1. Anonychia congenita, an autosomal condition that results in the absence of fi
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Question
1. Anonychia congenita, an autosomal condition that results in the absence of fingernails and toenails, is caused by the recessive allele, 'a.'Alkaptonuria, an inability to metabolize the amino acids phenylalanine and tyrosine, is caused by the autosomal recessive allele, i. If a woman, who exhibits both disorders, marries a normal man whose father exhibited both disorders: Predict the phenotypic ratios of the progeny that would result from a cross between the man and the woman. Please write the phenotypes. The adjectives: Anonychiic and Alkaptonuric are used to describe individuals with Anonychia and Alkaptonuric, respectively What specific type of cross is represented in "b' above? terminology that describes this cross. a. b. You must use the specific 2. In humans, Trimethylaminuria (TMA), also known as fish order syndrome, is a metabolic disorder in which affected individuals can metabolize trimethylamines to trimethylamine oxide. Individuals who have this disorder build up trimethylamines in the body and smell of fish. TMA results from an allele (t) that is recessive to the allele for normal metabolism (T). Sally has normal metabolism but her brother has TMA. Sally's father also has TMA, but her mother has normal metabolism. Give the genotypes of: a. Sally b. Sally's mother c. Sally's father d. Sally's brother.Explanation / Answer
Ans.1. As both Anonychia congenita and Alkaptonuria are Autosomal recessive disorder so the phenotype of the woman which exibhits both the disorders will be "aaii" ( as allele for Anonychia congenita is 'a' and allele for Alkaptonuria is 'i'). Woman will be homozygous for both the alleles as she exibhits both the disorders (autosomal recessive).
Phenotype for the man will be "AaIi" that is man will be heterozygous for the disorders. ( because man's fathers does have the disorder).
So the cross will be between "AaIi" × "aaii"
So cross will yield 4 types of genotypes (AaIi , Aaii , aaIi & aaii)
Phenotype for AaIi will be the person with not any of the two disorders.
Phenotype for Aaii will be the person which is affected by Alkaptonuria but does not have Anonychia congenita.
Phenotype for aaIi will be the person which is affected by Anonychia congenita but does not have Alkaptonuria.
Phenotype for aaii will be the person which is affected by both Alkaptonuria and Anonychia congenita.
Phenotypic ratio would be
AaIi : Aaii : aaIi : aaii
4 : 4 : 4 : 4
that is 1 : 1 : 1 : 1
Ans.2 Phenotype of sally's family will be
a. Sally = Tt
b. Sally's mother = Tt
c. Sally's father = tt
d. Sally's brother = tt
Both sally's brother and father would have genotype of tt beacause they are affected and in case of revessive disorder person genotype will be homozygous.
Both sally and her mother have genotype as Tt because if her mother does not have one recessive allele for TMA then none of the child will be affected by TMA (which is not there is this case as sally's brother is affected)
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