DNA Structure and Function Quiz
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Questions and Answers

What defines the polarity of a DNA strand?

  • Presence of double bonds between bases
  • Chemical makeup of purines and pyrimidines
  • Number of base pairs along the strand
  • Arrangement of phosphate and sugar groups (correct)
  • Which base pairing occurs between the strands of DNA?

  • A-C and G-T
  • G-T and A-C
  • C-G and A-T (correct)
  • A-G and C-T
  • What structural feature of DNA allows for the specific recognition of base sequences by proteins?

  • Antiparallel orientation
  • The helical twist of DNA
  • Major and minor grooves (correct)
  • Presence of histones
  • In the context of DNA replication, what is the term used to describe the mechanism of copying DNA?

    <p>Semi-conservative replication</p> Signup and view all the answers

    Which of these is an exception to the central dogma of molecular biology?

    <p>Reverse transcription</p> Signup and view all the answers

    What is the primary reason for DNA's acidic nature?

    <p>Phosphate group</p> Signup and view all the answers

    What is the direction in which DNA and RNA sequences are conventionally written?

    <p>5' to 3'</p> Signup and view all the answers

    Where is DNA predominantly located within eukaryotic cells?

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

    Which end of a DNA strand contains the phosphate group?

    <p>5' end</p> Signup and view all the answers

    What type of bonding is primarily involved in the attachment of proteins to specific DNA sequences?

    <p>Hydrogen bonding</p> Signup and view all the answers

    What is the primary reason for the difference in chromosome number between somatic cells and gametes?

    <p>Meiosis results in haploid cells</p> Signup and view all the answers

    Which element is crucial for the attachment of the mitotic spindle during mitosis?

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

    Which of the following statements about heterochromatin is correct?

    <p>It can contain satellite DNA</p> Signup and view all the answers

    What is the role of chromatin remodeling complexes?

    <p>To allow access of DNA-binding enzymes to chromatin</p> Signup and view all the answers

    What happens to introns during RNA processing?

    <p>Introns are spliced out of the RNA</p> Signup and view all the answers

    Which of the following is NOT a feature of nucleosomes?

    <p>They directly initiate DNA replication</p> Signup and view all the answers

    How do histone tails contribute to gene regulation?

    <p>By mediating nucleosome interactions that compact chromatin</p> Signup and view all the answers

    Which term describes mobile genetic elements that replicate and insert themselves into various genomic locations?

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

    Which of the following correctly describes the structure of chromosomes during interphase?

    <p>They resemble spaghetti and are not condensed</p> Signup and view all the answers

    Epigenetic marks, such as DNA methylation, influence which of the following?

    <p>The activity status of specific genes</p> Signup and view all the answers

    Study Notes

    DNA Structure and Function

    • DNA is a double helix structure with two strands running antiparallel (5' to 3' and 3' to 5').
    • The strands are held together by hydrogen bonds between complementary base pairs (A-T and G-C).
    • DNA's structure allows it to be copied and used as a template for other molecules (central dogma).
    • The 5' end has a phosphate group, and the 3' end has a hydroxyl group. This polarity is important for DNA replication and function.
    • Base pairs form between strands due to hydrogen bonding.
    • A-T and G-C are the complementary base pairs.
    • DNA sequences are always written 5' to 3'.

    DNA Replication

    • DNA replication is semi-conservative, meaning each new DNA molecule consists of one original strand and one new strand.
    • Cells have mechanisms for copying DNA accurately.
    • DNA replication follows chemical properties of the existing DNA.

    Chromatin Structure

    • Chromatin is DNA bound to proteins (histones).
    • Nucleosomes are the basic units of chromatin structure.
    • Nucleosomes are made up of DNA wrapped around histone proteins.
    • Heterochromatin is tightly packed DNA, typically inactive.
    • Euchromatin is less tightly packed, allowing for transcription.
    • Histone tails are points of modification that affect chromatin structure.

    DNA & Proteins

    • Proteins bind to DNA, interacting with major and minor grooves in the double helix.
    • This binding allows sequences of DNA to be recognized by proteins that regulate gene expression.

    Human Genome

    • The human genome consists of 46 chromosomes (23 pairs).
    • All body cells contain the same DNA.
    • Chromosomes condense during mitosis.
    • Sperm and egg cells contain only half (23) the number of chromosomes.
    • Important regions include telomeres, centromeres, origin points, which are parts of a functional and stable chromosome.

    Transposons

    • Transposons are mobile genetic elements within the genome.
    • They multiply and insert themselves at different places on DNA (genome).

    Epigenetics

    • Histone modifications and DNA methylation alter chromatin structure, affecting gene activity without altering the underlying DNA sequence.
    • These changes, called epigenetic marks, control gene expression patterns.

    Chromosomes

    • Chromosomes, during interphase, are less condensed forms of DNA, known as euchromatin.
    • Chromosomes are highly condensed forms during mitosis, known as heterochromatin.
    • Chromosome structures have replication origins, centromeres and telomeres.

    Nucleus

    • Most DNA is contained within the cell nucleus.
    • Other locations for DNA include mitochondria.

    Mitochondrial DNA

    • Mitochondrial DNA is inherited maternally.

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    Description

    Test your knowledge on the intricate structure and function of DNA, including the properties of double helix and the importance of base pairing. Explore concepts related to DNA replication and chromatin structure in this comprehensive quiz. Perfect for students and enthusiasts of molecular biology.

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