Question

У человека локус резус-фактора сцеплен с локусом, определяющим форму эритроцитов, и находится от него на расстоянии 3 единиц кроссинговера. Резус-положительность и эллиптоцитоз (эллиптическая форма эритроцитов) определяются доминантными аутосомными генами. Один из супругов гетерозиготен по обоим признакам, причем резус-положительность он унаследовал от одного родителя, эллиптоцитоз – от другого. Второй супруг резус-отрицателен и его эритроциты нормальной формы. Какие дети и с какой вероятностью могут родиться в этой семье?

Answer 1

А-резус положителен, а- резус отрицательный,В- эллиптоцитоз, в- норма.

Р            А//а            а//в 

              в//В            а//в

G  А/   а/   А/   а/      а/

     в/ , В/,  В/, в/      в/

F1     48,5 %  А//а  48,5%  а//а  1,5%  А//а   1,5%  а//а

                        в//а ,              В//в,             В//в,              в//в
        (+,норма)       (-,эллиптоц)  (+,эллиптоц)   (-,норма)

Answer 2

Understanding the Question

The question describes a scenario where a person has a locus of the Rh factor that is linked to a locus determining the shape of red blood cells. The distance between these loci is 3 units of crossing over. Rh positivity and elliptocytosis (elliptical shape of red blood cells) are determined by dominant autosomal genes. One of the spouses is heterozygous for both traits, inheriting Rh positivity from one parent and elliptocytosis from the other. The other spouse is Rh negative and has normal-shaped red blood cells. The question asks about the possible children and their probabilities in this family.

Analyzing the Information

Based on the information provided, we can determine the genotypes of the parents and use Punnett squares to determine the possible genotypes and phenotypes of the children. Let's analyze the information step by step:

1. The person has a locus of the Rh factor that is linked to a locus determining the shape of red blood cells, with a distance of 3 units of crossing over. This means that these two loci are close together on the same chromosome and are likely to be inherited together.

2. Rh positivity and elliptocytosis are determined by dominant autosomal genes. This means that if a person has at least one dominant allele for either trait, they will express the corresponding phenotype.

3. One of the spouses is heterozygous for both traits. This means that they have one dominant allele for Rh positivity and one dominant allele for elliptocytosis.

4. The other spouse is Rh negative and has normal-shaped red blood cells. This means that they do not have any dominant alleles for Rh positivity or elliptocytosis.

Determining the Possible Children

To determine the possible children and their probabilities, we can create a Punnett square for each trait separately.

# Rh Factor:

The Rh factor is determined by a single gene with two alleles: Rh positive (Rh+) and Rh negative (Rh-). The heterozygous spouse is Rh+ (heterozygous genotype: Rh+/Rh-), while the other spouse is Rh- (homozygous genotype: Rh-/Rh-).

| | Rh+ | Rh- | |----------|-----------|-----------| | Rh+ | Rh+/Rh+ | Rh+/Rh- | | Rh- | Rh+/Rh- | Rh-/Rh- |

From the Punnett square, we can see that there is a 50% chance for each child to be Rh+ and a 50% chance to be Rh-.

# Red Blood Cell Shape (Elliptocytosis):

Elliptocytosis is determined by a single gene with two alleles: elliptocytosis (E) and normal shape (e). The heterozygous spouse has elliptocytosis (heterozygous genotype: E/e), while the other spouse has normal-shaped red blood cells (homozygous genotype: e/e).

| | E | e | |----------|-----------|-----------| | E | E/E | E/e | | e | E/e | e/e |

From the Punnett square, we can see that there is a 50% chance for each child to have elliptocytosis and a 50% chance to have normal-shaped red blood cells.

Combining the Results

To determine the possible combinations of the two traits, we can combine the results from the Punnett squares for the Rh factor and red blood cell shape.

| | Rh+ | Rh- | |----------|-----------|-----------| | E | Rh+/E | Rh-/E | | e | Rh+/e | Rh-/e |

From the combined Punnett square, we can see that there are four possible combinations of the two traits:

1. Rh+/E 2. Rh-/E 3. Rh+/e 4. Rh-/e

Conclusion

In this family, the possible children and their probabilities are as follows:

1. Rh+/E: 25% probability 2. Rh-/E: 25% probability 3. Rh+/e: 25% probability 4. Rh-/e: 25% probability

Each child has an equal probability of 25% to have any of the four combinations of the Rh factor and red blood cell shape.

Please note that the probabilities provided assume that the inheritance of the two traits is independent and that there are no other genetic factors involved.

Remember, genetics can be complex, and this analysis is based on the information provided. For a more accurate assessment, it is recommended to consult with a genetic counselor or healthcare professional.