DNA Replication and Repair Mechanisms
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Questions and Answers

Which enzyme is most likely to be mutated if the joining together of Okazaki fragments is impaired?

DNA ligase

Which of the following does cytosine pair with?

  • Thymine
  • Guanine (correct)
  • A pyrimidine
  • Adenine
  • Prokaryotes contain a ________ chromosome, and eukaryotes contain ________ chromosomes.

  • Single-stranded circular; single-stranded linear
  • Double-stranded linear; double-stranded circular
  • Double-stranded circular; double-stranded linear (correct)
  • Single-stranded linear; single-stranded circular
  • DNA replicates by which of the following models?

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

    The initial mechanism for repairing nucleotide errors in DNA is ________.

    <p>DNA polymerase proofreading</p> Signup and view all the answers

    A promoter is ________.

    <p>A specific sequence of DNA nucleotides</p> Signup and view all the answers

    Portions of eukaryotic mRNA sequence that are removed during RNA processing are ________.

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

    The RNA components of ribosomes are synthesized in the ________.

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

    How long would the peptide be that is translated from this mRNA sequence: 5'-AUGGGCUACCGA-3'?

    <p>4</p> Signup and view all the answers

    Control of gene expression in eukaryotic cells occurs at which level(s)?

    <p>Epigenetic, transcriptional, post-transcriptional, translational, and post-translational levels</p> Signup and view all the answers

    Post-translational control refers to:

    <p>Regulation of gene expression after translation</p> Signup and view all the answers

    Describe the organization of the eukaryotic chromosome.

    <p>Eukaryotic chromosomes consist of a DNA-protein complex that is organized in a compact manner which permits the large amount of DNA to be stored in the nucleus of the cell.</p> Signup and view all the answers

    Describe the structure and complementary base pairing of DNA.

    <p>The structure of DNA is a double helix structure and one side of DNA is complementary to the other, which means that one side can be rebuilt if destroyed because specific nucleotides bond to one another.</p> Signup and view all the answers

    How do the linear chromosomes in eukaryotes ensure that their ends are replicated completely?

    <p>Telomerase has an inbuilt RNA template that extends the 3′ end, so a primer is synthesized and extended. Thus, the ends are protected.</p> Signup and view all the answers

    Transcribe and translate the following DNA sequence (nontemplate strand): 5'-ATGGCCGGTTATTAAGCA-3'

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

    Describe how controlling gene expression will alter the overall protein levels in the cell.

    <p>Controlling gene expression would change how many proteins are produced because when certain genes are expressed, a certain protein is created.</p> Signup and view all the answers

    Study Notes

    DNA Replication and Repair Mechanisms

    • DNA ligase is crucial for joining Okazaki fragments during DNA replication; a mutation in this enzyme would impair the replication process.
    • Cytosine pairs specifically with guanine through hydrogen bonding, maintaining the integrity of the DNA structure.
    • Prokaryotic organisms possess a double-stranded circular chromosome, whereas eukaryotic organisms have double-stranded linear chromosomes.

    Models of DNA Replication

    • The semiconservative model is the accepted method of DNA replication, where each new DNA helix contains one original strand and one newly synthesized strand.

    Error Repair and Gene Regulation

    • DNA polymerase proofreading serves as the primary mechanism for correcting nucleotide errors during DNA replication.
    • A promoter is defined as a specific sequence of DNA nucleotides that initiates transcription of a gene.

    RNA Processing and Ribosome Synthesis

    • Introns are non-coding segments of eukaryotic mRNA that are removed during RNA processing, while exons are retained and expressed.
    • In prokaryotic cells, RNA components of ribosomes are synthesized in the cytoplasm; in eukaryotic cells, they are synthesized in the nucleolus.

    Translation and Peptide Formation

    • The mRNA sequence 5'-AUGGGCUACCGA-3' translates to a peptide of four amino acids, demonstrating the codon-to-amino acid translation process.

    Gene Expression Control

    • Gene expression in eukaryotic cells can be controlled at multiple levels: epigenetic, transcriptional, post-transcriptional, translational, and post-translational.
    • Post-translational control refers to the regulation of gene expression following the translation of mRNA into protein.

    Eukaryotic Chromosome Structure

    • Eukaryotic chromosomes are organized as a DNA-protein complex, allowing for compact storage of genetic material within the nucleus.

    DNA Structure and Base Pairing

    • DNA is structured as a double helix; each strand is complementary, allowing for accurate replication and repair.

    Telomere Replication

    • Telomerase extends the 3′ ends of linear chromosomes using an RNA template, ensuring that chromosome ends are fully replicated and protected.

    Transcription and Translation of DNA

    • The transcription of the non-template DNA strand results in a complementary RNA sequence, highlighting the base-pairing rules between DNA and RNA.

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    Description

    This quiz covers key concepts in DNA replication and repair mechanisms. Explore the roles of enzymes like DNA ligase and DNA polymerase, understand the models of DNA replication, and learn about RNA processing. Test your knowledge on how genetic information is accurately copied and maintained.

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