Biology Chapter: Molecular Genetics Quiz
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Questions and Answers

Which of the following is NOT a component of a nucleotide?

  • Pentose sugar
  • Phosphate group
  • Nitrogenous base
  • Fatty acid (correct)

    • What is the primary function of DNA?

  • Storing genetic information (correct)
  • Transporting amino acids to ribosomes
  • Catalyzing protein synthesis
  • Regulating gene expression

    • Which type of RNA carries genetic instructions from DNA to ribosomes?

  • tRNA
  • rRNA
  • mRNA (correct)
  • miRNA

    • Which of the following base pairs is NOT found in DNA?

    <p>Guanine (G) - Adenine (A) (C)</p> Signup and view all the answers

    Which type of RNA is responsible for the structural and catalytic components of ribosomes?

    <p>rRNA (D)</p> Signup and view all the answers

    Which type of RNA regulates gene expression by binding to mRNA?

    <p>miRNA and siRNA (B)</p> Signup and view all the answers

    What is the central dogma of molecular biology?

    <p>The flow of genetic information from DNA to RNA to protein (A)</p> Signup and view all the answers

    Which of the following best describes the structure of DNA?

    <p>Double-stranded helix (A)</p> Signup and view all the answers

    Which of the following is NOT a difference between DNA and RNA?

    <p>DNA uses ribose sugar, while RNA uses deoxyribose sugar. (B)</p> Signup and view all the answers

    Which process involves the synthesis of mRNA from a DNA template?

    <p>Transcription (C)</p> Signup and view all the answers

    What is the role of ribosomes in protein synthesis?

    <p>To assemble amino acids into polypeptide chains. (D)</p> Signup and view all the answers

    Which of the following is a pyrimidine base found ONLY in DNA?

    <p>Thymine (A)</p> Signup and view all the answers

    Which of the following accurately describes the flow of genetic information in a cell?

    <p>DNA → RNA → Protein (B)</p> Signup and view all the answers

    Why is DNA considered more stable than RNA?

    <p>DNA uses deoxyribose sugar instead of ribose sugar. (A)</p> Signup and view all the answers

    What is the name of the bond that connects a nitrogenous base to a pentose sugar in a nucleoside?

    <p>Beta-N-glycosidic bond (C)</p> Signup and view all the answers

    What is the primary site of DNA replication in a eukaryotic cell?

    <p>Nucleus (B)</p> Signup and view all the answers

    Which of the following is NOT a function of nucleic acids?

    <p>Transport of oxygen (C)</p> Signup and view all the answers

    Which of the following nucleotide triphosphates is primarily involved in cellular energy transfer?

    <p>ATP (C)</p> Signup and view all the answers

    Which of the following pairs of scientists proposed the double-helix structure of DNA?

    <p>James Watson and Francis Crick (C)</p> Signup and view all the answers

    What is the difference between ribose and deoxyribose?

    <p>Ribose has a hydroxyl group at the 2' carbon, while deoxyribose has a hydrogen atom at the 2' carbon. (C)</p> Signup and view all the answers

    What type of bond connects the sugar-phosphate backbone of DNA?

    <p>Phosphodiester bonds (A)</p> Signup and view all the answers

    Which of the following terms describes a nucleoside that has been esterified to a phosphate group?

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

    Which of the following is a purine nucleoside?

    <p>Guanosine (D)</p> Signup and view all the answers

    Which of the following is NOT a component of the Watson-Crick model of DNA structure?

    <p>Phospholipid bilayer (A)</p> Signup and view all the answers

    What is the significance of the major and minor grooves in DNA?

    <p>They provide sites for DNA binding proteins (A)</p> Signup and view all the answers

    What is the role of DNA in protein synthesis?

    <p>DNA serves as a template for the synthesis of RNA, which then directs protein synthesis. (C)</p> Signup and view all the answers

    Which of the following is a pyrimidine base?

    <p>Cytosine (C)</p> Signup and view all the answers

    Which of the following base pairings is NOT correct according to Chargaff's rule?

    <p>Thymine with Cytosine (B), Adenine with Guanine (C)</p> Signup and view all the answers

    What is the function of ribozymes?

    <p>To catalyze biochemical reactions (A)</p> Signup and view all the answers

    How many base pairs are present in one turn of the DNA helix?

    <p>10 (A)</p> Signup and view all the answers

    What is the type of bond that connects the nitrogenous bases in a DNA molecule?

    <p>Hydrogen bonds (B)</p> Signup and view all the answers

    Study Notes

    Nucleic Acids: Overview, Composition, and Functions

    • Nucleic acids are essential biomolecules forming the genetic blueprint for all living organisms
    • They are long polymers made of repeating nucleotides
    • Each nucleotide consists of three key components: a nitrogenous base, a pentose sugar, and a phosphate group

    Classification of Nucleic Acids

    • Deoxyribonucleic Acid (DNA): The primary genetic material in most organisms
      • Found in the nucleus, mitochondria, and chloroplasts
      • Double-stranded helix with complementary base pairing (adenine with thymine, guanine with cytosine)
      • Stores genetic information, provides a template for RNA synthesis, and facilitates replication
    • Ribonucleic Acid (RNA): Involved in protein synthesis and gene regulation
      • Single-stranded, contains uracil (U) instead of thymine (T)
      • Classified into different types based on function:
        • Messenger RNA (mRNA) (approximately 1-5% of total RNA): Carries genetic instructions from DNA to ribosomes for protein synthesis
        • Transfer RNA (tRNA) (approximately 10-15% of total RNA): Transports specific amino acids to the ribosome during translation
        • Ribosomal RNA (rRNA) (approximately 80-90% of total RNA): Forms the structural and catalytic components of ribosomes responsible for protein synthesis
        • Regulatory RNAs (miRNA and siRNA) (approximately 1-2% of total RNA): Regulates gene expression by binding to mRNA to inhibit translation or promote degradation

    The Central Dogma of Molecular Biology

    • Outlines the flow of genetic information in a biological system
    • The flow follows a one-way path: DNA → RNA → Protein

    DNA Replication

    • The process by which a cell copies its DNA before cell division
    • Ensures that daughter cells inherit identical genetic material

    Transcription

    • The process by which a segment of DNA is copied into RNA, specifically mRNA

    Translation

    • The process by which mRNA is translated into proteins at the ribosome
    • Where amino acids are assembled according to the mRNA sequence

    Differences Between DNA and RNA

    Feature DNA RNA
    Sugar Deoxyribose (lacks -OH at 2' carbon) Ribose (has -OH at 2' carbon)
    Nitrogenous Bases Contains thymine (T) Contains uracil (U) instead of thymine (T)
    Strand Structure Double-stranded (double helix) Single-stranded
    Molecular Stability More stable in alkaline conditions Less stable, prone to hydrolysis
    Function Stores genetic information Involved in protein synthesis and regulation
    Length Longer, millions of nucleotides Shorter, varies with type and function

    Composition of Nucleic Acids

    • Nucleic acids are complex macromolecules composed of nucleotides
      1. Nitrogenous Bases: These are organic molecules with nitrogen atoms;
      • Purines (larger, double-ring structures): Adenine (A), Guanine (G)
      • Pyrimidines (smaller, single-ring structures): Cytosine (C), Thymine (T), Uracil (U)
      1. Pentose Sugar:
      • Deoxyribose: Found in DNA (lacks hydroxyl group at the 2′ carbon)
      • Ribose: Found in RNA (has a hydroxyl group at the 2′ carbon)
      1. Phosphate Group: Contributes to the acidic nature and negative charge of nucleic acids and forms the sugar phosphate backbone through phosphodiester bonds between the 5' and 3' carbons

    Nucleosides

    • Formed when a nitrogenous base is attached to a pentose sugar via a beta-N-glycosidic bond

    Nucleotides

    • Formed when a nucleoside is esterified to a phosphate group

    Functions of Nucleic Acids

    • Genetic Information Storage: DNA serves as the repository of genetic instructions
    • Replication: DNA replicates itself to ensure accurate inheritance during cell division
    • Transcription and Translation: DNA directs RNA synthesis which subsequently instructs protein synthesis.
    • Energy Transfer: Nucleotides like ATP and GTP are essential for cellular energy transfer
    • Role in Coenzymes: Nucleic acids participate in redox reactions, metabolism, and energy production by forming part of coenzymes
    • Cell Signaling: Nucleic acids like cAMP act as second messengers in cell signaling
    • Catalysis (Ribozymes): Certain RNA molecules (ribozymes) act as enzymes, catalyzing biochemical reactions.

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    Description

    Test your knowledge on molecular genetics with this quiz that covers essential concepts such as DNA and RNA structure, functions, and the central dogma of molecular biology. Questions include identifying nucleotide components, RNA functions, and the significance of ribosomes in protein synthesis. Perfect for students studying genetics or molecular biology.

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