MOD 1 Genetics LECTURE

• There is not much assertion on when genetics first started
• The people of ancient times first recognized the hereditary nature of traits when they started selectively breeding organisms, animals, and plants
• Ancient people had a hunch that parent organisms pass on genetic material or characteristics to their offspring
• Selective breeding


  Process used to develop organisms with desirable characteristics
• Domestication of dogs: the dogs evolved from the wolf family
• Cabbage, broccoli, cauliflower, Brussels sprouts, and kales - all derived from the same plant
• Broccoli


  Developed from wild cabbage that had suppressed flower development
• Kale


  Derived from wild cabbage plants that have larger leaves
• Hippocrates' view on humors


  • Bearers of hereditary traits
  • Passed on to the offspring
  • Could be healthy or diseased; diseased humors account for congenital diseases
  • Could be altered before passed onto offspring
• We can no longer accept Hippocrates' view on humors
• Aristotle's view on vital heat


  • Contained in male semen
  • Can produce offspring of the same form as the parent
  • Not enough alone to make an offspring, needs to be combined with menstrual blood produced by the female. It is the physical substance
• Considering the limited knowledge at the time, Aristotle's view was quite sound as he had an idea that there needs to be a contribution between the male and female parents
• The development of genetics was slow in the 1600-1850 interval
• Theory of Epigenesis


  Organism develops from the fertilized egg by a succession of developmental events that transform the egg into an adult
• The Theory of Epigenesis still holds true up until today, but it cannot entirely explain heredity
• Theory of Preformation


  Fertilized egg contains a complete miniature adult called a homunculus
• The Theory of Preformation is not true, the fertilized egg does not contain the actual miniature adult yet
• Cell Theory


  • All living organisms are composed of one or more cells
  • All cells arise from pre-existing cells
  • Cells are the fundamental structural unit of living organisms
• The discovery of the microscope by Antonie van Leeuwenhoek enabled studies on the structure of the cell, advancement of DNA, and what molecules are in the cell
• Charles Darwin's biological observation led him to believe that species are brought about by evolution or "descent with modification"
• Theory of Natural Selection

  • Population tends to contain more offspring than the environment can support, leading to competition or struggle for survival among individuals
  • Individuals with heritable traits that allow them to adapt to their environment are better able to survive and reproduce than those with less adaptive traits
  • The adapted trait becomes common in the population
• Darwin's Theory of Natural Selection lacked ideas regarding the transmission of traits
• Gregor Mendel sealed the gap in Darwin's theory by publishing a paper in 1866 showing how traits were passed from generation to generation in pea plants
• In 1900, it was brought to light that the pattern of transmission of traits in pea plants holds true for other organisms as well
• Mendel's work on pea plants became the general model of how traits are inherited: Mendelian Inheritance
• Advantageous traits

  Traits that are reproduced and represented in succeeding generations
• Darwin brought about the ideas of evolution and natural selection
• Darwin did not know how adaptive traits are transmitted from one generation to another
• Gregor Mendel


  Augustinian monk who in 1866 published a paper showing how traits were passed from generation to generation in pea plants
• In 1900 it was brought to light that the pattern of transmission of traits in pea plants holds true for other organisms as well
• Mendelian Inheritance


  The general model of how traits are inherited
• Mendel sealed the gap in Darwin's theory by postulating the general model of how traits are inherited
• Chromosomal Theory of Inheritance


  Heredity and development were dependent on genetic information residing in genes contained in chromosomes, which were then contributed to each individual by gametes
• Genes


  The basic units of heredity that get passed on from the parents to the offspring; sequence of DNA which encodes proteins
• Chromosomes


  Long stretch of genes; the number of chromosomes differs in each species
• Gametes


  Reproductive cells (sperm cell and egg cell) that contain the haploid chromosome number which combines during fertilization to become the genome of the offspring
• Mendel's work, the foundation of genetics, showed that traits are passed from parents to offspring in predictable ways
• Mendel deviated from descriptive or qualitative analysis which was commonly adopted at that time
• Genes and heredity behave in the same/predictable ways
• Chromosomal Theory of Inheritance

  Unites Mendel's factors that are contributed by parents to offspring and Meiosis, the cell reproduction where the resulting daughter cells only have half the whole complement