Mendel

1. Mendel Chapter 9-1

2. Heredity • Heredity: transmission of characteristics from parent to offspring

3. Probability probability: likelihood an event will happen and can be expressed as percentages, fractions, or decimals Probability = # of times an event is expected to occur number of chances for the event to occur

4. Probability EX. 225 Black mice AND 25 white mice White mice appeared 25 times Total number of mice was 250 Probability (of getting a white mouse)=

5. Probability EX. 225 Black mice AND 25 white mice White mice appeared 25 times Total number of mice was 250 Probability (of getting a white mouse)= 25/250 = = 0.10 OR 10%

6. Probability EX. 225 Black mice AND 25 white mice White mice appeared 25 times Total number of mice was 250 Probability (of getting a white mouse)= 25/250 = = 0.10 OR 10% What is the probability of getting a black mouse? Write answers on whiteboard

7. Mendel Mendel’s Peas • Observed 7 characteristics • Observed 2 contrasting traitswithin each characteristic EX. CHARACTERISTIC: flower color TRAIT: White or purple

8. Mendel’s Experiment • Step One: • Self-pollinated white flowers with white flowers for many generations • Self-pollinated purple flowers for make generations

9. Mendel’s Experiment • Step One: • Self-pollinated white flowers with white flowers for many generations • Self-pollinated purple flowers for make generations  ensures he has created pure traits • These flowers are called the P1 generation

10. Mendel’s Experiment, cont. • Step Two • Cross-pollinated a purple flower and white flower from the P1 generation

11. Mendel’s Experiment, cont. • Step Two • Resulting plants (first filial F1 generation) ALL had purple flowers

12. Mendel’s Experiment, cont. • Step Three • Cross-pollinated the F1 generation

13. Mendel’s Experiment, cont. • Step Three • Resulting plants (F2 generation) had many purple flowers and a few white flowers a ratio of 3:1 Trait for white had been “hidden” in the F1 generation, it did not disappear. 

14. P1 Generation Purple flowers P1 Generation White flowers X F1 Generation Purple flowers Self-pollination Summary of Mendel’s Experiment F2 Generation Purple flowers (705) White flowers (224)

15. He began to observe patterns- Each cross yielded similar ratios in F2 generation (3/4 had purple, and 1/4 white)

16. Mendel’s Results and Conclusions • Recessive and Dominant Traits • Dominant traits masked recessive traits • Example: Purple color was dominant to white since it “masked” the white color.

17. Mendel’s Results • Gene( DNA located on a chromosome) codes for a characteristic(ie flower color) • Different forms of a gene = allele (purple or white)

18. Mendel’s Results • Gene( DNA located on a chromosome) codes for a characteristic(ie flower color) • Different forms of a gene = allele (purple or white) • Letters used to represent alleles dominant trait capitalized (purple = P) recessive lower case (white = p)

19. Genotypes and Phenotypes • Genotype: alleles an organism inherits EX: PP Pp pp • Phenotypes: physical appearance due to the genotype EX: PP (purple) Pp (purple) pp (white)

20. Homozygous vs. Heterozygous • Homozygous: both alleles are alike (PP or pp) • Heterozygous: alleles are different (Pp)

21. Rules • Law of segregation: paired factors separate during meiosis (formation of gametes)

22. Rules Law of independent assortment: alleles sort independently of one another (not all dominant appeared together)

23. Whiteboard PracticeWrite the word each statement defines • Different forms of a gene (alleles or genotypes)

24. Whiteboard PracticeWrite the word each statement defines • Capital letters are used to represent this (dominant or recessive traits)

25. Whiteboard PracticeWrite the word each statement defines • The combination of alleles an individual inherits (genotype or phenotype)

26. Whiteboard PracticeWrite the word each statement defines • PP or pp (homozygous or heterozygous)