Lecture Notes: Mutations

Introduction to Mutations

• Fascination with mutations often begins in childhood, influenced by media.
• Basic Definition: Mutations are changes in genetic material within nucleic acids (RNA and DNA).
• All living organisms and viruses, which contain RNA or DNA, can undergo mutations.
• Effects of Mutations:
  • Neutral: No significant effect on the organism.
  • Harmful or Helpful: Depending on the context and environment.
  • Mutations are random; organisms cannot will mutations.

Causes of Mutations

• External Factors: Chemicals, excessive radiation.
• Internal Factors: Errors during DNA replication in the interphase.
• Cells replicate DNA before division, leading to possible errors.

Types of Mutations

Gene Mutations

• Definition: Changes in one or more DNA bases that can affect protein synthesis and traits.
• Types:
  • Substitution: Wrong base matched.
  • Insertion: Extra base(s) added, leading to a frameshift.
  • Deletion: Base removed, also leading to a frameshift.
• Frameshift Mutations: Affect the reading of bases in threes, possibly altering amino acid sequences.

Chromosomal Mutations

• Chromosomes are highly organized DNA structures with many genes.
• Human chromosome number: 46 (23 from each parent).
• Fruit fly chromosome number: 8 (4 from each parent).
• Types:
  • Duplication: Extra copies of genes.
  • Deletion: Genetic material breaks off.
  • Inversion: Segment reverses and reattaches.
  • Translocation: Segment breaks off and attaches elsewhere.

Vulnerable Times for Mutations

• During DNA replication and meiosis.
• Meiosis: Can result in nondisjunction, leading to incorrect chromosome numbers in gametes.

Inheritance of Mutations

• Asexual reproduction: Daughter cells inherit mutations.
• Sexual reproduction: Mutations in sperm/egg cells can be passed to offspring.
• Example: Fruit flies are often used in mutational inheritance studies.

Human Genetic Disorders

• Sickle Cell Anemia:
  • Caused by a substitution gene mutation affecting hemoglobin.
  • Inheritance of two mutated genes leads to the disorder.
  • Carriers (one mutated gene) often have protection against malaria.
• Genetic disorders and mutations are a major research focus.
• Genetic counselors assist affected families.

Conclusion

• Importance of studying mutations and genetic disorders.
• Encouragement to explore careers related to genetics.
• Reminder to stay curious and continue learning.