Inheritance Why Offspring Resemble their Parents But Not

Inheritance

Why Offspring Resemble their Parents

But Not Exactly Why?

Variety • Gamete Variety: Meiosis • Sexual Reproduction: ½ genes from each parent Parent Cells R r y All round-yellow seeds (Rr. Yy) Y Gametes 4 varieties 1 RY 4 1 ry 4 1 r. Y 4 1 Ry 4

Family Can you tell which kids belong to which parents?

Removed stamens from purple flower. White Stamens Parents (P) Carpel Purple Transferred pollen from stamens of white flower to carpel of purple flower. Experiment With Plants Sperm from white flower Egg of purple flower

White Removed stamens from purple flower. Stamens Parents (P) Carpel Purple Transferred pollen from stamens of white flower to carpel of purple flower. Pollinated carpel matured into pod. Offspring Develop

White Removed stamens from purple flower. Stamens Parents (P) Carpel Purple Transferred pollen from stamens of white flower to carpel of purple flower. Pollinated carpel matured into pod. Planted seeds from pod. Offspring (F 1) Why? Offspring All Purple

Genotype VS Phenotype • Letters represent different expressions of a gene (alleles) • Capital letter=Dominant allele • lower case letter=recessive allele Genotype (Words) Genotype (Letters) Dominant or Phenotype Recessive Trait (Appearanc) Expressed? Homozygous Dominant PP Dominant Purple Homozygous Recessive pp recessive white Heterozygous Pp Dominant Purple flower (dominant), P White flower (recessive), p

Genotype VS Phenotype Freckles (Dominant) Genotype (Words) Genotype (Letters) Dominant or Recessive Trait Expressed? Homozygous Dominant Freckles Recessive Ff No freckles (recessive) Phenotype (Appearance) Fill in missing parts of table

Genotype VS Phenotype Freckles (Dominant) Genotype (Words) Genotype (Letters) Homozygous Dominant FF Homozygous recessive Heterozygous No freckles (recessive) ff Ff Dominant or Recessive Trait Expressed? Dominant Recessive Dominant Fill in missing parts of table Phenotype (Appearance) Freckles No freckles Freckles

Monohybrid Cross X Parents genotype phenotype Pp Purple ? ? White Offspring phenotype genotype 50% purple; 50% white (1: 1 ratio) ? ? or

Monohybrid Cross l l i f u o y n a C ? e h t in X Parents genotype phenotype Pp Purple ? ? White Offspring phenotype genotype 50% purple; 50% white (1: 1 ratio) ? ? or

Monohybrid Cross X Parents genotype phenotype PP Purple ? ? White Offspring phenotype genotype ? ?

Monohybrid Cross l l i X f u o y n a C ? e h t in Parents genotype phenotype PP Purple ? ? White Offspring phenotype genotype ? ?

If X Parents genotype phenotype PP Purple pp White P p gametes

PP X pp 100% Heterozygous Purple White flower’s gametes Purple flower’s gametes P P p Pp Pp

Purple flowers White flowers

Purple flowers White flowers All offspring have purple flowers

P Generation (true-breading parents) Purple flowers White flowers

P Generation (true-breading parents) Purple flowers F 1 Generation White flowers All offspring have purple flowers Fertilization among F 1 plants (F 1 F 1)

P Generation (true-breading parents) Purple flowers F 1 Generation White flowers All offspring have purple flowers Fertilization among F 1 plants (F 1 F 1) F 2 Generation 3 of plants 4 have purple flowers 1 of plants 4 have white flowers

P Generation (true-breading parents) Purple flowers F 1 Generation ? n i a l p x E White flowers All offspring have purple flowers Fertilization among F 1 plants (F 1 F 1) F 2 Generation 3 of plants 4 have purple flowers 1 of plants 4 have white flowers

P Generation Genetic makeup (alleles) Purple flowers Alleles carried PP White flowers pp by parents Gametes All P (sperm or egg) All p

P Generation Genetic makeup (alleles) Purple flowers Alleles carried PP White flowers pp by parents Gametes All P All p F 1 Generation (hybrids) Purple flowers All Pp Gametes 1 P 2 1 p 2

P Generation Genetic makeup (alleles) Purple flowers Alleles carried PP White flowers pp by parents Gametes All p All P F 1 Generation (hybrids) Purple flowers All Pp Alleles segregate Gametes 1 P 2 F 2 Generation (hybrids) Eggs from F 1 plant 1 p 2 Sperm from F 1 plant p P P PP Homozygous dominant (purple) Pp p Punnett Square pp Pp Phenotypic ratio 3 purple : 1 white Heterozygous (purple) Genotypic ratio 1 PP : 2 Pp : 1 pp Homozygous recessive (white)

P Generation Genetic makeup (alleles) Purple flowers Alleles carried PP White flowers pp by parents Gametes All p All P F 1 Generation (hybrids) Purple flowers All Pp Alleles segregate Gametes 1 P 2 F 2 Generation (hybrids) Eggs from F 1 plant 1 p 2 Sperm from F 1 plant p P P p PP Pp Pp pp Phenotypic ratio 3 purple : 1 white Genotypic ratio 1 PP : 2 Pp : 1 pp

P Generation Genetic makeup (alleles) Purple flowers Alleles carried PP White flowers pp by parents Gametes All p All P F 1 Generation (hybrids) Purple flowers All Pp Alleles segregate Gametes 1 P 2 F 2 Generation (hybrids) Eggs from F 1 plant 1 p 2 Sperm from F 1 plant p P P p PP Pp Pp pp Phenotypic ratio 3 purple : 1 white Genotypic ratio 1 PP : 2 Pp : 1 pp Heterozygous (purple) Homozygous dominant (purple) Homozygous recessive (white)

Another Monohybrid Cross Parents Hearing Dd Sperm gametes d D Sperm D Egg gametes Offspring Eggs d DD Hearing Dd Hearing (carrier) Do the Punnett Square Dd Hearing (carrier) dd Deaf

Another Monohybrid Cross Parents Hearing Dd D Offspring D Hearing Dd Sperm d DD Hearing Dd Hearing (carrier) dd Deaf Eggs d

Go to the Study Area in Mastering Biology (masteringbiology. com), Chapter 9 Perform the Monohybrid Cross Activity

Dihybrid Cross Genotype VS Phenotype Texture/Shape: Round/Smooth, R (Dominant) Wrinkled, r (recessive) Color: Yellow, Y (Dominant) green, y (recessive) • Look at two traits together • More gamete variety • More offspring variety • Larger Punnett Square

Dihybrid Cross Genotype VS Phenotype Look at both traits together: Round, Yellow Round, green wrinkled, Yellow wrinkled, green Round, Yellow: R/-Y/Round, green: R/-yy wrinkled, Yellow: rr. Y/wrinkled, green: rryy

Dihybrid Cross Genotype VS Phenotype Genotype (Letters) Phenotype (Appearance) Rr. Yy Round, Yellow RRYY Round, Yellow Rryy Round, green rryy wrinkled, green rr. Yy wrinkled, Yellow rr. YY wrinkled, Yellow

Round-yellow seeds (RRYY) r y Y Y Wrinkled-green seeds (rryy) R R y MEIOSIS r FERTILIZATION Gametes y R Y r All round-yellow seeds (Rr. Yy) Offspring are? R r Y y

Round-yellow seeds (RRYY) r y Y Y Wrinkled-green seeds (rryy) R R y MEIOSIS r FERTILIZATION Gametes y R Y R r y r All round-yellow seeds (Rr. Yy) Rr. Yy

Round-yellow seeds (RRYY) r y Y Y Wrinkled-green seeds (rryy) R R y MEIOSIS r FERTILIZATION Gametes y R Y R r y r All round-yellow seeds (Rr. Yy) Y Rr. Yy Possible gametes? 1 RY 4 1 ry 4 1 r. Y 4 1 Ry 4

Punnett Square (Dihybrid Cross) Rr. Yy x Rr. Yy Gametes from each parent: RY, Ry, r. Y, ry Fill in Punnett Square: Gametes across top and sides; offspring genotypes in middle RY Ry r. Y ry RY RRYy Rr. YY Rr. Yy Ry RRYy RRyy Rr. Yy Rryy r. Y Rr. Yy rr. YY rr. Yy ry Rr. Yy Rryy rr. Yy rryy Phenotypes? How many of each?

Punnett Square (Dihybrid Cross) Rr. Yy x Rr. Yy Gametes from each parent: RY, Ry, r. Y, ry Fill in Punnett Square: Gametes across top and sides; offspring genotypes in middle RY Ry r. Y ry RY Round, Yellow RRYY RRYy Round, Yellow RRYy Round, green RRyy Round, Rr. Yy Yellow Round, Rryy green r. Y Round, Yellow Rr. Yy wrinkled, Yellow rr. YY rr. Yy wrinkled, Yellow ry Round, Yellow Rr. Yy Round, green Rryy wrinkled, Yellow rr. Yy wrinkled, rryy green Round, Rr. YYYellow Rr. Yy Yellow Round, Phenotypes? How many of each? Round, Yellow 9 Round, green 3 wrinkled, Yellow wrinkled, green 3 1

Blind dog Try this one… Phenotypes Black coat, blind (PRA) normal vision B_N_ Genotypes B_nn (a) Possible phenotypes of Labrador retrievers Chocolate coat, normal vision bb. N_ Chocolate coat, blind (PRA) bbnn Mating of double heterozygotes (black coat, normal vision) Bb. Nn Phenotypic ratio of offspring 9 black coat, normal vision (b) A Labrador dihybrid cross Results? 3 black coat, blind (PRA) 3 chocolate coat, normal vision 1 chocolate coat, blind (PRA)

Blind dog Phenotypes Black coat, blind (PRA) normal vision B_N_ Genotypes B_nn (a) Possible phenotypes of Labrador retrievers Blind dog Chocolate coat, normal vision bb. N_ Chocolate coat, blind (PRA) bbnn Mating of double heterozygotes (black coat, normal vision) Bb. Nn Phenotypic ratio of offspring 9 black coat, normal vision (b) A Labrador dihybrid cross Results? 3 black coat, blind (PRA) 3 chocolate coat, normal vision 1 chocolate coat, blind (PRA)

Blind dog Phenotypes Black coat, blind (PRA) normal vision B_N_ Genotypes B_nn (a) Possible phenotypes of Labrador retrievers Blind dog Chocolate coat, normal vision bb. N_ Chocolate coat, blind (PRA) bbnn Mating of double heterozygotes (black coat, normal vision) Bb. Nn Phenotypic ratio of offspring 9 black coat, normal vision (b) A Labrador dihybrid cross 3 black coat, blind (PRA) 3 chocolate coat, normal vision 1 chocolate coat, blind (PRA)

White rr Red RR Gametes What’s going on here? R r Red x White = pink? Sperm R r R Punnett Square RR Rr Eggs r Rr rr

White rr Red RR Gametes What’s going on here? R r Red x White = pink? Pink Rr 1 1 R 2 r 2 Gametes Sperm R r R Punnett Square RR Rr Eggs r Rr rr

White rr Red RR Gametes What’s going on here? R r Red x White = pink? Pink Rr 1 1 R 2 r 2 Gametes Incomplete Dominance Sperm R r Phenotypic Ratio? 1 red: 2 pink: 1 white RR Rr 1: 2: 1 Rr rr R Eggs r

Blood Type Blood Antibodies Reactions When Blood from Type below Is Antigens on Type Genotypes Red Blood Cells Present in Mixed with Antibodies from types at left (Phenotype) Blood A B AB O Antigen A IAIA Anti-B A or IAi Antigen B IBIB B Anti-A or IBi AB O IAIB Antigens A and B present neither ii Neither antigens present Anti-A Anti-B Lab results—what’s your phenotype/genotype?

Blood Type Blood Antibodies When blood from each type below Is Antigens on Type Red Blood Cells Present in donated to blod types at left… (Phenotype) Blood A B AB O Antigen A Anti-B O A, OK A A, OK B A, NOT OK Anti-A O B, OK A B, NOT OK B B, OK AB B, NOT OK AB Antigens A and B present neither O AB, OK A AB, OK B AB, OK AB AB, OK O Neither antigens present Anti-A Anti-B O O, OK A O, NOT OK B O, NOT OK A Antigen B B

Codominance Blood Type Genotypes (Phenotype) A IAIA A allele and B allele both dominant or IAi B IBIB or IBi AB IAIB O ii Allele for neither antigen (O) is recessive

Genetics Practice Try the problems at the end of the chapter.