Question

У человека наличие в эритроцитах антигена резус-фактор (фенотип Rh) определяется доминантным геном D. Его аллель d обусловливает отсутствие этого антигена (фенотип Rh).Мужчина с резус-отрицательной кровью IV группы женился на женщине с резус-положительной кровью III группы. У отца жены была резус-отрицательная кровь I группы. В семье имеется два ребёнка: первый - с резус-отрицательной кровью III группы, второй - с резус-положительной кровью I группы. Судебно-медицинская экспертиза установила, что один из этих детей - внебрачные. По какой из двух пар аллелей исключается отцовство?

Answer 1

Решение во вложении:                           

Answer 2

Understanding the Question

The question is asking which pair of alleles can be excluded as the father's alleles based on the given information about the blood types and Rh factor of the individuals involved.

Background Information

The Rh factor is a protein found on the surface of red blood cells. It is determined by the presence or absence of the Rh antigen. The Rh antigen is encoded by the RHD gene, and the absence of the Rh antigen is determined by the presence of the d allele of the RHD gene.

In this case, the man has Rh-negative blood (lacks the Rh antigen) and is of blood type IV. The woman has Rh-positive blood (has the Rh antigen) and is of blood type III. The woman's father has Rh-negative blood and is of blood type I. The couple has two children: one with Rh-negative blood and blood type III, and the other with Rh-positive blood and blood type I. It has been determined through forensic examination that one of these children is illegitimate.

Determining the Possible Allele Combinations

To determine which pair of alleles can be excluded as the father's alleles, we need to consider the possible combinations of alleles for the parents and the children.

The man is Rh-negative, which means he has at least one d allele. Since the d allele is recessive, he could have either two d alleles (dd) or one d allele and one D allele (Dd).

The woman is Rh-positive, which means she must have two D alleles (DD or Dd).

The woman's father is Rh-negative, which means he must have at least one d allele. Since the woman is Rh-positive, her father must have one d allele and one D allele (Dd).

Now let's consider the possible allele combinations for the children:

1. The first child has Rh-negative blood and blood type III. This means the child must have at least one d allele. Since the mother is Rh-positive, the child must have inherited the d allele from the father. Therefore, the first child's genotype is dd.

2. The second child has Rh-positive blood and blood type I. This means the child must have at least one D allele. Since the mother is Rh-positive, the child must have inherited the D allele from the mother. Therefore, the second child's genotype is Dd or DD.

Based on this information, we can conclude that the pair of alleles that can be excluded as the father's alleles is DD.

Conclusion

The pair of alleles that can be excluded as the father's alleles is DD. The possible allele combinations for the father are dd or Dd.

Please note that this conclusion is based on the information provided in the question and the assumptions made about the inheritance of blood types and the Rh factor. It is always recommended to consult with a medical professional or genetic counselor for a definitive answer in specific cases.