2) In humans, earlobes are either \"free\" or \"attached\". The free earlobe tra
ID: 255784 • Letter: 2
Question
2) In humans, earlobes are either "free" or "attached". The free earlobe trait is dominant over attached earlobes. The ability to taste certain substances is also genetically controlled. Some people can taste Phenylthiocarbamate (PTC), a dominant trait, while others cannot (the recessive trait) A man heterozygous for both free earlobes and ability to taste PTC marries a woman with attached earlobes who is heterozygous for the ability to taste PTC. Show all work including a Punnett square below-E-free earlobes, e-attached earlobes; P PTC taster, p-non PTC taster a. What are the genotypes of the parents? Male's genotype: b. What are the possible gametes for each parent? Draw a Punnett square to determine the Female's genotype: genotypes and phenotypes of their children. Lab Exercise 10 c. What is the phenotypic ratio for this cross? Be sure to write out phenotypes.Explanation / Answer
2a. Male parent: Heteozygous for Free earlobes and ability to taste PTC.
There should be one dominant allele and recessive allele of each gene
Hence, the male genotype will be PpEe
Female parent: Attached earlobes, and heterozygous for ability to taste PTC
Attached earlobe is a recessive phenotype. Hence, both alleles for attached earlobe is ee.
Heterozygous for ability to taste PTC has one dominant and one recessive allele.
Hence, female genotype: Ppee
b. Possible gametes for each parent:
Male parent= PE, Pe, pE and pe
Female parent: Pe, pe, Pe, pe (0r just Pe, pe as they are same types of two gametes)
Punnett Square:
Mother
Ppee
Pe
pe
Pe
pe
Father
PpEe
PE
PPEe
Can taste PTC,
Free earlobes
PpEe
Can taste PTC, Free earlobes
PPEe
Can taste PTC,
Free earlobes
PpEe
Can taste PTC, Free earlobes
Pe
PPee
Can taste PTC,
Attached earlobes
Ppee
Can taste PTC,
Attached earlobes
PPee
Can taste PTC,
Attached earlobes
Ppee
Can taste PTC,
Attached earlobes
pE
PpEe
Can Taste PTC,
Free earlobes
ppEe
Non PTC taster
Free earlobes
PpEe
Can Taste PTC,
Free earlobes
ppEe
Non PTC taster
Free earlobes
pe
Ppee
Can taste PTC,
Attached earlobes
Ppee
Non PTC taster
Attached earlobes
Ppee
Can taste PTC,
Attached earlobes
Ppee
Non PTC taster
Attached earlobes
2c. The phenotypic ratio is 8 Can taste PTC with free earlobes: 4 Can taste PTC with attached earlobes: 2 Non PTC taster with free earlobes: 2 Non PTC taster with attached earlobes i.e. 8:4:2:2 (or 4:2:1:1).
Mother
Ppee
Pe
pe
Pe
pe
Father
PpEe
PE
PPEe
Can taste PTC,
Free earlobes
PpEe
Can taste PTC, Free earlobes
PPEe
Can taste PTC,
Free earlobes
PpEe
Can taste PTC, Free earlobes
Pe
PPee
Can taste PTC,
Attached earlobes
Ppee
Can taste PTC,
Attached earlobes
PPee
Can taste PTC,
Attached earlobes
Ppee
Can taste PTC,
Attached earlobes
pE
PpEe
Can Taste PTC,
Free earlobes
ppEe
Non PTC taster
Free earlobes
PpEe
Can Taste PTC,
Free earlobes
ppEe
Non PTC taster
Free earlobes
pe
Ppee
Can taste PTC,
Attached earlobes
Ppee
Non PTC taster
Attached earlobes
Ppee
Can taste PTC,
Attached earlobes
Ppee
Non PTC taster
Attached earlobes
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