Question

4. Assume that the trait in the accompanying pedigree is due to simple Mendelian inheritance. . Co to odno a) Is it likely to be due to a dominant allele or a recessive allele? Explain. b) What is the biological relationship between Ill1 and 1112 c) If the allele responsible for the condition is rare, what are the most likely genotypes of all the people in the pedigree in generations I, II and III? (Use A and a for the dominant and recessive alleles, respectively.)

Answer 1

Dominant trait -- it is expressed when it is either in Homozygous or heterozygous condition.

Example -- here trait is represented by A and a. If dominant can be AA and Aa.

Recessive trait -- it is expressed only in Homozygous condition.

Example -- aa.

Ans a) the trait expressed in the Pedigree is recessive because the parents of individual IV-4 are unaffected with the trait. As parents are unaffected so they can be Homozygous dominant( AA) or heterozygous dominant (Aa). If either of parent is Homozygous dominant so they can't have an affected child. That means IV-4 individual parents are heterozygous dominant (Aa). The trait is recessive as parents aren't affected but are carrier of the recessive allele.

Ans b) the relationship between III-1 and III-2 is that they both have a common ancestor. The II-2 and II-3 are the children or progeny of I-1 and I-2. And I-1 and I-2 are the common ancestor of III-1 and III-2.

Ans c) the genotypes of all the individuals in the Pedigree are as follows:

As the trait is recessive in nature; recessive allele=a and dominant allele=A. Individual with recessive trait=aa; dominant trait = AA or Aa.

The likely genotypes of all individuals are in the image below :

Aa Aa Aa Aa A aa A It can be A A or Aą. НОМСуция gous AIMu dominant or heterozygous dominant (Aa) - π 1 and 0-2 will be Aan because when both parents are heterozygous then only its progeny can have affected child I in recessive condition. - As 11 and 1-2 are Aa, then their parents must be Aabecause they are unaffected and generation several trait. show recessive 20, D1, 12, 13 and Du will be Aa. - Again 12 and 13 are unaffected and their parents too are unaffee spected then will have Aa. Because on haring AA or AA and Aa will not produce affected individual in several generton must beveral generando u

Generation I,II and III will have genotype Aa. IV have aa, A_. _ can be A or a.

Thank you...

Expect a ???....

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