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Understanding Genetics: The Pioneering Work of Gregor Mendel in Inheritance

Explore the groundbreaking contributions of Gregor Mendel, known as the "Father of Genetics," who established the foundational laws governing the inheritance of traits through his meticulous studies of pea plants. Mendel's work, conducted between 1856 and 1863, involved over 28,000 plants and revealed how offspring retain traits from their parents. Despite being overlooked for decades, his discoveries laid the groundwork for modern genetics, introducing key concepts such as alleles, genotypes, phenotypes, and genetic crosses.

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Understanding Genetics: The Pioneering Work of Gregor Mendel in Inheritance

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  1. All-Star Science Introduction to Genetics

  2. Father of Genetics Gregor Mendel(1822-1884) Responsible for the Laws governing Inheritance of Traits

  3. Gregor Johann Mendel • Austrian monk • Studied the inheritance of traits in pea plants • Developed the laws of inheritance • Mendel's work was not recognized until the turn of the 20th century

  4. Gregor Johann Mendel • Between 1856 and 1863, Mendel cultivated and tested some 28,000 pea plants • He found that the plants' offspring retained traits of the parents • Called the “Father of Genetics"

  5. Site of Gregor Mendel’s experimental garden in the Czech Republic

  6. Genetic Terminology • Trait - any characteristic that can be passed from parent to offspring. • Heredity - passing of traits from parent to offspring • Genetics - study of heredity

  7. Types of Genetic Crosses • There are different types of genetic crosses. We are going to be dealing with the simplest type. • Monohybrid cross - cross involving a single traite.g. flower color

  8. Designer “Genes” • Alleles - two forms of a gene (dominant & recessive) • Dominant - stronger of two genes expressed in the hybrid; represented byacapital letter (R) • Recessive - gene that shows up less often in a cross; represented by alowercase letter (r)

  9. More Terminology • Genotype - gene combination for a trait(e.g. RR, Rr, rr) • Phenotype - the physical feature resulting from a genotype(e.g. red, white)

  10. Genotype & Phenotype in Flowers Genotype of alleles:R= red flowerr= yellow flower All genes occur in pairs, so 2alleles affect a characteristic Possible combinations are: GenotypesRRRrrr PhenotypesRED RED YELLOW

  11. Genotypes • Homozygousgenotype - gene combination involving 2 dominant or 2 recessive genes (e.g. RR or rr);also calledpure  • Heterozygousgenotype - gene combination of one dominant & one recessive allele    (e.g. Rr); also calledhybrid

  12. Punnett Square Used to help solve genetics problems

  13. Genes and Environment Determine Characteristics

  14. Monohybrid Crosses

  15. Monohybrid Cross • Trait: Seed Shape • Alleles: R – Round r – Wrinkled • Cross: RoundseedsxWrinkled seeds • RRxrr Genotype:Rr Phenotype:Round GenotypicRatio:All alike PhenotypicRatio: All alike r r Rr Rr R R Rr Rr

  16. Genetic Practice Problems

  17. Cross these two plants. t t T T • tall (TT) x dwarf (tt) pea plants

  18. Solution: t t produces the F1 generation Tt Tt T Tt Tt T All Tt = tall (heterozygous tall) tall (TT) vs. dwarf (tt) pea plants

  19. Breed the F1 generation T t T t • tall (Tt) vs. tall (Tt) pea plants

  20. Solution: T t produces the F2 generation Tt TT T 1/4 (25%) = TT 1/2 (50%) = Tt 1/4 (25%) = tt Tt tt t 1:2:1 genotype 3:1 phenotype tall (Tt) x tall (Tt) pea plants

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