DNA Replication Quiz
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Questions and Answers

What enzyme is responsible for synthesizing mRNA during transcription?

  • DNA helicase
  • RNA polymerase (correct)
  • RNA exonuclease
  • RNA ligase

    • What is a codon?

  • A protein complex
  • A sequence of three nucleotides on mRNA (correct)
  • A sequence of amino acids
  • A three-nucleotide sequence on tRNA

    • Where does translation occur?

  • In the nucleus
  • In the endoplasmic reticulum
  • In the mitochondria
  • In the cytoplasm, at the ribosome (correct)

    • What is the first step of DNA replication?

    <p>Unwinding and unzipping DNA (C)</p> Signup and view all the answers

    What signals the end of translation?

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

    Which enzyme is responsible for adding nucleotides during DNA replication?

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

    What molecule carries amino acids to the ribosome?

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

    What is the central dogma of molecular biology?

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

    During transcription, which base pairs with adenine in RNA?

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

    What is a missense mutation?

    <p>A mutation that changes one amino acid in a protein (C)</p> Signup and view all the answers

    What occurs during the initiation step of translation?

    <p>Ribosome attaches to the start codon (D)</p> Signup and view all the answers

    What is the role of DNA ligase during DNA replication?

    <p>Seals gaps in the sugar-phosphate backbone (C)</p> Signup and view all the answers

    What happens to mRNA after transcription?

    <p>It exits the nucleus to the ribosome (D)</p> Signup and view all the answers

    Which of the following occurs during the elongation phase of translation?

    <p>Amino acids are joined by peptide bonds (B)</p> Signup and view all the answers

    What is the end result of DNA replication?

    <p>Two identical DNA molecules, each with one old and one new strand (A)</p> Signup and view all the answers

    Where does transcription occur within the cell?

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

    What is the main function of tRNA in protein synthesis?

    <p>Transfers amino acids to ribosomes (C)</p> Signup and view all the answers

    Which mutation type introduces a stop codon, terminating the protein early?

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

    What is the role of RNA Polymerase during transcription?

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

    What are the complementary base pairing rules in DNA?

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

    What occurs during the S phase of the cell cycle?

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

    In DNA replication, what is formed when helicase unwinds the DNA?

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

    Why is the lagging strand synthesized in fragments?

    <p>DNA polymerase can only add nucleotides in the 5’ to 3’ direction (D)</p> Signup and view all the answers

    What is the role of rRNA in protein synthesis?

    <p>Forms part of the ribosome structure and catalyzes synthesis (C)</p> Signup and view all the answers

    Study Notes

    DNA Replication

    • DNA replication ensures each new cell receives an exact copy of the DNA
    • It occurs during the S phase of the cell cycle, entirely within the nucleus
    • Steps of DNA Replication:
      • Unwinding and Unzipping DNA: Helicase breaks hydrogen bonds between nitrogenous bases, creating a replication fork. The two DNA strands are now exposed for complementary base pairing.
      • Complementary Base Pairing: Free nucleotides in the nucleus pair with the exposed bases on each DNA strand. Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G).
      • Joining of the New Strand: DNA polymerase synthesizes the new DNA strand by forming covalent bonds between the sugar-phosphate backbones. DNA ligase seals gaps in the sugar-phosphate backbone.
      • Result: Two identical DNA molecules, each with one original (parent) strand and one new strand (semi-conservative replication).
    • Key Enzymes in Replication:
      • Helicase: Unwinds and unzips DNA
      • DNA Polymerase: Adds nucleotides to form the new strand
      • DNA Ligase: Joins fragments of the DNA backbone

    Protein Synthesis

    • Protein synthesis converts genetic information from DNA into functional proteins. It consists of transcription and translation.

    • Transcription (DNA → mRNA):

      • Occurs in the nucleus and produces a single-stranded RNA molecule (mRNA) based on the DNA template
      • Steps of Transcription:
        • Unzipping the DNA: Helicase unwinds the DNA double helix
        • RNA Complementary Base Pairing: Free RNA nucleotides pair with the exposed DNA strand. Adenine (A) pairs with Uracil (U) in RNA (instead of Thymine). Cytosine (C) pairs with Guanine (G)
        • mRNA Synthesis: RNA polymerase links the RNA nucleotides, forming the mRNA strand. The mRNA strand detaches and exits the nucleus to the cytoplasm.

    • Translation (mRNA → Protein):

      • Occurs in the cytoplasm on ribosomes. Translation converts mRNA into a chain of amino acids (protein)
      • Steps of Translation:
        • Initiation: Ribosome attaches to the start codon (AUG) on mRNA. A tRNA with the complementary anticodon (UAC) brings the amino acid methionine.
        • Elongation: Ribosome reads mRNA codons. tRNA and amino acids are added to the growing polypeptide chain
        • Termination: Ribosome reaches a stop codon (UAA, UAG, or UGA). The polypeptide chain is released, folding into a functional protein.

    • Key Molecules in Protein Synthesis:

      • DNA: The template for genetic information.
      • mRNA: Carries genetic instructions from DNA to ribosomes.
      • tRNA: Transfers amino acids to ribosomes.
      • rRNA: A component of ribosomes that catalyzes protein synthesis.

    • Key Concepts and Terms:

      • Nitrogenous Bases
      • DNA: Adenine (A), Thymine (T), Cytosine (C), Guanine (G).
      • RNA: Adenine (A), Uracil (U), Cytosine (C), Guanine (G).
      • Genetic Code
      • Codons: Groups of three mRNA bases
      • Each codon specifies one amino acid
      • Mutations:
        • Point Mutation: A single base change
        • Silent Mutation: No effect on protein
        • Missense Mutation: Changes one amino acid
        • Nonsense Mutation: Introduces a stop codon, terminating the protein early
        • Frameshift Mutation: Insertion or deletion of bases, altering the reading frame

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    Related Documents

    Key Processes in DNA and Protein Synthesis PDF

    Description

    Test your knowledge on DNA replication processes and key enzymes. This quiz covers the steps involved, from unwinding DNA to the joining of new strands. Understand the importance of semi-conservative replication in cell division.

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