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Genetics

Genetics. Which genes are expressed, and which are not…. Gregor Mendel. Father of genetics Austrian Monk Published his work in 1866 but was not rediscovered until 1900 Kept quantitative data on pea plants. Genetics : the scientific study of heredity

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Genetics

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  1. Genetics Which genes are expressed, and which are not…

  2. Gregor Mendel • Father of genetics • Austrian Monk • Published his work in 1866 but was not rediscovered until 1900 • Kept quantitative data on pea plants.

  3. Genetics: the scientific study of heredity • How genes (traits) are expressed (Genetics) • How genes (traits) are passed from one generation to the next (Inheritance)

  4. Mendel’s Laws • Traits come in pairs (1 Maternal egg, 1 Paternal sperm) • Some traits are dominant, while others are recessive. • Law of Independent Assortment: traits sort themselves independently. (Metaphase I) chromosomes separate. • Law of Segregation: traits separate during the formation of gametes. (Anaphase II). Chromatids separate.

  5. Genetics Terms • Gene: a section of DNA that codes for a protein that controls a trait. • Traits: distinguishing characteristics that are inherited (eye color).

  6. Genetic Terms • Alleles: alternate forms of a gene. • Example: bent vs. straight thumbs • Straight hair line vs. widow’s peak • Homozygous : a pair of alleles that are identical. “Purebred” RR or rr • Heterozygous:a pair of alleles that are different. Hybrid Rr

  7. Allele Description • Dominant: alleles that are always expressed when present. • Symbolize with CAPITAL LETTERS • Recessive: alleles that are only expressed when paired with another recessive allele. • Symbolize with lowercase letters

  8. Genotype: describing an organism in genes. • Symbolized with letters • Phenotype: describing an organism in physical characteristics. • Actual description of what you would see

  9. Complete Dominance A homozygous dominant pea, SS, is crossed with A homozygous recessive pea, ss.

  10. Complete Dominance

  11. Complete Dominance All offspring peas are Ss, heterozygous.

  12. Complete Dominance

  13. Complete Dominance The dominant allele completely hides the recessive allele. Recessive alleles are only expressed when they are homozygous (2 recessive genes and no dominant genes).

  14. Complete Dominance 2 heterozygous, Ss, peas can produce SS, Ss or ss offspring.

  15. Monohybrid Cross A cross of two individuals that only tests one trait.

  16. Punnett Squares Reginald Crundall Punnet • British Mathematician • Wrote the first popular Genetics book “Mendelism” • Created the Punnett Square

  17. Probability: the likelihood that something will occur. • Punnett Square:a diagram that helps visualize the possible offspring from a cross of two individuals.

  18. Tomato Plant Height (Tall or Short)

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