 Key Terms: › Hybrid – Heterozygous Organism – Ff › Purebred  Homozygous Dominant - FF  Homozygous Recessive – ff › P Generation – Refers to the parent generation › F 1 – First Generation (first set of offspring) › F 2 – Second Generation (second set of offspring

 Mendel, the father of genetics, completed over 100 experiments examining inheritance patters (traits) in pea plants  Today, instead of repeating all of his experiments, we can use Punnett Squares to predict the traits the offspring will inherit

 Monohybrid Cross only studies on trait

 Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › P 1 : RR x rr R r R r

 Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › P 1 : RR x rr Rr R r R r

 Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › P 1 : RR x rr Rr R r R r

 Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › P 1 : RR x rr Rr R r R r

 Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › P 1 : RR x rr  F 1 Genotype: › Homozygous Dominant = › Heterozygous = › Homozygous Recessive =  F 1 Phenotype: › Round = › Wrinkled = Rr R r R r

 Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › P 1 : RR x rr  F 1 Genotype: › Homozygous Dominant = 0% › Heterozygous = 4 Rr, 100% › Homozygous Recessive = 0%  F 1 Phenotype: › Round = 4, 100% › Wrinkled = 0% Rr R r R r

 Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › F 1 : Rr x Rr r R R r

 Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › F 1 : Rr x Rr RR r R R r

 Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › F 1 : Rr x Rr RRRr r R R r

 Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › F 1 : Rr x Rr RRRr r R R r

 Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › F 1 : Rr x Rr  F 2 Genotype: › Homozygous Dominant = › Heterozygous = › Homozygous Recessive =  F 2 Phenotype: › Round = › Wrinkled = RRRr rr r R R r

 Trait: Seed Shape › Round – Dominant › Wrinkle – Recessive › F 1 : Rr x Rr  F 2 Genotype: › Homozygous Dominant = 1 RR, 25% › Heterozygous = 2 Rr, 50% › Homozygous Recessive = 1 rr, 25%  F 2 Phenotype: › Round = 3, 75% › Wrinkled = 1, 25% RRRr rr r R R r

 Trait: Seed Color › Yellow – Dominant › Green – Recessive › Cross a Homozygous Dominant with a Heterozygous Yellow › ? x ?

 Trait: Seed Color › Yellow – Dominant › Green – Recessive › Cross a Homozygous Dominant with a Heterozygous Yellow › YY x Yy

 Trait: Seed Color › Yellow – Dominant › Green – Recessive › Cross a Homozygous Dominant with a Heterozygous Yellow › YY x Yy Y

 Trait: Seed Color › Yellow – Dominant › Green – Recessive › Cross a Homozygous Dominant with a Heterozygous Yellow › YY x Yy YY

 Trait: Seed Color › Yellow – Dominant › Green – Recessive › Cross a Homozygous Dominant with a Heterozygous Yellow › YY x Yy Y Y Y

 Trait: Seed Color › Yellow – Dominant › Green – Recessive › Cross a Homozygous Dominant with a Heterozygous Yellow › YY x Yy Y Y Y y

 Trait: Seed Color › Yellow – Dominant › Green – Recessive › Cross a Homozygous Dominant with a Heterozygous Yellow › YY x Yy YY Y Y Y y

 Trait: Seed Color › Yellow – Dominant › Green – Recessive › Cross a Homozygous Dominant with a Heterozygous Yellow › YY x Yy YY Y Y Y y

 Trait: Seed Color › Yellow – Dominant › Green – Recessive › Cross a Homozygous Dominant with a Heterozygous Yellow › YY x Yy YY Yy Y Y Y y

 Trait: Seed Color › Yellow – Dominant › Green – Recessive › YY x Yy  Genotype: › Homozygous Dominant = › Heterozygous = › Homozygous Recessive =  Phenotype: › Yellow = › Green = YY Yy Y Y Y y

 Trait: Seed Shape › Yellow – Dominant › Green – Recessive › YY x Yy  Genotype: › Homozygous Dominant = 2 RR, 50% › Heterozygous = 2 Yy, 50% › Homozygous Recessive = 0%  Phenotype: › Yellow = 4, 100% › Green = 0% YY Yy Y Y Y y

 Incomplete dominance or codominance is when 2 alleles are dominant or expresses  Four O’Clock Japanese Flower › Red – Dominant › White – Dominant  RR – Red  WW – White  RW – Pink

 Four O’Clock Japanese Flower › Red – Dominant › White – Dominant  RR – Red  WW – White  RW – Pink › RR x WW  Genotypes: R W R W

 Four O’Clock Japanese Flower › Red – Dominant › White – Dominant  RR – Red  WW – White  RW – Pink › RR x WW  Genotypes: RW R W R W

 Four O’Clock Japanese Flower › Red – Dominant › White – Dominant  RR – Red  WW – White  RW – Pink › RR x WW  Genotypes: › RW = Pink, 100% RW R W R W

 Color of Mice › White – Dominant › Black – Dominant  WW – White  BB – Black  WB – Grey › BB x WB  Genotypes: B W B B

 Color of Mice › White – Dominant › Black – Dominant  WW – White  BB – Black  WB – Grey › BB x WB  Genotypes: BW BB B W B B

 Color of Mice › White – Dominant › Black – Dominant  WW – White  BB – Black  WB – Grey › BB x WB  Genotypes: › BB = Black, 50% › WB = Grey, 50% BW BB B W B B

 Polygenic Traits are traits that are controlled by two or more different genes › Example:  Eye Color  Skin Color

 Multiple Alleles for one trait › Example: Blood Type Blood TypeGenotype AI A I A or I A i O BI B I B or I B i O ABIAIBIAIB OiOiOiOiO

 Blood Type › Cross:  I A I A x I B I B  Genotypes: IAIA IAIA IBIB IBIB

 Blood Type › Cross:  I A I A x I B I B  Genotypes: IAIBIAIB IAIBIAIB IAIBIAIB IAIBIAIB IAIA IAIA IBIB IBIB

 Blood Type › Cross:  I A I A x I B I B  Genotypes: › I A I B = AB, 100% IAIBIAIB IAIBIAIB IAIBIAIB IAIBIAIB IAIA IAIA IBIB IBIB

 Blood Type › Cross:  I A i O x I B i O  Genotypes: IAIA iOiO IBIB iOiO

 Blood Type › Cross:  I A i O x I B i O  Genotypes: IAIBIAIB IBiOIBiO IAiOIAiO iOiOiOiO IAIA iOiO IBIB iOiO

 Blood Type › Cross:  I A i O x I B i O  Genotypes: › I A I B = AB, 25% › I A i O = A, 25% › I B i O = B, 25% › i O i O = O, 25% IAIBIAIB IBiOIBiO IAiOIAiO iOiOiOiO IAIA iOiO IBIB iOiO

 Sex Linked Traits are traits coded by the alleles only on the sex chromosomes (X or Y)  In fruit flies, eye color is determined by the alleles found on the X chromosome › Red Eyes – Dominant › White Eyes – Recessive  X R – Dominant Allele  X r – Recessive Allele  Some sex linked traits in humans include color blindness (X C X C or X C Y) and hemophilia (X h X h or X h Y)

GenotypeSex and Eye Color XRYXRYMale; Red Eyes XrYXrYMale; White Eyes X R Female; Red Eyes X R X r Female; Red Eyes X r Female; White Eyes

 Fruit Flies › Cross:  X R Y x X r X r  Genotypes: XRXR Y XrXr XrXr

 Fruit Flies › Cross:  X R Y x X r X r  Genotypes: XRXrXRXr XRXR Y XrXr XrXr

 Fruit Flies › Cross:  X R Y x X r X r  Genotypes: XRXrXRXr XrYXrY XRXR Y XrXr XrXr

 Fruit Flies › Cross:  X R Y x X r X r  Genotypes: XRXrXRXr XrYXrY XRXrXRXr XRXR Y XrXr XrXr

 Fruit Flies › Cross:  X R Y x X r X r  Genotypes: XRXrXRXr XrYXrY XRXrXRXr XrYXrY XRXR Y XrXr XrXr

 Fruit Flies › Cross:  X R Y x X r X r  Genotypes: › X R X r = Female; Red Eyes, 50% › X r Y = Male; White Eyes, 50% XRXrXRXr XrYXrY XRXrXRXr XrYXrY XRXR Y XrXr XrXr

 Dihybrid Crosses study 2 traits on a Punnett Square › This punnett square will have 16 boxes instead of 4

 Plant Height and Seed Shape › Tall = Dominant › Short = Recessive › Round = Dominant › Wrinkled = Recessive  Cross a Tall Round x Short Wrinkled › All Possible combinations of alleles in gamete:  TTRR x ttrr  TR; TR; TR; TR & tr; tr; tr; tr

TR tr

TtRr TR tr Phenotye: 16 Tall and Round, 100%

 Plant Height and Seed Shape › Tall = Dominant › Short = Recessive › Round = Dominant › Wrinkled = Recessive  Cross two heterozygous tall and round: › ? X ? › All Possible combinations of alleles in gamete:  ?

 Plant Height and Seed Shape › Tall = Dominant › Short = Recessive › Round = Dominant › Wrinkled = Recessive  Cross two heterozygous tall and round: › TtRr X TtRr › All Possible combinations of alleles in gamete:  ?

 Plant Height and Seed Shape › Tall = Dominant › Short = Recessive › Round = Dominant › Wrinkled = Recessive  Cross two heterozygous tall and round: › TtRr X TtRr › All Possible combinations of alleles in gamete:  TR; Tr; tR; tr & TR; Tr; tR; tr

TTRRTTRrTtRRTtRr TTRrTTrrTtRrTtrr TtRRTtRrttRRttRr TtRrTtrrttRrttrr TRTrtrtR TR Tr tR tr

 Phenotypes: › 9 Tall and Round – 56% › 3 Tall and Wrinkled – 19% › 3 Short and Round – 19% › 1 Short and Wrinkled – 6%  When you cross 2 heterozygous organisms in a dihybrid cross, you will always have: › 9 of the same phenotype – Dominant/Dominant › 3 of the same phenotype – Dominant/Recessive › 3 of the same phenotype – Recessive/Dominant › 1 of the same phenotype – Recessive/Recessive › 9 : 3 : 3 : 1