CYTOGEN

• Genes


  Unit of heredity, segment of DNA carrying information
• History of Genetics

  1. Old Ideas

  2. Mid 1800’s Discoveries
• Categories of Traits

  • Morphological
  • Physiological
  • Behavioral
• More 20th Century Events
• Variation


  Simply differences in genetic sequence
• Major Events in the 20th Century
• Classical Genetics

  1. Based on Gregor Mendel’s 1st and 2nd laws

  2. Law of Segregation

  3. Law of Independent Assortment

  4. Based on the Chromosomal Theory of Inheritance
• Examples of genetic variation (within species)

  • Domesticated species
  • Human genetics
  • Natural Populations
• Genetics


  The study of heredity and variation
• Heredity


  Study of transmission of traits and biological information between generations
• Three (3) Primary Sources of Genetic Variation

  • Mutations
  • Gene flow
  • Sex
• Types of RNA

  • mRNA
  • tRNA - Transfer RNA
  • rRNA - Ribosomal RNA
• Nitrogenous Bases

  • Adenine
  • Guanine
  • Cytosine
  • Thymine
  • Uracil
• Evolutionary Genetics

  1. Based on the theory of Charles Darwin: Natural Selection

  2. Study about the changes in gene frequencies
• Molecular Genetics


  Based on the Central Dogma of Molecular Biology from DNA Replication to DNA Transcription to DNA Translation
• Table 1.1 - The Three Major Areas of Genetics - Classical, Molecular, and Evolutionary- and the Topics they cover

  • Classical Genetics
  • Molecular Genetics
  • Evolutionary Genetics
• History of Genetics

  1. Why Study History

  2. Old Ideas
• Despite knowing about inheritance in general, a number of incorrect ideas had to be generated and overcome before modern genetics could arise
• All life comes from other life. Living organisms are not spontaneously generated from non-living material
• All life comes from other life. Living organisms are not spontaneously generated from non-living material. This is in contrast with abiogenesis where living organisms may come from non-living material
• Preformation


  The theory that organisms develop from mini versions of themselves. People believe that the form of living things already exists higher than development
• Charles Darwin published The Origin of Species in 1859, which describes the theory of evolution by natural selection. This theory requires heredity to work
• Organisms develop

  By expressing information carried in their hereditary material. This is opposed to "preformation", the idea that in each sperm (or egg), is a tiny, fully-formed human that merely grows in size
• Species concept: offspring arises only when two members of the same species mate but with exceptions. Monstrous hybrids don’t exist
• Robert Hooke studied cork and coined the term "cell". Anton Van Leeuwenhook discovered living organisms particularly the protozoa and bacteria from rainwater
• The environment


  Can't alter the hereditary material in a directed fashion. There is no "inheritance of acquired characteristics". Mutations are random events
• Male and female parents contribute equally to the offspring. Ancient Greek idea: male plants a "seed" in the female "garden". Alleged New Guinea belief: sex is not related to reproduction
• Development of modern genetics

  Major events in mid-1800’s led directly to the development of modern genetics
• Friedrich Miescher isolated "nucleic acid" from pus cells in 1869. He was the first to identify DNA as a distinct molecule and that the genetic material is located in the nucleus
• Gregor Mendel published Experiments in Plant Hybridization in 1866, which lays out the basic theory of genetics leading to the discovery of chromosomes and their behavior. It was widely ignored until 1900 and he studied pea plants
• Major events in the 20th century led to the flourishing of modern genetics
• Walter Sutton hypothesized that the behavior of chromosomes during meiosis, leading to the discovery that genes are located on chromosomes
• Archibald Garrod discovered that alkaptonuria, a human disease, has a genetic basis
• Ernst Haeckel's experiments proved that the genetic material is indeed located in the nucleus
• Wilhelm Johannsen coined the term "gene"
• William Bateson discovered linkage between genes and coined the term "epistasis" which describes the interaction between two different traits where a certain gene masks the expression of another gene
• Epistasis


  The term coined to describe the interaction between two different traits
• Thomas Hunt Morgan discovered XX and XY chromosomes
• Thomas Hunt Morgan proved that genes are located on the chromosomes using Drosophila, a fruit fly
• Oswald Avery, Colin MacLeod, and Maclyn Mccarty showed that DNA can transform bacteria, demonstrating that DNA is the hereditary material in 1944