1. A. Where did I get these freckles? B. Why is my brother so athletic and I’m so clumsy? C. Why do diseases show up in some generations and not others?

2. The answer… Heredity!!!

3. Mating Game Activity

4. HEREDITY A.Heredity—the passing of traits from parents to offspring B.Traits—the physical or behavioral characteristics passed to offspring

5. MENDEL & HEREDITY For thousands of years people have noticed that offspring resembled their children…Could this man have the answer?

6. MENDEL & HEREDITY A.Gregor Mendel, an Austrian monk, studied garden peas for 14 years. B.He would cross “pure” plants of opposite traits and observe their offspring.

7. MENDEL & HEREDITY C. Gametes—male and female sex cells (sperm and egg) 1. Mendel chose pea plants because each plant has male and female gametes.

8. MENDEL & HEREDITY D. Pollination—the transfer of pollen grains (containing sperm) to the female reproductive organs in the same flower 1. Mendel used cross- pollination (2 flowers)

9. MENDEL & HEREDITY E. Fertilization—the joining of male and female gametes. F. Zygote—a fertilized cell 1. Every living thing begins as a zygote!

10. MENDEL & HEREDITY G. Hybrid—the offspring of parents that have different traits 1. Tall x Short H. Monohybrid Cross—only ONE trait is different

11. MENDEL & HEREDITY I. Mendel was a careful researcher 1. Studied one trait at a time 2. Used “pure” plant lines 3. Used a large # of plants and many trials

12. MENDEL’S RULES a)Genes are sections of DNA located on the chromosome chromosome b) Genes are like ice cream, alleles are the different flavors Aa

13. MENDEL’S RULES B. The Rule of Dominance 1. When one trait covers up another trait it is said to be “dominant” a) Write in capital letters b) AA

14. MENDEL’S RULES 2. The trait that is covered up is “recessive” a) Trait only shows up when 2 recessive alleles are inherited from parents b) Write in lower case letters b) aa

15. MENDEL’S RULES 3. When one dominant allele (A) and one recessive allele (a) is inherited, the dominant allele shows up a) AA=Tall b) aa=Short c)Aa=Tall

16. MENDEL’S LAWS C. The Law of Segregation 1. Since each gene has two alleles, it can produce two different gametes 2. The alleles separate 3. Male and female gametes pair up randomly creating 4 possible combinations

17. GENOTYPE A. Genotype—the combination of alleles in the organism 1. AA or Aa or aa 2. The letters!

18. GENOTYPE B. Homozygous—both alleles are dominant or recessive 1. AA or aa C. Heterozygous—one allele is recessive and one is dominant 2. Aa

19. PHENOTYPE A. Phenotype—the outward appearance or behavior of the organism 1. Tall or Short 2. What it looks like!

20. MENDEL’S EXPERIMENT A. Tall x Short 1. All tall plants were > 6 ft 2. All short plants were < 2ft 3. The original generation is called “P1” 4. See page 255

21. MENDEL’S EXPERIMENT B. Results: The offspring were ALL Tall!!! 1. This generation were called “F1”

22. MENDEL’S EXPERIMENT C. Next, he crossed the F1s D. Results: ¾ were Tall and ¼ were short (3:1 ratio) 1. The short plants reappeared from nowhere! 2. This generation was called “F2”

23. MENDEL’S RULES A. The Rule of Unit Factors 1. Each organism inherits one possibility for a trait from each parent 2. Alleles—Different form of a trait

24. PUNNETT SQUARES A. Punnett Squares are used to predict the probability of a genotype to occur

26. PUNNETT SQUARES B. Probability can be written as a fraction, ratio or percent 1. ¾, ¼ 2. 3:1 3. 75%, 25%

27. PUNNETT SQUARES C. Can also be used for dihybrid crosses (2 traits) _________________________ RR & Rr=round rr= wrinkled YY & Yy= yellow yy= green RY Ry rY ry RY Ry rY ry RRYY

28. MENDEL’S LAST LAW A. The Law of Independent Assortment 1. Genes for different traits, for example shape and color, are inherited independent from each other.

29. MENDEL’S LAST LAW 2. The two different genes have nothing to do with each other. 3. Exception: Unless the genes for the two traits are on the same chromosome!!!

30. REVIEW What is a hybrid? THE OFFSPRING OF PARENTS THAT HAVE DIFFERENT TRAITS/ALLELES

31. REVIEW What is the name for the parent generation? The offspring? P1F1

32. REVIEW What happens to a recessive trait when a dominant allele is present? IT DOES NOT SHOW UP!

33. REVIEW Give an example of a heterozygous organism using the letter Q. Qq

34. REVIEW What’s the difference between genotype and phenotype? G=combination of alleles P=the outward appearance

35. REVIEW If the results of your punnett square were 1 AA, 2 Aa and 1 aa, what is probability ratio? 1:2:1