</p> Signup and view all the answers

    What determines how frequently a specific polypeptide will be translated from mRNA?

    <p>The sequence and regulation of the mRNA</p> Signup and view all the answers

    Study Notes

    mRNA Processing and Transport

    • mRNA nucleo-cytoplasmic transport involves the movement of mRNA from the nucleus to the cytoplasm.
    • mRNA stability and localization are critical for cellular function.
    • Eukaryotic mRNAs undergo quality control to ensure their integrity.
    • mRNA stability is influenced by specific sequences or structures within the mRNA molecule.
    • Deadenylation-dependent degradation pathways regulate mRNA half-lives, which are controlled by various sequences.
    • mRNAs are often associated with proteins to form mRNPs, which facilitates their movement and localization.

    Export Mechanisms

    • mRNA export from the nucleus is facilitated by the nuclear pore complex (NPC).
    • Proteins like TREX and SR proteins are involved in the transport.
    • The process involves several major steps.
    • Export adaptors and receptors bind to the mRNA.
    • The mRNP is processed to become export-competent.
    • The mRNP enters the NPC.
    • The RNA is disassembled after export.
    • Additional proteins help with shuttling the RNA components back into the nucleus.

    RNA-Checking for Defects

    • Errors in mRNA processing can be identified by the RNA surveillance system.
    • Aberrant or misfolded RNAs are tagged and targeted for degradation.
    • The exosome and TRAMP complex are involved in this process, targeting these errors.
    • Defects are addressed after processing and before the mRNA enters the cytoplasm.

    mRNA Degradation Pathways

    • mRNA decay pathways are influenced by sequences.
    • Deadenylation plays a key role in eukaryotic mRNA degradation.
    • Removal of the poly(A) tail is often followed by decapping events and 5'-3' exonuclease digestion.
    • Other degradation pathways, including sequence-specific cleavages, are also possible.
    • MicroRNAs (miRNAs) also target specific mRNA for degradation.
    • Half-lives of mRNAs vary with the mRNAs.

    mRNA Localization

    • Some mRNAs are translated at specific cellular locations.
    • Localization requires cis-elements within the mRNA molecule.
    • Trans-acting factors assist in mRNA localization.
    • Mechanisms for active transport of mRNAs exist.
    • Translation is often repressed until the mRNA reaches its target location.

    Quality Control of mRNA Translation

    • Non-sense termination decay, Nonstop decay, and No-go decay are three types of mRNA surveillance.
    • These pathways detect and target faulty mRNAs that potentially lead to non-functional proteins.
    • The mRNAs are often degraded rather than exported.

    Interconnection of Mechanisms

    • The processes of mRNA localization, translation, and degradation are interrelated.

    Studying That Suits You

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

    Quiz Team

    Related Documents

    UC Biologia Molecular Past Paper 2024-2025 - Part 2, Module 4

    Description

    Explore the intricate processes of mRNA transport, localization, and degradation in eukaryotic cells. This quiz covers key mechanisms, proteins involved, and the evolutionary challenges faced by eukaryotes regarding mRNA. Test your knowledge on how these processes influence mRNA half-life and developmental roles.

    More Like This

    mRNA Processing and Transport
    262 questions

    mRNA Processing and Transport

    SociableMossAgate avatar
    SociableMossAgate
    Biology Quiz on mRNA and Mutations
    20 questions

    Biology Quiz on mRNA and Mutations

    LuminousGadolinium avatar
    LuminousGadolinium
    Biology Flashcards: mRNA, tRNA, rRNA Definitions
    11 questions

    Biology Flashcards: mRNA, tRNA, rRNA Definitions

    VirtuousConflict avatar
    VirtuousConflict
    BIOL200 RNA Processing II and Transport
    29 questions

    BIOL200 RNA Processing II and Transport

    CongenialCarnelian9331 avatar
    CongenialCarnelian9331
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser