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GOB Chemistry: DNA Mutations, Recombinant DNA, and PCR

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  • What is a mutation in DNA replication?
    A mutation is an error in the base sequence of DNA that is passed on during replication.
  • Define mutagen.
    A mutagen is a substance that causes mutations, such as viruses, chemicals, or ionizing radiation.
  • What is a point mutation?
    A point mutation is a substitution of one base for another in DNA, changing a codon in mRNA and possibly the amino acid in a protein.
  • What is a silent mutation?
    A silent mutation changes a base but results in the same amino acid, causing no effect on the organism.
  • What is a missense mutation?
    A missense mutation changes a base and results in a different amino acid, which may moderately affect the protein.
  • What is a nonsense mutation?
    A nonsense mutation changes a base to produce a stop codon, prematurely ending protein synthesis.
  • Describe a frameshift mutation.
    A frameshift mutation involves insertion or deletion of bases, altering the reading frame and changing all downstream amino acids.
  • What are recombinant DNA molecules?
    Recombinant DNA contains DNA segments from two or more sources combined artificially.
  • What are the three key elements needed to form recombinant DNA?
    1. A DNA molecule (usually a plasmid), 2. A restriction enzyme to cut DNA, 3. A gene from another organism to insert.
  • What is the role of EcoRI in recombinant DNA technology?
    EcoRI is a restriction enzyme that cuts DNA at specific sequences, creating sticky ends for gene insertion.
  • What are sticky ends in DNA?
    Sticky ends are unpaired bases at the ends of DNA fragments after cutting with restriction enzymes, allowing complementary base pairing.
  • How is a recombinant plasmid formed?
    A gene fragment and plasmid with complementary sticky ends are joined by DNA ligase, forming a recombinant plasmid.
  • What is the purpose of inserting recombinant plasmids into bacteria?
    Inserted plasmids allow bacteria to produce proteins encoded by the foreign gene, useful for producing human insulin and other proteins.
  • What is genomics?
    Genomics is the study of whole sets of genes and their functions in organisms.
  • Give an example of genetically modified crops.
    Bt corn contains a bacterial gene producing a toxin that kills pests like the European corn borer.
  • What is gene therapy?
    Gene therapy replaces a disease-causing gene with a healthy one to cure or prevent genetic diseases.
  • What is the polymerase chain reaction (PCR)?
    PCR is a technique that amplifies a specific DNA segment, producing millions of copies.
  • What are the four elements needed for PCR?
    1. DNA segment to copy, 2. Two primers, 3. DNA polymerase enzyme, 4. Nucleoside triphosphates (A, T, C, G).
  • What are the main steps of PCR?
    1. Heat to separate DNA strands, 2. Add primers, 3. DNA polymerase extends primers to copy DNA.
  • How is DNA fingerprinting performed?
    DNA is amplified by PCR, cut by restriction enzymes, and fragments separated by gel electrophoresis to create a unique pattern.
  • What is a virus?
    A virus is an infectious agent with DNA or RNA inside a protein coat that requires a host to replicate.
  • What is a retrovirus?
    A retrovirus has an RNA core and uses reverse transcription to make DNA from RNA inside a host cell.
  • What disease is caused by the retrovirus HIV?
    Acquired immune deficiency syndrome (AIDS) is caused by the human immunodeficiency virus (HIV).