DNA Damage and Repair Mechanisms Quiz
63 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 constitutes DNA damage?

  • A change in the base pair sequence
  • Chemical alteration to DNA (correct)
  • An increase in the amount of DNA
  • A result of DNA replication errors

    • Which of the following constitutes error-prone DNA repair mechanisms?

  • Repair that is always advantageous for the organism
  • Repair that introduces no changes
  • Repair that ensures no mutations occur
  • Repair that can promote genetic variation (correct)

    • Which environmental agent primarily causes the formation of thymine dimers?

  • Ionizing radiation
  • Chemical mutagens
  • UV light (correct)
  • Heat from fire

    • What type of DNA damage is associated with base analogs?

    <p>Incorrect base pairing due to molecular similarity</p> Signup and view all the answers

    What effect do pyrimidine dimers have on DNA structure?

    <p>They cause distortion and interference with replication</p> Signup and view all the answers

    Which chemical agent can cause a base change such as cytosine to uracil?

    <p>Nitrous acid</p> Signup and view all the answers

    What is the primary effect of intercalating agents on DNA?

    <p>They physically disrupt the base stacking of DNA</p> Signup and view all the answers

    What type of mutation can result from point mutations?

    <p>Substitution mutations</p> Signup and view all the answers

    What is the helix width of B-DNA?

    <p>2.4 nm</p> Signup and view all the answers

    How many base pairs are there per turn in Z-DNA?

    <p>12</p> Signup and view all the answers

    Which characteristic differentiates A-DNA from B-DNA?

    <p>Base tilt of 19°</p> Signup and view all the answers

    What is the twist of B-DNA in terms of base pairs per turn?

    <p>10 bp/turn</p> Signup and view all the answers

    Which statement is true about the major groove of B-DNA compared to A-DNA?

    <p>B-DNA's major groove is wider and deeper.</p> Signup and view all the answers

    What is the propeller twist angle of A-DNA?

    <p>18°</p> Signup and view all the answers

    Which type of topoisomerase creates transient single-strand breaks?

    <p>Type I</p> Signup and view all the answers

    What property is characteristic of Z-DNA compared to B-DNA?

    <p>Left-handed helical structure</p> Signup and view all the answers

    What happens when the top of the helix is twisted counterclockwise?

    <p>The twist decreases and becomes underwound</p> Signup and view all the answers

    Which type of supercoiling occurs in underwound right-handed DNA?

    <p>Negative supercoiling</p> Signup and view all the answers

    Which structural feature of B-DNA aids in its stability in aqueous environments?

    <p>Major groove with larger distances between phosphates</p> Signup and view all the answers

    Which topoisomerase type requires ATP to function?

    <p>Type II</p> Signup and view all the answers

    How does the base pair spacing in A-DNA compare to that in B-DNA?

    <p>A-DNA has shorter base pair spacing.</p> Signup and view all the answers

    Which feature indicates that Z-DNA is a temporary structure?

    <p>Its energy level being higher than B-DNA</p> Signup and view all the answers

    What is the result of introducing supercoiling to the DNA structure?

    <p>It relieves tension in the DNA structure</p> Signup and view all the answers

    Which of the following statements is true about Type IB topoisomerases?

    <p>Relaxes both negative and positive supercoiling</p> Signup and view all the answers

    What is a significant aspect of the helical structure of A-DNA?

    <p>More base pairs per turn than B-DNA</p> Signup and view all the answers

    How does the twist of a DNA helix affect its overall structure?

    <p>A lower twist generates supercoiling</p> Signup and view all the answers

    What is the primary function of topoisomerases?

    <p>To alter DNA coiling and relieve tension</p> Signup and view all the answers

    If the twist of a DNA helix is decreased, what is likely to occur?

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

    Which structural feature is unique to RNA and not typically found in DNA?

    <p>Formation of hairpin structures</p> Signup and view all the answers

    What stabilizes the structure of RNA?

    <p>Base stacking, base pairing, and ionic interactions</p> Signup and view all the answers

    What describes a bulge in RNA structure?

    <p>A loop that does not participate in base pairing</p> Signup and view all the answers

    Which of the following represents a characteristic of pseudoknots in RNA?

    <p>Can undergo conformational changes</p> Signup and view all the answers

    Which base pairing happens less frequently in RNA compared to conventional pairs?

    <p>Unconventional base pairing</p> Signup and view all the answers

    Which structural element of RNA involves single or multiple bases protruding from paired structures?

    <p>Internal loop</p> Signup and view all the answers

    What differentiates RNA from DNA in terms of lifespan?

    <p>RNA has a shorter lifespan than DNA</p> Signup and view all the answers

    Which of the following is a function of RNA's ability to self base-pair?

    <p>Engaging in enzymatic reactions</p> Signup and view all the answers

    How does RNA's structural flexibility impact its function?

    <p>It allows RNA to adopt multiple conformations, influencing function</p> Signup and view all the answers

    Which statement correctly contrasts RNA with DNA?

    <p>RNA can self-base pair while DNA does not</p> Signup and view all the answers

    What is the primary function of topoisomerase during DNA replication?

    <p>To regulate supercoiling</p> Signup and view all the answers

    Which enzyme is responsible for introducing negative supercoiling in bacterial DNA?

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

    What initial substrate is used in the synthesis of purine nucleotides?

    <p>Ribose-5-Phosphate</p> Signup and view all the answers

    What happens when there is an imbalance in nucleotide concentrations?

    <p>Polymerase may stall or make errors</p> Signup and view all the answers

    Which of the following feedback mechanisms occurs to halt purine synthesis?

    <p>AMP inhibits allosterically at PRPP formation</p> Signup and view all the answers

    What is the immediate product after the removal of a phosphate from AMP during purine degradation?

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

    What is the final product of purine metabolism that is excreted from the body?

    <p>Uric Acid</p> Signup and view all the answers

    Which reaction involves the conversion of GTP to GDP?

    <p>GMP synthesis from XMP</p> Signup and view all the answers

    What regulates the availability of purine nucleotides for further synthesis?

    <p>Allosteric feedback mechanisms</p> Signup and view all the answers

    Which kinase facilitates the conversion of ADP to ATP?

    <p>Adenylate kinase</p> Signup and view all the answers

    What role does the sigma subunit of RNA polymerase play during transcription initiation?

    <p>It recognizes and binds to specific promoter sequences.</p> Signup and view all the answers

    Which of the following is NOT a characteristic of prokaryotic RNA polymerase?

    <p>It requires additional transcription factors at all times.</p> Signup and view all the answers

    How does intrinsic termination of transcription occur in bacteria?

    <p>Via the formation of a stable hairpin loop in the RNA transcript.</p> Signup and view all the answers

    What happens to the sigma subunit of RNA polymerase during elongation?

    <p>It is released once the initial RNA transcript is synthesized.</p> Signup and view all the answers

    Which factor is crucial for transcription termination by Rho-dependent mechanisms?

    <p>Detection of a rut site on the RNA transcript.</p> Signup and view all the answers

    What are the consensus elements found in bacterial promoters?

    <p>-10 region and -35 region.</p> Signup and view all the answers

    During transcription elongation, what is the preferred type of nucleotide triphosphate (NTP) at the initiation site?

    <p>ATP or GTP</p> Signup and view all the answers

    What structural role does the omega subunit of the RNA polymerase core enzyme serve?

    <p>It is likely structural and non-essential.</p> Signup and view all the answers

    How does transcription in prokaryotic cells differ from transcription in eukaryotic cells?

    <p>Transcription and translation can occur simultaneously in prokaryotes.</p> Signup and view all the answers

    What happens during the 'melted' state of the promoter complex?

    <p>DNA strand separation occurs, increasing binding affinity.</p> Signup and view all the answers

    What is the usual error rate observed during prokaryotic transcription?

    <p>1 error in every 10,000 nucleotides transcribed</p> Signup and view all the answers

    Which statement best describes the function of topoisomerase during bacterial transcription?

    <p>It relieves supercoiling in the DNA helix.</p> Signup and view all the answers

    In which of the following situations would a sigma factor like σ24 be utilized?

    <p>During heat stress response.</p> Signup and view all the answers

    What is the primary role of the transcription start site in bacterial transcription?

    <p>It is where RNA polymerase begins synthesizing RNA.</p> Signup and view all the answers

    Signup and view all the answers

    Study Notes

    Nucleic Acid Structure - Learning Outcomes

    • Compare and contrast the different helical structures formed by DNA.
      • DNA double helix (in aqueous solution) is 18 Å across.
        • Each base is 3.4 Å thick with a 2.6 Å gap, allowing water to enter
        • The gap must be closed; pressing down is energetically unfavorable.
        • Must stagger, which creates open surface area.
        • The turning motion maximizes surface area and is energetically favorable.
      • B-DNA:
        • Right-handed helix
        • Helix width = 2.4 nm
        • Base pair spacing = 0.34 nm
        • One turn = 3.4 nm (10 base pairs per turn)
        • Major and minor grooves
        • Major groove wider and deeper, base tilt = -1.2°
      • A-DNA:
        • Right-handed helix (longer than B-DNA)
        • Helix width = 2.6 nm
        • Base pair spacing = 0.23 nm
        • One turn = 2.5 nm (11 bases per turn)
        • Much larger major groove
        • Base tilt = 19°
        • Propeller twist = 18° (slightly more than B-DNA)
        • Higher energy than B-DNA
      • Z-DNA:
        • Left-handed helix
        • 12 bp/turn (1 more than A-DNA, 2 more than B-DNA)
        • Higher energy than B-DNA
    • Describe the forces that stabilize nucleic acid structure.
      • Base stacking:
        • GC bonds stronger than AT bonds
        • AT bonds worse at forming base stacks
        • Induced dipole + partial charge interactions between base rings
      • Base Pairing
      • GC/GC pairings more stable than CG/CG - Important for determining specific DNA sequences
      • Advantages over H2O pairing is in cooperativity (forming double-helix vs separate bonds with water).
    • Predict the effect of intrinsic and environmental factors on stability of a DNA double helix.
      • Higher % GC content correlates with a higher melting point due to stronger bonds.
      • Higher DNA length produces a higher melting point.
      • High polarity solvents lead to higher melting points.
      • Concentration and presence of ions affect melting point.

    Nucleic Acid Structure - Learning Outcomes (cont'd)

    • Explain how and why individual elements of DNA structure can deviate from the average structure.

      • Intra-base pair coordinates (between two bases) influences wobble/flexibility.
        • Shear, buckle, stretch, propeller, stagger, opening
        • Shift, tilt, slide, roll, rise, twist

    • Describe the types of secondary and tertiary structures formed by RNA.

      • RNA is less stable than DNA.
      • RNA contains ribose, DNA deoxyribose.
      • Hydroxide in RNA makes ribose molecules more reactive.
      • RNA = uracil, DNA = thymine
      • RNA = single-stranded, DNA = double-stranded
      • RNA can self-base pair, DNA typically cannot.

    Nucleic Acid Structure - Learning Outcomes (cont'd)

    • How do RNA structure types differ from DNA structure?
      • RNA forms many different secondary structures.
      • RNA uses different types of base pairing to stabilize secondary structure due to reactive ribose.
      • RNA often folds into complex 3D structures.
      • RNA often has functions in protein synthesis.

    Studying That Suits You

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

    Quiz Team

    Related Documents

    Biochem 3382 Exam Prep PDF

    Description

    Test your knowledge on DNA damage, the various causes of mutations, and repair mechanisms involved in error-prone DNA repair. This quiz covers essential concepts related to environmental agents and their impact on DNA structures, including thymine dimers and base changes.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser