1. The study of heredity – how characteristics are passed on from parents to offspring Genetics

2. Setting the Stage Mike the mouse has black eyes. Mindy has red eyes. Mindy Mike

3. Mike and Mindy have 10 kids. They all have black eyes. MindyMike X 10 Black-eyed kids

4. Mike and Mindy are the Parental (P) Generation Their kids are the First Filial (F1) Generation MindyMike X 10 Black-eyed kids

5. Two of Mike and Mindy’s kids (each with black eyes) have their own 12 kids! These kids are the Second Filial (F2) Generation. F1 Kid X ? MindyMike X

6. 9 of the F2 kids have black eyes, but three have red eyes (like Mindy – AKA Grandma) What’s going on? F1 Kid X MindyMike X 9 F2 Kids3 F2 Kids

7. Genes control the traits (characteristics) we observe A gene is a specific portion of DNA found on a specific chromosome For each trait, you have two copies of the gene - one from mom and one from dad Trait = eye color Eye color is controlled by a gene

8. Alternate versions of the genes  Alleles One allele in a pair may prevent the other from having an effect –dominant allele –represented by capital letter (B) The gene for eye color may code for black or red eyes. Black eyes and red eyes are alleles for eye color

9. The trait that doesn’t show up when the dominant allele is present: –recessive allele –represented by a lower-case letter (b) Always use the same letter of the alphabet for the same gene – even for different alleles Dad has one dominant allele (B) for black and one recessive allele (b) for red.

10. The recessive allele has no effect on the appearance of an organism when it is paired with a dominant allele Black (BB) x Red (bb)  Black (Bb)

11. Definitions Genotype - genetic makeup of an organism –The alleles it inherited –Genotype for black eyes = BB or Bb Phenotype - appearance of an organism –Phenotype of BB or Bb = black eyes

12. Homozygous - both alleles alike for particular trait –BB = homozygous dominant –bb = homozygous recessive Heterozygous = alleles different for particular trait (AKA hybrid) –Bb = heterozygous

13. Monohybrid Crosses Cross involving one pair of contrasting traits black eyes X red eyes Black eyes is dominant to red eyes Both parents are homozygous for eye color Use Punnett square to predict the probability of particular outcomes

14. Punnett Square P 1 : BB x bb(black x red) 1. Draw a 2 x 2 box

15. P 1 : BB x bb

16. Punnett Square P 1 : BB x bb(black x red) 1.Draw a 2 x 2 box 2.Determine type of gametes P 1 generation can make Meiosis I

17. P 1 : BB x bb B B bb

18. Punnett Square P 1 : BB x bb 1.Draw a 2 x 2 box 2.Determine type of gametes P 1 generation can make 3.Combine alleles and count F 1 varieties

19. P 1 : BB x bb B B bb Bb F 1 genotype: 4/4 Bb F 1 phenotype: 4/4 Black

20. P 1 : BB x Bb B B bB BB Bb F 1 genotype: 2/4 BB 2/4 Bb F 1 phenotype: 4/4 Black

21. P 1 : BB x Bb B B bB BB Bb F 1 genotype: 2 BB: 2 Bb 1 BB: 1 Bb F 1 phenotype: All black

22. P 1 : Bb x Bb B b bB BB Bb bb F 1 genotype: 1 BB:2 Bb:1 bb F 1 phenotype: 3 black:1 red

23. Test Cross Know phenotype, but not genotype Black fur (B) is dominant over white fur (b) Is genotype of a black mouse BB or Bb?

24. Cross unknown black mouse (BB or Bb) with a white mouse (bb) B_ x bb

25. BB x bbBb x bb b b Bb Bb Bb Bb bb bb 100% Black50% White BBBB BbBb

26. If all offspring are black... –BB x bb  100% Bb If half of offspring are white... –Bb x bb  50% Bb, 50% bb

27. “Apparently he learned about heredity today.”