1. Chapter 12 Gregor Mendel and his Peas

2. DNA can appear in 2 forms ______________ Spread out when cells are NOT dividing. _________________ Scrunched up in bundles as when cells divide. CHROMATIN CHROMOSOMES

3. Chromosome structure ______________________ 2 identical arms __________________ constricted area holds chromatids together __________________ PAIR 2 of each chromosome (one from mom; one from dad) SISTER CHROMATIDS CENTROMERE HOMOLOGOUS

5. Gregor Mendel Father of 1822-1884 Austrian monk Worked with peas

6. Why Peas? Visible traits Only 2 forms of each trait Cheap! Takes up little space Produce many offspring Short generation time

7. Genetics The study of how characteristics are passed on from one generation to the next.

8. Heredity The passing on of characteristics from parent to offspring.

9. Monohybrid Cross Mono = only 1 trait is crossed Use Punnett Squares Must have a KEY!!! –Example: GenotypePhenotype GGgreen Gggreen ggyellow

10. Punnett Squares Parent #2’s alleles Parent #1’s alleles

11. Vocabulary Alleles: a form of a trait. G, g Phenotype: description. Color, shape, etc. Genotype: the letters. GG, Gg, gg Homozygous: same letters GG and gg Heterozygous: different letters Gg 2 types of genotype alleles show

12. Vocabulary Dominant –trait that is ALWAYS shown. –(upper case letter) –Example: Green is shown in GG and Gg Recessive –trait that is ONLY shown when it is homozygous. –(lower case letter) –Example: Yellow is shown only in gg

13. 1.Phenotypes of parents? 2.Genotypes of parents? 3.Phenotype of child #1? 4.Genotype of child #1? 5.Genotypes of children #2 and #3? 6.Phenotypes of children #2 and #3? 7.Genotype of child #4? 8.Phenotype of child #4? GenotypePhenotype GGgreen Gggreen ggyellow Key: green Gg green GG Gg green gg yellow #1 #4#3 #2

14. Phenotypes? Genotypes? Phenotype Ratio? Genotype Ratio? What are the… All Tall 4 Tt 4:0 0:4:0 3 Tall, 1 Short 1 TT, 2 Tt, 1 Tt 3:1 1:2:1 2 Tall, 2 Short 2 Tt, 2tt 2:2 0:2:2

15. Peas

16. Practice Monohybrid Crosses! Vocabulary to remember Genotype: letters GG, Gg, gg Phenotype: description Green, yellow Homozygous: same lettersGG and gg Heterozygous: different lettersGg Dominant: large letterG Recessive: small letterg

17. Looking at Family Trees

18. Pedigree

19. Royal Pedigree

20. Dihybrid Cross Di = 2 traits are crossed 2 Steps!!! –Cross parents individually. (2 x 2) –Cross the crosses. (4 x 4)

22. ry RY 100% of offspring = _______ genotype _______________________ phenotype RrYy round & yellow

23. RYRyrYry RY Ry rY ry Sign of a heterozygous dihybrid cross is a _____________ ratio in offspring. 9:3:3:1 ____ Round & Yellow ____ Round & green ____ Wrinkled & yellow ____ wrinkled & green 9 3 3 1

24. Test Cross Used to tell what genes an organism has. ALWAYS cross the unknown with a homozygous recessive. Only 3 possible results: –gg x ____ *Get 100% green offspring. –gg x ____ *Get 50% green & 50% yellow offspring. –gg x ____ *Get 100% yellow offspring. GG Gg gg

25. Mendel’s Law of Segregation Chromosome pairs are separated (segregated) when gametes are formed. gamete- sex cells. (egg & sperm)

26. Mendel’s Law of Independent Assortment Alleles are distributed to gametes independently. gamete- sex cells. (egg & sperm)

27. EXAMPLES OF “SIMPLE MENDELIAN” INHERITANCE DOMINANTRECESSIVE Brown EyesBlue Eyes Brown EyesGreen Eyes Curly HairStraight Hair Brown HairBlond Hair Dark PigmentationLight Pigmentation Average IntellectGenius Average IntellectFeebleminded Tall StatureShort Stature DwarfismAverage Height Extra digits5 digits Widows PeakNo Widows Peak Free EarlobeAttached Earlobe

29. The End.