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Let’s review!

Let’s review!. Alleles are found at the same locus (place) on homologous chromosomes (remember pairs). or. YY. yy. Homozygotes (pure breds). Yy. Heterozgote (hybrid). yy. Recessive Allele is only expressed in a homozygote. or. Yellow. Green. Phenotype (appearance).

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Let’s review!

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  1. Let’s review! • Alleles are found at the same locus (place) on homologous chromosomes (remember pairs)

  2. or YY yy • Homozygotes (pure breds)

  3. Yy • Heterozgote (hybrid)

  4. yy • Recessive Allele is only expressed in a homozygote

  5. or Yellow Green • Phenotype (appearance)

  6. Genotype (combination of alleles) Yy YY yy or or

  7. or YY yy • Monohybrid Cross - one characteristic is used Key: Y=yellow y=green

  8. or YYSS yyss • Dihybrid Cross - two characteristics are used Key: Y=yellow y=green S=smooth s=wrinkled

  9. Dihybrid Crosses Chapter 11-3 Exploring Medelian Genetics

  10. Do genes separate? • Yes, genes separate independently, even if you have more than one type of gene. • This help us in solving dihybrid crosses (crosses involving two traits)

  11. Let’s work a problem!!!! Key: T=tall pea plant t=short pea plant R=round seed shape r=wrinkled seed shape 1) Write a key

  12. 2) Write the genotype of the parents as a cross and label them as P (for parent generation) Key: T=tall pea plant t=short pea plant R=round seed shape r=wrinkled see shape TTRR x ttrr P

  13. Take the Outside letters in each parentheses and put them in a circle to represent the gamete. Take the Inside letters in each parentheses and put them in a circle to represent the gamete. Take the first letters in each parentheses and put them in a circle to represent the gamete. Each parent will have four gametes. Take the Last letters in each parentheses and put them in a circle to represent the gamete. Key: T=tall pea plant t=short pea plant R=round seed shape r=wrinkled see shape 3) Show what alleles are available from the gametes of the parents USING THE FOIL METHOD NOw use the FOIL method to make gametes…. Write parenthesis around the different characteristics in each parent. TTRR x ttrr (TT)(RR) x (tt)(rr) Take this allele Take this allele Take this allele Take this allele And this allele And this allele And this allele And this allele TR TR TR TR P Combined to make this gamete Combined to make this gamete Combined to make this gamete Combined to make this gamete The foil method goes: • F = First • O = Outside • I = Inside • L = Last

  14. Key: T=tall pea plant t=short pea plant R=round seed shape r=wrinkled see shape 3) Show what alleles are available from the gametes of the parents USING THE FOIL METHOD NOw use the FOIL method to make gametes for the second parent ( r r ) ) ( (TT)(RR) x t t TR TR TR TR tr tr tr tr REMEMBER!!! The foil method goes: • F = First • O = Outside • I = Inside • L = Last

  15. Draw a Punnett square for dihybrid cross…you will need 4 columns and 4 rows Key: T=tall pea plant t=short pea plant R=round seed shape r=wrinkled see shape • Draw a Punnett square for a dihybrid cross ( r r ) ) ( (TT)(RR) x t t TR TR TR TR tr tr tr tr

  16. Fill in the first parent’s gametes on the left hand side and the second on top.. Key: T=tall pea plant t=short pea plant R=round seed shape r=wrinkled see shape • Put the gametes on the square ( r r ) ) ( (TT)(RR) x t t TR TR TR TR tr tr tr tr

  17. Be consistent…Keep the first two letters the same throughout the square… ex: T’s 1st and R’s second… Fill in the boxes… Keep the letters together…Example: T’s with T’s and R’s with R’s… Key: T=tall pea plant t=short pea plant R=round seed shape r=wrinkled see shape • Fill in the boxes with the correct genotype ( r r ) ) ( (TT)(RR) x t t tr tr tr tr TR TtRr TtRr TtRr TtRr TR TtRr TtRr TtRr TtRr TR TtRr TtRr TtRr TtRr TR TtRr TtRr TtRr TtRr

  18. Key: T=tall pea plant t=short pea plant R=round seed shape r=wrinkled see shape • Write the genotype and phenotype for the F1 generation ( r r ) ) ( (TT)(RR) x t t Genotype of F1 : tr tr tr tr 16 = TtRr TR TtRr TtRr TtRr TtRr Phenotype of F1 : 16 = tall and round seed shape TR TtRr TtRr TtRr TtRr TR TtRr TtRr TtRr TtRr TR TtRr TtRr TtRr TtRr F1

  19. Take two from the F1 generation to cross to find out the genotype and phenotype of the F2 generation (all the same, choose two) Key: T=tall pea plant t=short pea plant R=round seed shape r=wrinkled see shape ( r r ) ) ( (TT)(RR) x t t Genotype of F1 : tr tr tr tr 16 = TtRr TR TtRr TtRr TtRr TtRr Phenotype of F1 : 16 = tall and round seed shape TR TtRr TtRr TtRr TtRr TR TtRr TtRr TtRr TtRr TR TtRr TtRr TtRr TtRr F1

  20. ( R r ) x ( R r ) Key: T=tall pea plant t=short pea plant R=round seed shape r=wrinkled see shape ) ( ) ( T t T t F1 TR Tr tR tr • Follow the same steps to cross the F1 generation and complete the F2 generation REMEMBER!!! The foil method goes: • F = First • O = Outside • I = Inside • L = Last

  21. ( R r ) x ( R r ) Key: T=tall pea plant t=short pea plant R=round seed shape r=wrinkled see shape ) ( ) ( T t T t F1 TR Tr tR tr TR Tr tR tr

  22. ( R r ) x ( R r ) Key: T=tall pea plant t=short pea plant R=round seed shape r=wrinkled see shape ) ( ) ( T t T t F1 TR Tr tR tr TR Tr tR tr TR Tr tR tr TR TTRR TTRr TtRR TtRr Tr TTRr TTrr TtRr Ttrr tR TtRR TtRr ttRR ttRr tr TtRr Ttrr ttRr ttrr F2

  23. Key: T=tall pea plant t=short pea plant R=round seed shape r=wrinkled see shape ( R r ) x ( R r ) ) ( ) ( T t T t F1 TR Tr tR tr TR Tr tR tr Genotype of F2 : 1 =TTRR TR Tr tR tr 2 =TTRr =TtRR 2 TR TTRR TTRr TtRR TtRr =TtRr 4 1 =TTrr Tr =Ttrr 2 TTRr TTrr TtRr Ttrr =ttRR 1 2 =ttRr tR TtRR TtRr ttRR ttRR ttRr 1 =ttrr tr TtRr Ttrr ttRr ttrr F2

  24. Key: T=tall pea plant t=short pea plant R=round seed shape r=wrinkled see shape ( R r ) x ( R r ) ) ( ) ( T t T t F1 TR Tr tR tr TR Tr tR tr Genotype of F2 : 1 =TTRR 2 =TTRr TR Tr tR tr =TtRR 2 =TtRr 4 1 =TTrr TR =Ttrr 2 TTRR TTRr TtRR TtRr =ttRR 1 2 =ttRr 1 =ttrr Tr TTRr TTrr TtRr Ttrr Phenotype of F2 : 9 =tall and round seed shape 3 =tall and wrinkled seed shape tR TtRR TtRr ttRR ttRr 3 =short and round seed shape 1 =short and wrinked seed shape tr TtRr Ttrr ttRr ttrr F2 Wow…you did it!!! Good job…. All you have to do is follow the steps!

  25. And now for something really original! Another Dihybrid problem… On your own!!!! • In aliens from outer space, having ANTENNAE is dominant over having horns AND GREEN skin is dominant over purple skin. • Key: • A=antennae • a= horns • G=green • g=purple

  26. Key: • A=antennae • a= horns • G=green • g=purple • Cross a homozygous antennae alien that is homozygous green with a homozygous horned alien that is homozygous purple. • What would the parent’s genotype look like? AAGG x aagg p

  27. Key: • A=antennae • a= horns • G=green • g=purple • Cross a homozygous antennae alien that is homozygous green with a homozygous horned alien that is homozygous purple. (AA)(GG) x (aa)(gg) p AAGG x aagg p • Write the parenthesis around parents alleles

  28. Key: • A=antennae • a= horns • G=green • g=purple • Cross a homozygous antennae alien that is homozygous green with a homozygous horned alien that is homozygous purple. (AA)(GG) x (aa)(gg) p ag ag ag ag AG AG AG AG REMEMBER!!! The foil method goes: • F = First • O = Outside • I = Inside • L = Last

  29. Key: • A=antennae • a= horns • G=green • g=purple • Cross a homozygous antennae alien that is homozygous green with a homozygous horned alien that is homozygous purple. (AA)(GG) x (aa)(gg) p AG AG AG AG ag ag ag ag ag ag ag ag Genotype of F1 : 16 = AaGg AG AaGg AaGg AaGg AaGg Phenotype of F1 : AG AaGg AaGg AaGg AaGg 16 = antennae and green AG AaGg AaGg AaGg AaGg AG AaGg AaGg AaGg AaGg F1

  30. Key: • A=antennae • a= horns • G=green • g=purple • Cross a heterozygous antennae alien that is heterozygous green with a heterozygous antennae alien that is heterozygous green • What would the parent’s genotype look like? AaGg x AaGg F1

  31. Key: • A=antennae • a= horns • G=green • g=purple • Cross a heterozygous antennae alien that is heterozygous green with a heterozygous antennae alien that is heterozygous green . (AA)(GG) x (aa)(gg) F1 AaGg x AaGg p • Rewrite the parents with parenthesis

  32. Key: • A=antennae • a= horns • G=green • g=purple • Cross a homozygous antennae alien that is homozygous green with a homozygous horned alien that is homozygous purple. (Aa)(Gg) x (Aa)(Gg) AG Ag aG ag AG Ag aG ag REMEMBER!!! The foil method goes: • F = First • O = Outside • I = Inside • L = Last

  33. Key: • A=antennae • a= horns • G=green • g=purple • Cross a homozygous antennae alien that is homozygous green with a homozygous horned alien that is homozygous purple. (Aa)(Gg) x (Aa)(Gg) AG Ag aG ag AG Ag aG ag AG Ag aG ag AG AAGG AAGg AaGG AaGg Ag AAGg AAgg AaGg Aagg aG AaGG AaGg aaGG aaGg ag AaGg Aagg aaGg aagg F1

  34. Key: • A=antennae • a= horns • G=green • g=purple • Cross a homozygous antennae alien that is homozygous green with a homozygous horned alien that is homozygous purple. (Aa)(Gg) x (Aa)(Gg) F1 AG Ag aG ag AG Ag aG ag Genotype of F1 : AG Ag aG ag 1 =AAGG 2 =AAGg AG AAGG AAGg AaGG AaGg =AaGG 2 =AaGg 4 Ag AAGg AAgg AaGg Aagg 2 =Aagg =AAgg 1 =aaGG 1 aG AaGG AaGg aaGG aaGg 2 =aaGg 1 =aagg ag AaGg Aagg aaGg aagg F2

  35. Key: • A=antennae • a= horns • G=green • g=purple Genotype of F1 : 1 =AAGG 2 =AAGg =AaGG 2 =AaGg 4 2 =Aagg =AAgg 1 =aaGG 1 2 =aaGg 1 =aagg • Cross a homozygous antennae alien that is homozygous green with a homozygous horned alien that is homozygous purple. (Aa)(Gg) x (Aa)(Gg) p AG Ag aG ag AG Ag aG ag AG Ag aG ag AG AAGG AAGg AaGG AaGg Ag AAGg AAgg AaGg Aagg Phenotype of F1 : 9 =antennae and green aG AaGG AaGg aaGG aaGg 3 =antennae and purple 3 =horns and green ag AaGg Aagg aaGg aagg 1 =horns and purple F1

  36. Dihybrid Homework Problem • In aliens from outer space, having ANTENNAE is dominant over having horns AND GREEN skin is dominant over purple skin. • Cross an alien from outer space that is Homozygous antennae and heterozygous green with another that is Homozygous horns and heterozygous green. • Show the genotype and phenotype

  37. http://biology.clc.uc.edu/courses/bio105/geneprob.htm

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