Mendelian Genetics

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Chapter 6

• Mendelian Genetics

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• Genetics the scientific study of heredity
• Gregor Mendel is said to be the father of
  genetics.
• Mendel used pea plants to study the inheritance
  of traits.

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• True-breeding plants that produce offspring
  identical to themselves.
• Parents that have different traits will produce
  hybrids.
• Hybrids are offspring of parents with different
  traits.

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Mendels Pea Traits
Traits Traits are specific characteristics
(like blue eyes or 5 fingers)
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• Genes are factors that are passed from one
  generation to the next. (From parents to
  offspring)
• Alleles are different forms of a gene (like
  purple or white flowers).

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Law of Dominance

• This principle states that some alleles are
  dominant and others are recessive.
• The dominant allele is represented by an
  uppercase letter.
• P purple flower
• The recessive allele is represented by a
  lowercase letter.
• p white flower

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• Dominant Trait that will hide or mask the
  recessive trait
• Recessive Trait that will show only when found
  with another recessive allele
• Genotype what the alleles are
• Phenotype observable characteristics

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• P Generation is the first parental generation.
• F1 is called the first filial generation or the
  first offspring when the P generation is crossed.
• F2 is called the second filial generation or the
  offspring from crossing the F1 generation.

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Mendels Law of Segregation

• Mendel wanted to know what happened to the
  recessive alleles.
• He allowed for F1 plants to self pollinate and
  this resulted in some F2 plants showing the
  recessive trait.
• The two alleles separate when organisms produce
  gametes, or sex cells. Each gamete carries a
  single copy of each gene.

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• Homozygous - Organisms that have two identical
  alleles for a particular trait
• Ex. TT or tt
• Heterozygous - Organisms that have two different
  alleles for a particular trait (Hybrids) Ex. Tt
• Punnett squares show
• Possible genotypes
• The alleles in the gametes of parents
• All possible results of a genetic cross

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Probability

• Probability is the likelihood that a specific
  event will occur.
• Flip a coin 100 times record the number of times
  it is heads _____ and tails_____
• Principles of probability can be used to predict
  the traits of offspring produced by genetic
  crosses

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Mendels Law of Independent Assortment

• Genes for different traits can segregate (on
  separate chromosomes) independently during the
  formation of gametes.
• Example Seed shape doesnt determine seed color.