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Albinism is known to be due to an autoso...

Albinism is known to be due to an autosomal recessive mutation. The first child of a couple with normal skin pigmentation was an albino. What is the probability that their second child will also be an albino?

A

`100%`

B

`25%`

C

`50%`

D

`75%`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem of determining the probability that the second child of a couple, who have a first child that is an albino, will also be an albino, we can follow these steps: ### Step-by-Step Solution: 1. **Understand the Genetics of Albinism**: - Albinism is caused by an autosomal recessive mutation. This means that a person must inherit two copies of the recessive allele (let's denote it as 'a') to express the albino trait. The normal pigmentation allele can be denoted as 'A'. 2. **Determine the Genotypes of the Parents**: - Since the couple has normal skin pigmentation but has an albino child, both parents must be heterozygous (Aa). This means they carry one normal allele (A) and one albino allele (a) but do not express the albino trait themselves. 3. **Set Up a Punnett Square**: - To find the probability of their children being albino, we can set up a Punnett square with the genotypes of the parents: ``` A a ------------ A | AA | Aa | ------------ a | Aa | aa | ------------ ``` - The possible genotypes of the offspring are: - AA (normal pigmentation) - Aa (normal pigmentation, carrier) - Aa (normal pigmentation, carrier) - aa (albino) 4. **Calculate the Probabilities**: - From the Punnett square, we can see the ratios: - 1 AA : 2 Aa : 1 aa - This translates to: - 3 out of 4 (75%) will have normal pigmentation (AA or Aa). - 1 out of 4 (25%) will be albino (aa). 5. **Determine the Probability for the Second Child**: - The probability of the second child being albino is independent of the first child’s genotype. Therefore, the probability remains the same as calculated from the Punnett square. - Thus, the probability that the second child will also be an albino is 25%. ### Final Answer: The probability that their second child will also be an albino is **25%**. ---
To solve the problem of determining the probability that the second child of a couple, who have a first child that is an albino, will also be an albino, we can follow these steps: ### Step-by-Step Solution: 1. **Understand the Genetics of Albinism**: - Albinism is caused by an autosomal recessive mutation. This means that a person must inherit two copies of the recessive allele (let's denote it as 'a') to express the albino trait. The normal pigmentation allele can be denoted as 'A'. 2. **Determine the Genotypes of the Parents**: ...
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