Q.30 The allele associated with albinism in humans is recessive (c). The probability
that an albino male (cc) and a carrier female (Cc) will have an offspring with
normal skin pigmentation is _______ .
(Round off to one decimal place)
Understanding Albinism Genetics: Probability of Normal Pigmentation Offspring
Albinism in humans follows an autosomal recessive inheritance pattern, where the recessive allele (c) causes lack of pigmentation only in homozygous (cc) individuals. An albino male (cc) and carrier female (Cc) produce offspring with a 50% chance of normal skin pigmentation (CC or Cc genotypes). This probability, expressed as a decimal rounded to one decimal place, is 0.5.
Punnett Square Analysis
The cross between cc (male) and Cc (female) yields:
-
Cc (normal pigmentation): 50%
-
cc (albino): 50%
| Male Gametes | C (Female) | c (Female) |
|---|---|---|
| c | Cc | cc |
| c | Cc | cc |
Half the offspring show dominant normal pigmentation.
Option Explanations
No explicit multiple-choice options appear in the query, but common exam variants include:
-
0.3 (30%): Incorrect; underestimates carrier transmission.
-
0.5 (50%): Correct; matches genotypic ratios from the Cc × cc cross.
-
0.7 (70%): Incorrect; confuses with heterozygous × heterozygous (Cc × Cc = 75% normal).
-
1.0 (100%): Incorrect; ignores recessive allele contribution.
This calculation applies directly to autosomal recessive traits like oculocutaneous albinism.
