Assuming diallelic genes, that express complete dominance, and assort independently, <em>1) </em><em>Genotypic ratio</em><em>=1:2:1. </em><em>Phenotypic ratio</em><em>=3:1 </em><em>/</em><em> 2) </em><em>Parental genotype</em><em>: PpRr. </em><em>Gametes</em><em>= PR, Pr, pR, pr. </em><em>Phenotypic ratio</em><em>: 9:3:3:1</em>
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We will assume diallelic genes that express complete dominance. In cases where two or more genes are involved, we will assume they are not linked, and alleles assort independently.
1) <u>FRECKLES</u>
- F is the dominant allele that codes for freckles
- f is the recessive allele that codes for no-freckles
Cross: Between a mother and a father who both have freckles and are heter0zyg0us for the trait
Parentals) Ff x Ff
Gametes) F f F f
Punnett square) F f
F FF Ff
f Ff ff
F1) Genotype
- 1/4 = 25% of the progeny is expected to be h0m0zyg0us dominant, FF
- 2/4 = 1/2 = 50% of the progeny is expected to be heter0zyg0us, Ff
- 1/4 = 25% of the progeny is expected to be h0m0zyg0us recessive, ff
Phenotype
- 3/4 = 75% of the progeny is expected to express freckles, FF + Ff
- 1/4 = 25% of the progeny is expected to not express freckles, ff
Genotypic ratio ⇒ 1:2:1
Phenotypic ratio ⇒ 3:1
2) <u>FLOWER COLOR AND SEED SHAPE</u>
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- P is the dominant allele that codes for purple flowers
- p is the recessive allele that codes for white flowers
- R is the dominant allele that codes for round seeds
- r is the recessive allele that codes for wrinkled seeds
Cross: Between two plants that are heter0zyg0us for flower color and seed shape
Parentals) PpRr x PpRr
Gametes) PR, Pr, pR, pr PR, Pr, pR, pr
Punnett square) PR Pr pR pr
PR PPRR PPRr PpRR PpRr
Pr PPRr PPrr PpRr Pprr
pR PpRR PpRr ppRR ppRr
pr PpRr Pprr ppRr pprr
F1) Genotype
- 1/16 individuals are expected to be PPRR
- 2/16 individuals are expected to be PPRr
- 1/16 individuals are expected to be PPrr
- 2/16 individuals are expected to be PpRR
- 4/16 individuals are expected to be PpRr
- 2/16 individuals are expected to be Pprr
- 1/16 individuals are expected to be ppRR
- 2/16 individuals are expected to be ppRr
- 1/16 individuals are expected to be pprr
Phenotype
- 9/16 individuals are expected to have purple flowers with round seeds, PPRR + PpRR + PPRr + PpRr
- 3/16 individuals are expected to have purple flowers and wrinckled seeds, PPrr + Pprr
- 3/16 individuals are expected to have white flowers and round seeds, ppRR + ppRr
- 1/16 individuals are expeceted to have white flowers and wrinckled seeds, pprr.
Phenotypic ratio ⇒ 9:3:3:1
Genotype of parent plant 1: PpRr
- Gamete 1: PR
- Gamete 2: Pr
- Gamete 3: pR
- Gamete 4: pr
Genotype of parent plant 2: PpRr
- Gamete 1: PR
- Gamete 2: Pr
- Gamete 3: pR
- Gamete 4: pr
<u> PHENOTYPE GENOTYPE </u>
purple flowers, round seeds: PPRR, PpRR, PPRr, PpRr
purple flowers, wrinkled seeds: PPrr, Pprr
white flowers, round seeds: ppRR, ppRr
<u>white flowers, wrinkled seeds: pprr </u>
<u> PHENOTYPE NUMBER </u>
purple flowers, round seeds: 9
purple flowers, wrinkled seeds: 3
white flowers, round seeds: 3
<u>white flowers, wrinkled seeds: 1 </u>
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You can learn more about monohybrid and dihybrid crosses at
brainly.com/question/1185199?referrer=searchResults
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