1. Review Questions ________________ is the scientific study of heredity. A) Traits B) Alleles C) Genetics D) Geneology

2. Review Questions A behavioral or physical characteristic is a ___________. A) Trait B) Gene C) Allele D) Chromosome

3. Review Questions Which of the following genotypes is homozygous dominant? A) AB B) aa C) Aa D) AA

4. Review Questions Which of the following genotypes is heterozygous? A) AA B) aa C) Aa D) AB

5. Review Questions Every gene has ____ alleles? A) one B) two C) three D) four

6. Review Questions Who is the “Father of Genetics”? A) Isaac Newton B) Robert Hooke C) Gregor Mendel D) Henry Lackes

7. Review Questions Which of the following is NOT a phenotype? A) eye color B) height C) genes D) attached earlobes

8. Review Questions Write down the recessive allele in the genotype Rr. r (recessive alleles are always lower-case!)

9. Dominant & Recessive Practice TT - Represent offspring with ______ hair T – straight hair t - curly hair Straight hair

10. Dominant & Recessive Practice tt - Represents offspring with ______ hair T – straight hair t - curly hair Curly hair

11. Dominant & Recessive Practice Tt - Represent offspring with _____ hair T – straight hair t - curly hair Straight hair

12. Punnett Squares Notes

13. Punnett Squares Punnett Square – Diagram showing the gene combinations that might result from a genetic cross Used to calculate the probability of inheriting a particular trait Probability – The chance that a given event will occur

14. Punnett Square Parent Offspring

15. How to Complete a Punnett Square

16. Yy x Yy When 2 heterozygous genotypes are crossed, a parent can give contribute either a recessive or a dominant allele to the offspring. Y-Yellow y-white Genotype: 1:2:1 (YY:Yy:yy) Phenotype: ¾ (75%) Yellow ¼ (25%) White

17. How to Make a Punnett Square! Give the genotype and phenotype for the following cross: TT x tt (T = Tall and t = Short)

18. TT x tt Step One: Set Up Punnett Square (put one parent on the top and the other along the side)

19. TT x tt Step Two: Complete the Punnett Square by crossing each male and female gamete (to form a possible zygote).

20. TT x tt Step Three: Calculate the genotype and phenotype (remember that each box is 25%) Genotype: 4 - Tt Phenotype: 100% Tall

21. You Try It Now! Give the genotype and phenotype for the following cross: Tt x tt Genotype: Phenotype: Tt = 50% tt = 50% 50% Tall 50% Short:

22. Some Terminology P 1 – Original parents F 1 – First generation F 2 – Second generation P 1 X P 1 = F 1 F 1 X F 1 = F 2

23. Incomplete Dominance Incomplete Dominance - Situation in which one allele is not completely dominant over another. Example – Red and white flowers are crossed and pink flowers are produced.

24. Codominance Codominance - Situation in which both alleles of a gene contribute to the phenotype of the organism. Example – A solid white cow is crossed with a solid brown cow and the resulting offspring are spotted brown and white (called roan). +

25. Multiple Alleles Multiple Alleles- Three or more alleles of the same gene. Even though three or more alleles exist for a particular trait, an individual can only have two alleles - one from the mother and one from the father.

26. Examples of Multiple Alleles 1. Coat color in rabbits is determined by a single gene that has at least four different alleles. Different combinations of alleles result in the four colors you see here.

27. Examples of Multiple Alleles 2. Blood Type – 3 alleles exist (I A, I B, and i), which results in four different possible blood types 3. Hair Color – Too many alleles exist to count There are over 20 different shades of hair color.

28. Multiple Alleles There Are Always Multiple Alleles! Genetic inheritance is often presented with straightforward examples involving only two alleles with clear-cut dominance. This makes inheritance patterns easy to see. But very few traits actually only have two alleles with clear-cut dominance. As we learn more about genetics, we have found that there are often hundreds of alleles for any particular gene. We probably know this already - as we look around at other people, we see infinite variation.

29. Polygenic Trait Polygenic Trait - Trait controlled by two or more genes. Polygenic traits often show a wide range of phenotypes. Example: The wide range of skin color in humans comes about partly because more than four different genes probably control this trait.