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Genetics

Genetics . Probability and Punnet Squares. Objectives. By the end of class you will know: How to indicate the difference between dominant and recessive alleles The definitions of heterozygous and homozygous The definitions of genotype and phenotype. Vocabulary . Gene :

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Genetics

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  1. Genetics Probability and Punnet Squares

  2. Objectives By the end of class you will know: How to indicate the difference between dominant and recessive alleles The definitions of heterozygous and homozygous The definitions of genotype and phenotype

  3. Vocabulary • Gene: • Found on a chromosome in a specific location called a locus • Allele: • Example: the gene for pea height has two alleles: Tall or Short

  4. A dominant allele will always mask a recessive allele.

  5. Vocabulary • Dominant: Alleles that are always expressed. A CAPITAL LETTER used to show a dominant allele • Example: Tongue Rolling • Tongue Rolling: Dominant • Non-Tongue Rolling: Recessive When a person has both alleles, Tongue Rolling and Non-Tongue Rolling, the person will always be a ____________________________

  6. Vocabulary • Recessive: Alleles that are only expressed when paired with another recessive allele. A lowercase letter represents the recessive allele. • Example: Hitchhiker’s thumb • Straight thumb = Dominant • Hitch-hiker’s thumb = Recessive When a person has both recessive alleles, the person will have a _____________________ thumb.

  7. Vocabulary All organisms have two copies of each gene, one contributed by the father, the other contributed by the mother. • Homozygous: • Example: • Heterozygous: • Example:

  8. Two different alleles are present (heterozygous) for pea shape, round and wrinkled. Round is dominant and wrinkled is recessive. • Using the letter R/r to show pea shape. How would this be written?

  9. Vocabulary • Genotype: • Describing an organism in terms of the individual’s genes • Example: Pea Shape - Wrinkled (R) or Non-wrinkled (r) • Genotype Possibilities: RR – wrinkled pea Rr– wrinkled pea Heterozygous rr – non-wrinkled

  10. Vocabulary • Phenotype: • Example: Pea Shape (Wrinkled or Non-Wrinkled) • Phenotype Possibilities • Wrinkled • Round ** Use the genotypes to determine the phenotypes

  11. Genetics and Probability • The likelihood that a particular event will occur is called probability. Example: Consider flipping a coin Landing: Heads UP or Tails UP The probability of landing heads? The probability of landing 3 heads in a row?

  12. Penny Flipping Lab

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