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AQA GCSE FOUNDATION Biology: Genetic Variation and Mutation

Date  |  Category Biology
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Genetic Variation and Mutation: The Foundation of Diversity and Evolution

What is Genetic Variation?

Genetic variation refers to the differences in DNA sequences among individuals within a population. These variations can be small, like a single nucleotide change, or large, like a whole gene duplication.

Why is Genetic Variation Important?

Sources of Genetic Variation

  1. Mutations: Changes in the DNA sequence. Mutations can be spontaneous or caused by environmental factors like radiation.
    • Types of Mutations:
      • Point mutations: Single nucleotide changes (e.g., A to G)
      • Insertions and deletions: Adding or removing nucleotides
      • Chromosomal mutations: Large-scale changes in chromosome structure
    • Effects of Mutations: Mutations can be:
      • Beneficial: Improve fitness
      • Harmful: Decrease fitness
      • Neutral: Have no effect on fitness
  2. Sexual Reproduction: The shuffling of genes during meiosis and fertilization creates new combinations of alleles. This increases genetic variation within offspring and contributes to population diversity.

How Mutations Drive Evolution

Example: Antibiotic Resistance in Bacteria

Bacteria can develop resistance to antibiotics through mutations. A mutation might occur in a gene that encodes a protein involved in antibiotic breakdown. If this mutation makes the protein more effective, the bacteria will be able to survive in the presence of the antibiotic and reproduce. Over time, the resistant strain will become dominant in the population.

Key Points to Remember

Further Exploration

By understanding the concepts of genetic variation and mutation, you can gain a deeper appreciation for the incredible diversity of life on Earth and the processes that drive evolution.