SBI3U - Unit 3 Genetics (Lesson 1 - Heredity)

• Chromosome

  An umbrella term for something containing DNA (chromatin can be called chromosome, so as chromatids with a centromere)
• Cell division


  • Essential for organisms to grow, repair and/or reproduce
  • Passing of chromosomes from the parent to daughter cells
• Chromosomes


  Carry information for traits
• Heredity


  The process of traits passing from parents to offspring through chromosomes
• Genetics


  The scientific study of heredity and variation
• Genetic material


  All the material in an organism that stores genetic information
• DNA


  The genetic material stored in chromosomes, composed of hundreds of thousands of chemical subunits that act as a set of chemical instructions for the cell
• Gene


  A portion of a DNA molecule that carries the information to produce a particular trait of an organism, occupying a specific location on a chromosome called a locus
• A typical chromosome can carry hundreds of thousands of different genes at different loci
• Heredity


  Inheriting traits from parents, contained in segments of DNA called genes
• All eukaryotic cells have chromosomes, but with different number, size, or shapes
• Genome size and chromosome number are unrelated to complexity of organisms
• Chromosome sets in cells

  • Haploid (1 set, 23)
  • Diploid (2 sets, 46)
  • Polyploid (3 or more sets)
• Asexual reproduction


  A new individual produced from a single parent by cell division, resulting in genetically identical offspring
• Sexual reproduction


  Produced from the fusion of two sex cells (usually from two different parent organisms), resulting in genetically unique offspring
• Advantages of asexual reproduction

  • Don't have to seek a mate
  • Specialized mating behaviors and anatomy not required
• Disadvantages of asexual reproduction

  • Bad for environment changing
  • May be hard for species survival
• Advantages of sexual reproduction

  • Genetic variation beneficial to evolution and changing environment
  • Can support survival of the species
• Disadvantages of sexual reproduction

  • Specialized organs required to produce sex cells
  • Specialized mating calls or bright colors to attract mates, predators
  • May require loss of resources