IGCSE Biology 3 Views 1 Answers
State that ionising radiation and some chemicals increase the rate of mutation
State that ionising radiation and some chemicals increase the rate of mutation
Answer
Ionizing radiation and certain chemicals significantly increase the rate of mutation in organisms.
Ionizing Radiation
- Mechanism: Ionizing radiation, such as X-rays and gamma rays, causes direct damage to DNA by breaking the sugar-phosphate backbone or inducing the formation of reactive oxygen species (ROS) that can further damage DNA. This damage can lead to various types of mutations, including point mutations, insertions, deletions, and chromosomal rearrangements.
- Effects: Studies have shown that exposure to ionizing radiation can result in a higher frequency of mutations, particularly in germline cells, which can be passed on to subsequent generations. For example, research indicates that paternal exposure to ionizing radiation significantly increases the occurrence of de novo mutations in offspring.
Chemical Mutagens
- Types of Chemical Mutagens: Various chemicals can act as mutagens by directly altering DNA or by producing reactive intermediates that cause genetic changes. Common examples include:
- Alkylating Agents: Chemicals like ethyl nitrosourea and mustard gas add alkyl groups to DNA bases, leading to mispairing during replication.
- Deaminating Agents: Compounds such as nitrous acid can convert cytosine into uracil, resulting in point mutations when the DNA is replicated.
- Intercalating Agents: These chemicals insert themselves between DNA bases, disrupting the normal base-pairing and potentially causing frameshift mutations
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