DNA Supercoiling Quiz
18 Questions
1 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

Which of the following is NOT a structural form of DNA?

  • A-DNA
  • B-DNA
  • Z-DNA
  • C-DNA (correct)

    • What is the approximate distance between stacked bases in the B form of DNA?

  • 34 nm
  • 3.4 nm
  • 0.34 nm (correct)
  • 340 nm

    • What is the number of hydrogen bonds in complementary base pairings in DNA?

  • 4
  • 1
  • 2 (correct)
  • 3

    • Which process can generate positive supercoils that must be relaxed for proper chromosome segregation?

    <p>Mitosis and Meiosis</p> Signup and view all the answers

    Which of the following is NOT a target of antibiotics used to treat bacterial infections?

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

    What stabilizes the double helix of DNA vertically?

    <p>Base stacking interactions</p> Signup and view all the answers

    What is the temperature at the midpoint of the transition during DNA denaturation?

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

    Which type of supercoil is generated when the DNA strands are separated at specific sites in a circular chromosome during processes such as DNA replication and transcription?

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

    Which type of topoisomerase cleaves both DNA strands, passes intact DNA through the gap, and reseals both DNA strands?

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

    What is the functional significance of negative supercoiling in genomic DNA?

    <p>Compaction of DNA with reduced torsional stress</p> Signup and view all the answers

    What is the role of RNA polymerases in DNA transcription?

    <p>Unwind DNA to form a negative supercoil</p> Signup and view all the answers

    Chargaff's rule states that the content of A is equal to the content of T, and the content of G is equal to the content of C. How can this rule be used to infer the base composition of a given molecule of DNA?

    <p>By analyzing the sequence of nucleotides in the molecule</p> Signup and view all the answers

    What is the relationship between Linking Number (Lk) and positive versus negative supercoiling?

    <p>Positive supercoiling increases Lk, while negative supercoiling decreases Lk</p> Signup and view all the answers

    What are the effects of Type I and Type II Topoisomerases on Linking Number (Lk)?

    <p>Type I Topoisomerases decrease Lk, while Type II Topoisomerases increase Lk</p> Signup and view all the answers

    What is the functional significance of DNA supercoiling and what is the role of Type I and Type II Topoisomerases?

    <p>DNA supercoiling helps stabilize the DNA double helix, and Type I Topoisomerases relieve positive supercoiling while Type II Topoisomerases relieve negative supercoiling</p> Signup and view all the answers

    Which of the following is NOT a physical property of DNA?

    <p>Increased absorbance of UV light</p> Signup and view all the answers

    What is the function of gyrase inhibitors in medicine?

    <p>To treat Bacillus anthracis infections</p> Signup and view all the answers

    What is the role of denaturation and reannealing in research and clinical medicine?

    <p>To detect sequences in fragments on Southern blots</p> Signup and view all the answers

    Study Notes

    DNA Structure and Function

    • The B form of DNA has an approximate distance of 0.34 nm between stacked bases.
    • Complementary base pairings in DNA have three hydrogen bonds in GC pairs and two hydrogen bonds in AT pairs.

    Topoisomerases and Supercoiling

    • Positive supercoils can be generated by process such as DNA replication and transcription, and must be relaxed for proper chromosome segregation.
    • Type II topoisomerases can generate negative supercoils by cleaving both DNA strands, passing intact DNA through the gap, and resealing both DNA strands.
    • Negative supercoiling in genomic DNA facilitates DNA replication, transcription, and recombination by reducing the number of positive supercoils.
    • Type I topoisomerases relax positive supercoils, while Type II topoisomerases relax both positive and negative supercoils.

    DNA Denaturation and Renaturation

    • DNA denaturation occurs at a temperature around 50-60°C, which is the midpoint of the transition.
    • Denaturation and reannealing are used in research and clinical medicine to identify specific DNA sequences, detect genetic mutations, and study gene expression.

    Antibiotics and DNA

    • Gyrase inhibitors are antibiotics that target bacterial DNA gyrase, preventing supercoiling and ultimately leading to cell death.
    • RNA polymerases are not a target of antibiotics used to treat bacterial infections.

    DNA Properties and Rules

    • Chargaff's rule states that the content of A is equal to the content of T, and the content of G is equal to the content of C, which can be used to infer the base composition of a given molecule of DNA.
    • Linking Number (Lk) is related to the degree of supercoiling, with positive supercoiling increasing Lk and negative supercoiling decreasing Lk.
    • Type I topoisomerases do not change Lk, while Type II topoisomerases change Lk.

    Important Clarifications

    • DNA is not a structural form of DNA.
    • Electrophoretic mobility is not a physical property of DNA.

    Studying That Suits You

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

    Quiz Team

    Related Documents

    Nucleic Acids I: DNA PDF

    Description

    Test your knowledge on DNA supercoiling and its role in processes such as replication and transcription. This quiz will cover topics such as positive and negative supercoils, strand separation, and the importance of DNA supercoiling in chromosomes.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser