LESSON 1: Introduction to Genetics

• genetics - field of biology that involves the study of genes, heredity, and variation in living organisms

  • deals with the molecular structure and function of genes, gene behavior in context of a cell or organism, patterns of inheritance from parent to offspring, and gene distribution, variation, and change in populations
• Gregor Mendel (1822-1884) - Father of Modern Genetics

  • his experiments on pea plants (Pisum sativum) conducted between 1856-1863 established many rules of the heredity, known as Mendelian Laws of Inheritance
• Charles Darwin (1809-1882) - established that all species of life have descended over time from a common ancestry

  • On the Origin of Species (1859) - scientific theory of evolution by natural selection
  • Natural Selection - organisms better suited for adaption to their environment survive, while those that are poorly suited to their environment do not (survival of the fittest)
• William Bateson (1861-1926) - a British biologist who applied Gregor Mendel's work to Charles Darwin's theory of evolution

  • Coined the term "genetics" from Greek genesis meaning "origin" in 1905
  • Popularized the use of the word genetics to describe the study of inheritance in his inaugural address to the 3rd International Conference on Plant Hybridization in London, England in 1906
• Hugo De Vries (1848-1935), Carl Correns (1864-1933), and Erich Von Tschermak-Seysenegg (1871-1962) - European botanists who rediscovered Mendel's laws in 1900

  • working independently on different plant hybrids and came to the same conclusions on inheritance as Mendel's
• Thomas Hunt (1866-1945) - established the chromosomal theory of inheritance

  • used fruit flies (Drosophila melanogaster) eye color mutations to demonstrate sex-linked inheritance inheritance patterns
  • concluded that the eye color gene must be located on the X chromosome
  • Nobel Prize winner for Physiology or Medicine in 1933 for his discoveries on the role of chromosomes on heredity
• Rosalind Franklin (1920-1958) - contributions to the discovery of the molecular structure of deoxyribonucleic acid (DNA), a constituent of chromosomes that serves to encode genetic information

  • chemist whose x-ray diffraction studies provided crucial clues to the structure of DNA
• James Watson (1928-Present) - in 1953, together with Francis Crick, he determined the structure of DNA in the X-ray crystallography "photo 51" of Rosalind Franklin and indicated that DNA had a helical structure

  • alongside Maurice Wilkins, he was awarded 1926 Nobel Prize in Physiology or Medicine for their discoveries on the molecular structure of nucleic acids and its significance for information transfer
• branches of genetics

  1. cytogenesis
  2. molecular genesis
  3. behavioral genetics
  4. population genetics
  5. classical genetics
• cytogenesis - deals with the study of physical basis of heredity

  • formation and development of cells
• molecular genesis - deals with the chemical basis of heredity

  • genomics - study of genes
  • proteomics - study of proteins
• behavioral genetics - study that deals with the role of genetic and environmental effects on behavior
• population genetics - study of the distribution and frequency of alleles within populations

  • transmission of traits in a large group of individuals through time
• classical genetics - oldest discipline of genetics covering the basic mechanisms on heredity discovered by Gregor Mendel

  • based on the cell division of chromosomes
• methods of genetics

  1. pedigree analysis
  2. karyotyping
  3. planned experimental breeding
  4. twin studies
  5. statistical analysis
• pedigree analysis - makes use of symbols as representation of the members of the family
• karyotyping - used to detect chromosomal abnormality

  • makes use of karyotype or karyogram (from Greek karyon meaning "kernel," "seed," or "nucleus" and typos for "general form" to represent the chromosomes
• planned experimental breeding hypothesis

  • null hypothesis - stated in a negative manner; of no significant difference
  • alternative hypothesis - stated in a positive manner
• identical or monozygotic twins - developed from one fertilized egg (ovum) that producing two babies with exactly the same genetic information

  • generally have the same sex, eye and hair color, as well as blood type
  • exact mirror face
• fraternal or dizygotic twins - developed from 2 different egg cells fertilized by 2 different sperm cells producing two genetically unique children

  • have different physical characteristics and features because they do not share similar chromosomes
  • can be different or same gender
• factors that increase the odds of having twins

  1. advancing age of the mother
  2. number of previous pregnancies
  3. heredity
  4. race
  5. assisted reproductive technique
• statistical analysis

  • chi square - commonly used for testing relationships between categorical variables
  • standard deviation - tells how far a set of numbers lie apart
  • mean - average that is used to derive the central tendency of the data in question
• application of genetics

  1. plant and animal improvement
  2. medicine
  3. genetic engineering
  4. legal application/forensic
  5. genetic counseling