Genetics

• Genetics


  The scientific study of heredity
• Heredity


  The passing of physical characteristics from parents to offspring
• DNA


  Contains your genes; found in the nucleus
• Genes


  The factor that controls a trait; found on chromosomes
• Traits


  The different forms of a characteristic (ex. dimples: present or absent)
• Alleles


  The letters that represent the different forms of a gene (dimples: D = present; d = absent)
• Dominant


  The traits that overshadows and is expressed (capital letter)
• Recessive


  The trait that hides in the background (lowercase letter)
• Genotype


  Combination of alleles (such as DD, Dd, dd)
• Phenotype


  The physical appearance of a trait (ex. dimples or no dimples)
• Homozygous


  Two alleles/letters for one trait that are the same (ex: DD or dd)
• Heterozygous


  Two alleles/letters for one trait that are different (ex. Dd)
• Gregor Johann Mendel was an Austrian monk and math & science teacher
• Mendel's experiments with peas led him to being named the "FATHER OF GENETICS"
• Mendel's peas


  • Mendel chose to study peas because they can self-pollinate or cross pollinate
  • This means a pea plant can produce offspring by itself to create a purebred (or true-breeding plant) with identical traits or a pea can cross with another pea plant to produce offspring with mixed traits from both parent plants
• Mendel's pea experiments


  1. Mendel studied 1 trait at a time

  2. Mendel took pollen from a true-breeding tall pea plant and cross-pollinated it with a true-breeding short pea plant

  3. This formed a hybrid: offspring of parents that have different forms of a trait
• Some Pea Traits that Mendel Studied

  • Round seed
  • Wrinkled seed
  • Green seed
  • Tall plant
  • Short plant
• Genes


  The set of instructions for inherited traits
• Alleles


  The different forms of a gene
• Genes for height

  • Genes for tall plants (TT, Tt)
  • Genes for short plants (tt)
• Dominant trait


  A trait that shows up more often
• Recessive trait


  A trait that doesn't show up again until later generations
• For each of the 7 traits that Mendel studied in peas, there is a dominant allele and a recessive allele
• If a plant inherits both a dominant allele and a recessive allele (hybrid), the dominant allele masks the recessive allele
• Homozygous


  An organism with two identical alleles for a trait
• Heterozygous


  An organism that has two different alleles for a trait
• 
  

  A dominant allele is expressed over a recessive allele
• 
  

  A recessive allele is only expressed when there are two copies present
• 7 Traits of the Pea Plant


  • Round seed
  • Wrinkled seed
  • Green seed
  • Tall plant
  • Short plant
• Dominant + Dominant = Dominant
• Dominant + Recessive = Dominant
• Recessive + Dominant = Dominant
• Recessive + Recessive = Recessive
• Punnett Squares


  Created by Reginald Punnett to predict the probability and possible genotypes in offspring
• Probability


  The likelihood that a particular event will occur
• Crossing a homozygous recessive mother and a heterozygous father for black/brown hair

  There is a 50% chance the offspring will have black hair and a 50% chance they will have brown hair
• GENETICS the scientific study of

  heredity
• HEREDITARY the passing of

  physical characteristics from parents

  to offspring.
• DNA contains your genes; found in

  the nucleus
• TRAITS the different forms of a

  characteristic (ex. dimples: present or

  absent)