Low platelet count it a recessively inherited trait Reevalua

Low platelet count it a recessively inherited trait. Reevaluation of the genetic screen indicates that Nikoleta is homozygous dominant normal for a trait that causes low platelet count and her husband is homozygous recessive If the F, offspring has normal platelets and beta-thalassemia. What are the parental gametes? Based on the F_1 progeny phenotype given and the parental gametes, write the two possible genotypes. What is the gamete frequency it the two genotypes in (b) were crossed with each other? What is the phenotype frequency for the cross in (c)? Use the evidence from the case to advice Nikoleta and her husband about having a family. Nikoleta and her husband Andrew conceived four times. What are the possible combinations for a boy and get for each time Mrs. Stamos became pregnant?

Solution

Legends-

XX-female

XY-male

HH/hh-homozygous trait for platelets count

Hh-heterozygous trait for platelets count

1.a. The parental gametes will be –

X^HX^H - homozygous dominant mother

X^hY- homozygous recessive

b. possible genotype are- 2X^HX^h and 2X^HY

c. gamete frequency for X^HX^h will be 2/4=1/2

    gamete frequency for X^HY will be 2/4=1/2

d. phenotype frequency is as follows

Parents              Homozygous dominant mother                     Homozygous recessive father

             X^HX^H                                                                      X^hY

                                                                                                                       

Gametes                          X^H                  X^H                                                                              X^h            Y

Male/female

X^H

X^H

X^h

X^HX^h

^{heterozygous dominant}

X^HX^h

^{heterozygous dominant}

Y

X^HY

^{heterozygous dominant}

X^HY

^{heterozygous dominant}

F1 progeny

2. From the f1 progeny it is clear that all offspring are heterozygous, as platelets count is homozygous recessive trait. All children will be normal.

Male/female	XH	XH
Xh	XHXh heterozygous dominant	XHXh heterozygous dominant
Y	XHY heterozygous dominant	XHY heterozygous dominant