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Induced Mutations quiz #1

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  • What are examples of induced mutations?
    Examples of induced mutations include those caused by base analogs, alkylating agents, intercalating agents, UV light (causing thymine dimers), and ionizing radiation (such as gamma rays creating free radicals). These mutations result from exposure to chemicals or radiation that alter DNA.
  • What is the primary difference between spontaneous and induced mutations?
    Induced mutations are caused by exposure to external agents like chemicals or radiation, while spontaneous mutations occur naturally without such exposure.
  • How do base analogs lead to mutations in DNA?
    Base analogs resemble normal DNA bases but do not pair correctly, causing incorrect base pairing and resulting in mutations when incorporated into DNA.
  • What effect do alkylating agents have on DNA bases?
    Alkylating agents add alkyl groups to DNA bases, altering their binding properties and often causing transition mutations.
  • Why can intercalating agents cause severe cell death?
    Intercalating agents distort the DNA helix, blocking replication and repair processes, which can lead to severe cell death.
  • What type of DNA damage is caused by UV light?
    UV light causes the formation of dimers between pyrimidine bases, disrupting normal base pairing and leading to mutations.
  • How does ionizing radiation such as gamma rays damage DNA?
    Ionizing radiation creates free radicals that can severely damage DNA by stealing electrons and protons from molecules.
  • What is the purpose of using rat liver extracts in the Ames test?
    Rat liver extracts are used to mimic human metabolism by breaking down chemicals before exposing them to bacteria, providing a more accurate assessment of mutagenic potential.
  • Why is it important to simulate digestion in mutagenicity testing?
    Simulating digestion is important because chemicals may become mutagenic only after being metabolized in the body, which is replicated using rat liver extracts.
  • What role do DNA polymerases play in the context of intercalating agent-induced mutations?
    DNA polymerases may be unable to replicate or transcribe DNA past the distortion caused by intercalating agents, resulting in blocked replication and potential mutations.
  • How does ultraviolet (UV) radiation damage DNA?
    Ultraviolet (UV) radiation damages DNA by causing the formation of dimers between pyrimidine bases, such as thymine, which disrupt normal base pairing and can lead to mutations.
  • What type of DNA damage is caused by ultraviolet (UV) radiation?
    Ultraviolet (UV) radiation causes DNA damage by inducing the formation of pyrimidine dimers, most commonly thymine dimers, which interfere with normal DNA replication and repair.
  • Describe the molecular effect of UV light on DNA structure.
    UV light induces the formation of covalent bonds between adjacent pyrimidine bases in DNA, creating dimers that distort the DNA helix and prevent proper base pairing.