A color-blind man marries a phenotypically normal woman whose mother was color-blind. What… — JAMB UTME

A color-blind man marries a phenotypically normal woman whose mother was color-blind. What is the probability that any female child born to this couple will be color-blind?

A
$25\%$
$50\%$ Cevap
C
$75\%$
D
$100\%$

Cevap

The probability that a female child born to this couple will be color-blind is

50\%

The father has the genotype

X^c Y

and passes his

X^c

chromosome to all female children. The mother is phenotypically normal but carries the allele from her color-blind mother, making her genotype

X^C X^c

. Half of her egg cells carry

X^C

and half carry

X^c

. Therefore,

50\%

of female offspring receive

X^c

from both parents (

X^c X^c

) and are color-blind.

Adım Adım Çözüm

Determine the genotypes of the parents.

The father is color-blind (

X^c Y

). The mother is phenotypically normal but her mother was color-blind (

X^c X^c

), meaning the mother must be a carrier (

X^C X^c

Sex-linked recessive traits on the X chromosome require identifying maternal and paternal allele contributions.

Perform a genetic cross for female offspring.

Female children inherit

X^c

from the father and either

X^C

X^c

from the mother, resulting in genotypes

X^C X^c

(carrier) and

X^c X^c

(color-blind) in a

1:1

ratio.

Determining the phenotypic ratio specifically among female offspring requires considering only the XX combinations.

Calculate the probability for female offspring.

1

out of

2

female children (

50\%

) will have the

X^c X^c

genotype and express color blindness.

The question asks specifically for the probability among female children.

Anahtar Kavram

Sex-Linked Inheritance and Female Phenotypic Probability

Soru

Cevap

Adım Adım Çözüm

Anahtar Kavram

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