I am having a lot of problems with this question. Please explain how to get the

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I am having a lot of problems with this question. Please explain how to get the answer thoroughly so that I can understand it.

F phenotyic class dunce male dunce female F2 phenotypic class dunce female dunce male dunce, shaggy male shaggy male wt female wt male 425 428 613 312 309 104 205 What is the mode of inheritance for the genes controlling dunce and shaggy? autosomal dominant for dunce and X-linked recessive for shaggy X-linked dominant for dunce and X-linked recessive for shaggy autosomal recessive for dunce and autosomal recessive for shaggy autosomal dominant for dunce and X-linked dominant for shaggy Continued belo What is the genotype of the original male parent? hemizygous mutant at both loci hetrozygous mutant at one locus and hemizygous mutant at the other locus homozygous mutant at both loci homozygous mutant at one locus and O hemizygous mutant at the other locus Previous Give Up& View SolutionCheck Answer Next Hint

Explanation / Answer

For determination of any trait which is autosomal or sex linked we have to focus on their transmission from parents to offsprings.

Autosomal alleles: these alleles are transferred from both parents to any offsprings. These autosomal alleles doesn't have any relation with sexes.

sex linked characters: sex linked characters are associated with sex chromosomes either X chromosome or Y chromosome.

When character is associated with X chromosome: If it is dominant than appears in male and female both in heterozygous condition as well as homozygous condition. When X linked character is recessive than appears in male in all conditions and appears in female only when present in homozygous condition (means two XX ).

Here parental phenotype is given and phenotype of offsprings which are produced by the cross between these parents are given. we have to focus the phenotypes of parents and offsprings and then need to determine the genotype of both.

have you observed that dunce character is appearing in both. but parents are also able to produce wild type offsprngs. means we can say that both parents are heterozygous and they have to different allele one is normal and other is dunes. But the normal alleles are not expressed in parents means we can say that normal allele is recessive over dunes allele. Hence it is concluded that dunes allele is dominant. in the presence of dunes allele, wild-type recessive allele is not able to express their phenotype.

In the case of shaggy phenotype: it is observed that parent doesn't have shaggy phenotype but they are able to produce two kind of offsprings which have Shaggy phenotype as well as normal phenotype. Due to these results we can say that parent have both alleles which is responsible for saggy phenotype and normal file type phenotype. But parents are not able to express Shaggy phenotype. means we can say they have allele for shaggy phenotype but it was present in recessive condition.

So the genotype of parent have: wild alleles and also have allele for dunes and shaggy. But dunes is in dominant condition that is why it is expressed in parents and Shaggy is in recessive condition that is why not expressed in parents.

Dunes character is associated with dominant allele that is why transferred from male to male and female offsprings and female to male and female offsprings.

But shaggy is associated with X chromosome and homozygous recessive condition. Female parent have heterozygous recessive Shaggy allele associated with one X chromosome and another X chromosome of female parent have normal allele.

female parent transfer there Shaggy allele to both male and female offsprings but male offsprings have one x chromosome that is why they Expressed there phenotype. and female parent have to X chromosome that is why not able to express Shaggy phenotype.

Question first: option first is correct. as I mentioned the detail about option first is correct. Dunes is autosomal dominant and Shaggy is recessive with X linked.

Question second: male parent have heterozygous allele for dunes character.

hemizygoys for Shaggy.

these two questions are solved by the knowledge of transmission of characters on autosomal and sex linked formed.

recessive: appears only in homozygous condition.

Dominant : only need 1 allele for expression. can appear in homozygous as well as in heterozygous condition.

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