1
Question
Short / Long answer type questions.
Haemophilia is sex-linked recessive disorder of humans. The pedigree chart given ahead shows the inheritance of haemophilia in one family. Study the pattern of inheritance and answer the questions given.
(a) Give all the possible genotypes of the members 4, 5 and 6 in the pedigree chart,
(b) A blood test shows that the individual 14 is a carrier of hemophiliac. The member numbered 15 has recently married the member numbered 14. What is the probability that their first child will be a haemophiliac male?
Haemophilia is sex-linked recessive disorder of humans. The pedigree chart given ahead shows the inheritance of haemophilia in one family. Study the pattern of inheritance and answer the questions given.
(a) Give all the possible genotypes of the members 4, 5 and 6 in the pedigree chart,
(b) A blood test shows that the individual 14 is a carrier of hemophiliac. The member numbered 15 has recently married the member numbered 14. What is the probability that their first child will be a haemophiliac male?
Open in App
Solution
- Hemophilia is a sex-linked recessive disorder which means that the mutation to cause the disease is placed the X chromosome.
- This disease is usually common in males as they have only one X chromosome in their genotype while for females to have this disease they need to have the homologous genotype for the recessive disease ie 2 X chromosomes with the Hemophilia mutation.
- for the pedigree provided above in the figure, one of the parents has to be the carrier of the disease as none of them are affected with the disease. As this is a sex-linked recessive disorder only the females can be the carrier. Therefore the female ie member 2 in the first generation is the carrier.
- (a) member 4 has the genotype of XX as this female is neither a carrier nor affected by the disease. Member 5 has the genotype of X'Y where X' indicates that the chromosome has hemophilia mutation, this male of the second generation if affected by the disease. Member 6 has the genotype of XY as this male is not affected by the disease.
- (b) Member 14 of the third generation is a female who is the carrier of hemophilia disease who is married to a male who is not affected by the disease, therefore, has the genotype of XY. This concludes that there are 25% chances that their first child can be a male with Hemophilia disease.
- Hemophilia is a sex-linked recessive disorder which means that the mutation to cause the disease is placed the X chromosome.
- This disease is usually common in males as they have only one X chromosome in their genotype while for females to have this disease they need to have the homologous genotype for the recessive disease ie 2 X chromosomes with the Hemophilia mutation.
- for the pedigree provided above in the figure, one of the parents has to be the carrier of the disease as none of them are affected with the disease. As this is a sex-linked recessive disorder only the females can be the carrier. Therefore the female ie member 2 in the first generation is the carrier.
- (a) member 4 has the genotype of XX as this female is neither a carrier nor affected by the disease. Member 5 has the genotype of X'Y where X' indicates that the chromosome has hemophilia mutation, this male of the second generation if affected by the disease. Member 6 has the genotype of XY as this male is not affected by the disease.
- (b) Member 14 of the third generation is a female who is the carrier of hemophilia disease who is married to a male who is not affected by the disease, therefore, has the genotype of XY. This concludes that there are 25% chances that their first child can be a male with Hemophilia disease.
Suggest Corrections
0
Similar questions
