Question

Задача 48. У человека гемофилия детерминирована сцепленным с Х-хромосомой рецессивным геном. Какова вероятность рождения ребёнка от брака с генотипически здоровым партнёром: а) мужчины, брат которого страдает гемофилией; б) здоровой женщины, имеющей такого брата?

Answer 1

В случае а, если женщина, как сказано, генотипический здорова, то её генотип таков: X(A)X(A)
Она скрещивается с мужчиной, Тоже здоровым: P:X(A)X(A) x X(A)Y- Все дети здоровы.
В случае Б мать может иметь генотип X(A)X(a), если это так,  То мужчнина, генотипеческий здоровый- X(A)Y скрестится с ней, но все девочки в семье будут здоровы, а 50% мальчиков больны. 
P:X(A)X(a) x X(A)Y
F1: X(A)X(A) X(A)Y X(a)Y (последний- больной мальчик)

Answer 2

Task 48: Probability of Offspring with Hemophilia

When a person has hemophilia, which is determined by a recessive gene on the X chromosome, the probability of having a child with a genotypically healthy partner can be calculated in two scenarios:

a) Probability with a male partner who has hemophilia: - In this case, the male partner has hemophilia, which means he has one X chromosome with the hemophilia gene. - The female partner is genotypically healthy, meaning she has two X chromosomes, with neither carrying the hemophilia gene.

The probability of having a son with hemophilia in this scenario can be calculated using the Punnett square method. Since the male partner has hemophilia, he will pass on the affected X chromosome to all his daughters, who will be carriers, but none of his sons will inherit the affected X chromosome. Therefore, the probability of having a son with hemophilia in this scenario is 0%.

b) Probability with a female partner who has a brother with hemophilia: - In this case, the female partner is genotypically healthy, but she has a brother who has hemophilia. This means she is a carrier of the hemophilia gene.

The probability of having a son with hemophilia in this scenario can also be calculated using the Punnett square method. Since the female partner is a carrier, there is a 50% chance that she will pass on the affected X chromosome to her sons, resulting in a 50% probability of having a son with hemophilia.

In summary, the probability of having a son with hemophilia is 0% when the male partner has hemophilia, and 50% when the female partner is a carrier of the hemophilia gene due to having a brother with hemophilia.

I hope this helps! If you have further questions or need clarification, feel free to ask.