Question

Резус-фактор еритроцитів людини контролюється трьома генами ( СDЕ ). Вони розташовані в одній хромо­сомі на близькій відстані один від другого й успадкову­ються зчеплено. Домінантні гени СDЕ визначають наявність резус-фактора (антигенів С,D,Е) в еритроцитах (резус-позитивна кров), а рецесивні алелі їх - відсутність їх (резус-антиген не виявляється). Наявність резус-фактору (Rh+) визначаються одним домінант­ ним геном D, а вітсутність резус-негативні ( Rh-) - його рецесивним алелем d. Які генотипи і фенотипи будуть у дітей, якщо: а) мати і батько гомозиготні та резус-позитивні; б) ма­ти гомозиготна і резус-позитивна, батько резус-негатив­ ний; в) мати гомозиготна резус-позитивна, батько гете­розиготний і резус-позитивний; г) мати гетерозиготна і резус-позитивна, батько гомозиготний і резус-позитив­ ний; д) батьки гетерозиготні та резус-позитивні; е) мати гетерозиготна і резус-позитивна, батько резус-негатив­ ний; е) мати резус-негативна, батько гетерозиготний і резус-позитивний; ж) батьки резус-негативні?

Answer 1

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Answer 2

Rhesus Factor Inheritance

The inheritance of the Rhesus factor in humans is controlled by three genes (C, D, and E) located on a single chromosome in close proximity to each other and inherited in linkage. The dominant genes C, D, and E determine the presence of the Rhesus factor antigens (C, D, E) in erythrocytes (Rhesus-positive blood), while their recessive alleles determine their absence (Rhesus antigen not detected).

The presence of the Rhesus factor (Rh+) is determined by a single dominant gene D, while the absence of the Rhesus factor (Rh-) is determined by its recessive allele d.

Genotypes and Phenotypes of Offspring

a) If both parents are homozygous and Rhesus-positive: - Genotypes: Both parents have the genotype DD. - Phenotypes: Both parents have Rhesus-positive blood. - Offspring: All offspring will be Rhesus-positive.

b) If the mother is homozygous and Rhesus-positive, and the father is Rhesus-negative: - Genotypes: Mother has the genotype DD, and father has the genotype dd. - Phenotypes: Mother is Rhesus-positive, and father is Rhesus-negative. - Offspring: All offspring will be Rhesus-positive carriers (heterozygous).

c) If the mother is homozygous and Rhesus-positive, and the father is heterozygous and Rhesus-positive: - Genotypes: Mother has the genotype DD, and father has the genotype Dd. - Phenotypes: Mother is Rhesus-positive, and father is Rhesus-positive. - Offspring: There is a 50% chance of Rhesus-positive offspring and a 50% chance of Rhesus-positive carriers (heterozygous) offspring.

d) If the mother is heterozygous and Rhesus-positive, and the father is homozygous and Rhesus-positive: - Genotypes: Mother has the genotype Dd, and father has the genotype DD. - Phenotypes: Mother is Rhesus-positive, and father is Rhesus-positive. - Offspring: There is a 50% chance of Rhesus-positive offspring and a 50% chance of Rhesus-positive carriers (heterozygous) offspring.

e) If both parents are heterozygous and Rhesus-positive: - Genotypes: Both parents have the genotype Dd. - Phenotypes: Both parents are Rhesus-positive. - Offspring: There is a 25% chance of Rhesus-positive offspring, a 50% chance of Rhesus-positive carriers (heterozygous) offspring, and a 25% chance of Rhesus-negative offspring.

f) If the mother is heterozygous and Rhesus-positive, and the father is Rhesus-negative: - Genotypes: Mother has the genotype Dd, and father has the genotype dd. - Phenotypes: Mother is Rhesus-positive, and father is Rhesus-negative. - Offspring: There is a 50% chance of Rhesus-positive carriers (heterozygous) offspring and a 50% chance of Rhesus-negative offspring.

g) If both parents are Rhesus-negative: - Genotypes: Both parents have the genotype dd. - Phenotypes: Both parents are Rhesus-negative. - Offspring: All offspring will be Rhesus-negative.

In summary, the inheritance of the Rhesus factor follows Mendelian genetics, and the genotypes and phenotypes of offspring can be predicted based on the genotypes of the parents and the inheritance patterns of the Rhesus factor genes.