Lecture Notes: Understanding Mutations

Introduction to Mutations

• Personal curiosity about mutations inspired by movies.
• Basic Definition: A mutation is a change in genetic material, specifically within nucleic acids such as RNA and DNA.
• All living organisms (animals, plants, fungi, protists, bacteria, Archaea) and viruses can have mutations.

Types of Mutations

Neutral Mutations

• Some mutations do not change the amino acid due to "silent mutations" where the codon still codes for the same amino acid.

Harmful and Helpful Mutations

• Mutations are random and cannot be "willed" by the organism.
• Example in Natural Selection: A bacterium may already possess a mutation that allows it to survive antibiotics.

External and Internal Mutation Factors

• External: Certain chemicals, excessive radiation.
• Internal: DNA replication errors during interphase.

Gene Mutations

• DNA changes can affect genes, which code for proteins and influence traits.
• Types of Gene Mutations:
  • Substitution: Wrong base matched.
  • Insertion: Extra base(s) added.
  • Deletion: Base removed.
  • Frameshift Mutation: Caused by insertions or deletions; affects the reading frame of codons.

Chromosomal Mutations

• Chromosomes are highly organized structures made of DNA and proteins.
• Human chromosomes: 46 total (23 from each parent).
• Types of Chromosomal Mutations:
  • Duplication: Extra copies of genes.
  • Deletion: Genetic material breaks off.
  • Inversion: Chromosome segment reversed.
  • Translocation: Fragment attaches to another chromosome.

Mutation Timing and Inheritance

• Vulnerable during DNA replication and meiosis.
• Meiosis: Creates sperm and egg cells with half the chromosomes, but nondisjunction can occur, leading to too many or too few chromosomes.
• Mutations can be inherited:
  • Asexually through division in protists.
  • Sexually if present in sperm or egg cells.

Case Study: Fruit Flies and Sickle Cell Anemia

• Fruit fly mutations are widely studied.
• Sickle Cell Anemia:
  • Caused by a substitution mutation in the hemoglobin gene.
  • Inheriting two copies (one from each parent) causes the disorder.
  • Carriers (one mutated gene) are asymptomatic but have some protection against malaria.
  • Improved treatment but no cure yet.

Importance of Studying Mutations

• Study of mutations and genetic disorders is a vital field.
• Genetic counselors assist families with genetic disorders.
• Encouragement to explore careers in genetics and mutations.

Conclusion: As emphasized by The Amoeba Sisters, stay curious and continue learning about the fascinating world of genetics and mutations.