2. Mendel and Meiosis Learning Goal: predict possible outcomes of various genetic combinations such as monohybrid crosses

3. Gregor Mendel  Heredity  Heredity is the passing of characteristics from parents to offspring.  Genetics  Genetics is the study of heredity or how those traits are inherited. Father of Genetics.  Gregor Mendel was the first person to succeed in predicting how traits were inherited thus he became known as the Father of Genetics.

4. Gregor Mendel GGregor Mendel is best known for his study of p pp pea plants. HHe used pea plants because they have 2 distinct sex cells called g gg gametes. MMendel pollinated the flowers himself by transferring the male pollen to the stigma of the flower ( (( (pollination).

5. Pollen

6. fertilization Uniting of the male and female gametes is called fertilization.

7. cross-pollinated  Mendel cross-pollinated pea plants in order to study the various traits: Dominant Dominant: the trait that was observed Recessive Recessive: the trait that disappeared.

8. Genotypes and Phenotypes PPPPhenotype – the way that the organism l ll looks and behaves. Pheno (physical) type (model) GGenotypes – the combination of alleles (genes) in the organism. Gen (birth) type (model)

9.  Allele  Allele – the different forms of a gene ex: Blue eyes or Brown eyes  Alleles can be dominant or recessive Dominant Dominant  The trait covers up (masks) the recessive trait  Symbol is a capital letter (T) Recessive Recessive  The trait is masked by the dominant allele  Symbol is a lowercase letter (t)

10. Genotypes and Phenotypes  Phenotype  Genotype Alleles Alleles

11. Genotypes and Phenotypes  Homozygous dominant: Homo (same)  Homozygous recessive:  Heterozygous: Hetero (different)

12. Crossing traits  Hybrid  Hybrid: a cross between plants with different traits like tall and short. monohybrid  Mendel’s first cross he called a monohybrid cross. (Mono means one) dihybrid  Later Mendel began crossing plants with 2 traits. These crosses were called dihybrid crosses. homozygous recessive  Testcross: Breeding an individual of unknown genotype to a homozygous recessive individual to reveal the unknown genotype

13. Parent generation Filial (son or daughter) generation 2 nd Filial generation Grandchildren Children Parents

14.  Law of segregation: segregate (separate) gametes  Law of segregation: the 2 alleles for each trait (on homologous chromosomes)will segregate (separate) with the formation of the gametes during meiosis. Mendel’s Laws of Inheritance

15.  Law of independent assortment: Each trait (or gene) is inherited independently of the other traits  Law of independent assortment: Each trait (or gene) is inherited independently of the other traits.  In other words, all blondes do not have blue eyes.

16. Punnett Squares Punnett  In 1905, Reginald Punnett, an English biologist, devised a shorthand way of predicting the outcomes of the various crosses.  These are called Punnett squares.

17. Monohybrid crosses Genotypes Phenotypes Bb: 100% Bb100% White B: White b: Black BB bb BbBb BbBb BbBbBbBb B B b b gametes

18. Monohybrid crosses Genotypes Phenotypes BB: 25% Bb: 50% bb: 25% White: 75% (BB and Bb) black: 25% B: White b: Black BBbBb BbBbb Genotypic ratio 1:2:1 Phenotypic ratio 3:1 Bb B b gametes

19. Monohybrid crosses Genotypes Phenotypes BB: 0% Bb: 50% bb: 50% Genotypic ratio 0:1:1 50% White 50% Black Phenotypic ratio 1:1 BB: White bb: Black Bb bb B b b b Bb bb Bbbb gametes