Overview
This lecture introduces genetics, covering its historical development, core concepts, major contributors, branches, and practical applications in fields like medicine, agriculture, and forensics.
Basics of Genetics
- Genes, inherited from parents, determine physical characteristics and biological identity.
- Some traits are dominant (expressed) while others are recessive (masked unless paired).
- Genetics studies how traits are passed between generations and how genes/DNA interact with the environment.
- The term "genetics" was coined by William Bateson in 1905.
History and Key Discoveries in Genetics
- Early theories included Lamarck's inheritance of acquired traits and Darwin’s Pangenesis (disproved).
- Gregor Mendel (1865) established the basic rules of inheritance with pea plant experiments.
- Friedrich Miescher (1869) isolated nucleic acids (nuclein), foundational for understanding DNA.
- Chromosomes as genetic carriers named by Waldeyer-Hartz (1888).
- Rediscovery of Mendel’s work (1900) marked the start of classical genetics.
- The chromosomal theory of inheritance was formalized by Sutton and Boveri (1902).
- Hardy-Weinberg Principle (1908) explains how allele frequencies remain constant absent evolutionary forces.
- Significant advances include identifying DNA as the hereditary material (Avery et al., 1944), discovering DNA structure (Watson & Crick, 1953), and genome sequencing technologies.
Notable Contributors and Milestones
- Key figures: Mendel, Miescher, Haeckel, Flemming, Morgan, Sturtevant, Franklin, Wilkins, Watson & Crick, Nirenberg, Mullis, Charpentier & Doudna.
- Nobel Prizes awarded for DNA structure, genetic code, PCR, genome editing, and mRNA vaccine development.
Branches of Genetics
- Classical Genetics: Inheritance patterns and Mendelian laws.
- Cytogenetics: Chromosomes, mitosis/meiosis, and abnormalities.
- Molecular Genetics: DNA structure, gene expression, editing, and engineering.
- Microbial Genetics: Gene function in microorganisms including conjugation and transformation.
- Human Genetics: Traits and diseases unique to humans.
- Medical Genetics: Genetic basis of diseases, diagnosis, treatment, and counseling.
- Population Genetics: Variation within and between populations; evolution.
Applications and Practice in Genetics
- Plant/Animal Breeding: Selective breeding for desired traits.
- Medicine: Genetic mapping, disease diagnosis, therapy, and counseling.
- Legal: DNA fingerprinting in forensics and paternity testing.
- Genetic Engineering: Production of insulin, vaccines, hormones, antibodies, and other drugs.
Key Terms & Definitions
- Gene — Fundamental unit of heredity, transmits traits from parents to offspring.
- Chromosome — DNA-containing structure carrying genetic information.
- Allele — Different forms of a gene at a specific locus.
- Genotype — Genetic makeup of an organism.
- Phenotype — Observable physical/physiological traits resulting from genotype and environment.
- Mitosis/Meiosis — Types of cell division; mitosis produces identical cells, meiosis produces gametes.
- Hardy-Weinberg Principle — States allele/genotype frequencies remain unchanged without evolutionary forces.
- Genetic Linkage — Genes located close together on a chromosome are inherited together.
Action Items / Next Steps
- Review key historical figures and their contributions to genetics.
- Study the definitions and processes of main branches of genetics.
- Practice interpreting gel electrophoresis images for forensics and paternity testing.
- Prepare for possible assignments on genetic terminology and historical milestones.