What Are the Possible Genotypes of the Bull and Cows in This Monohybrid Cross?

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Discussion Overview

The discussion revolves around determining the possible genotypes of a bull and three cows in a monohybrid cross, specifically focusing on traits related to horn presence and the inheritance patterns observed in chickens with a specific trait (creepers). The scope includes genetic explanations and reasoning based on observed offspring ratios.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes the inheritance pattern of creepers in chickens, suggesting that the creeper allele may be dominant and proposing that one genotype could be lethal to explain the observed offspring ratios.
  • Another participant proposes designating the creeper allele as C and the normal allele as N, indicating that a creeper could have genotypes CN or CC, while normal birds could be CN or NN.
  • A participant emphasizes the need to identify which trait is dominant and whether the parents are heterozygous or homozygous, reiterating the assumption of a lethal genotype to explain the offspring ratios.
  • There is a correction regarding the expected offspring ratio if the creeper trait is dominant, noting that a 3:1 ratio would be expected instead of the 2:1 ratio mentioned.
  • A participant expresses regret for a previous statement made in a moment of fatigue, indicating a potential misunderstanding or error in reasoning.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the dominant trait or the genotypes of the parents, with multiple competing views and assumptions about the genetic mechanisms involved in the crosses.

Contextual Notes

Participants rely on assumptions about lethality and dominance without resolving the implications of these assumptions on the genotypes of the bull and cows. The discussion includes varying interpretations of the genetic ratios observed.

Karma
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Chickens with shortened wings and legs are called creepers, when creepers are mated to normal birds, they produce half creepers and half normal birds. When creepers aremated to creepers they produce 2 creepers to 1 normal. Crosses between normal birds produce only normal offspring. How must thesee results be explained?



Determine the geotypes of the bull and the 3 cwos. Hornless is recessive when Cow A is mated with the bull, the calves are all hornless. When cow B is mated with the bull the calvbes are all hornless. When cow C is mated with the bull a horned calf results. Cow A is horned. Cow B is hornless and Cow C is hornless



Thanks any help will be appreciated
 
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It is difficult to give hint without answering the question but here goes:

Call the creeper allel C and the normal one N, then a creeper may have genotype CN or CC, normal ones could be CN or NN. See what genoptypes the offspring would have assuming the different possible genotypes of the parents (you will have to assume that one genotype is letal in order to explain the "2 creeper 1 normal" frequency of the offspring of creepers corssed with creepers).


Call hornless allel H and the horns allel N, since hornless is recessive you know that all hornless cows must have genotype HH, using the results of the crossings you can easily figure out whether the others are HN or NN.
 
Karma, first figure out which trait is dominant and if the parent are heterozygous or homozygous


gerben said:
(you will have to assume that one genotype is letal in order to explain the "2 creeper 1 normal" frequency of the offspring of creepers corssed with creepers).

No you don't. Creeper is probably dominant and the parent are probably heterozygous
 
iansmith said:
No you don't. Creeper is probably dominant and the parent are probably heterozygous

but then you would get 3 creeper 1 normal (not 2:1)
 
My bad. Maybe I should avoid answering question right after I wake up.
 

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