Lecture 1: Science of Heredity and Variation

• Genetics is the study of heredity and variation.
• Heredity is the transmission of traits from generation to generation through genes.
• Variation deals with genetic differences between organisms.
• Genetics was coined by William Bateson in 1905.
• Two important attributes of genes:

  • inherited from generation to generation in such fashion that each progeny has a physical copy of this material.
  • provides information regarding the structure, function, and other biological properties of the characteristic or trait it controls.
• Theory of Pangenesis by Aristotle - semen was formed everywhere in a man's body and such semen reflected the characteristics of the body part it was formed.
• Theory of Inheritance and Acquired Characteristics by Jean Baptiste de Lamarck - inheritance acquired characteristics was in turn proposed to be the fundamental mechanism of evolutionary change.
• Germplasm Theory by August Weismann

  • first challenged theory pf pangenesis
  • experiment on mice tail proposed that germplasm or sex cells perpetuated themselves in reproduction generation after generation.
• Chromosome Theory of Inheritance by T. Morgan and C. Bridges - discovery of sex chromosomes and by the demonstration of the association between specifc genes and specific chromosomes. Each chromosome contained many genes.
• Cytogenetics - branch that studies chromosome
• Molecular Genetics - studies the structure and function of genes at molecular level
• Developmental Genetics - how genes control growth and development of an organism throughout its life cycle.
• Quantitative Genetics- studies the role of genetics and environmental factors on the inheritance of traits.
• Population Genetics - fate of genes in the population and the factors that change the frequencies of genes and alleles in populations over space and time.
• Biochemical Genetics - relationship of genes and their control over function of an enzyme in metabolic pathway.
• Evolutionary Genetics - how genetic variation leads to speciation and adaptation and genetic change in response to selection within populations.
• Human Genetics - studies traits, diseases and abnormalities in humans that are inherited.
• Behavioral Genetics - studies how genetic and environmental influences would affect behavior.