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 Inheritance
The question concerns the inheritance of albinism, a condition caused by a recessive allele ($c$). We need to find the probability that an offspring will have normal skin pigmentation when an albino male (genotype $cc$) mates with a carrier female (genotype $Cc$). Normal skin pigmentation requires at least one dominant allele ($C$).
Genetic Cross Analysis
We can determine the possible genotypes of the offspring using the parents' genotypes:
- Male parent genotype: $cc$ (produces only $c$ gametes)
- Female parent genotype: $Cc$ (produces $C$ and $c$ gametes with equal probability)
Punnett Square Method
A Punnett square helps visualize the possible combinations of alleles in the offspring:
| $c$ | $c$ | |
| $C$ | $Cc$ | $Cc$ |
| $c$ | $cc$ | $cc$ |
The possible genotypes for the offspring are $Cc$ and $cc$. The phenotypes are:
- $Cc$: Normal skin pigmentation (inherits one dominant $C$ allele)
- $cc$: Albinism (inherits two recessive $c$ alleles)
Calculating Probability
From the Punnett square, 2 out of the 4 possible offspring genotypes are $Cc$. Therefore, the probability of an offspring having normal skin pigmentation is:
$ P(\text{Normal Pigmentation}) = P(Cc) = \frac{\text{Number of } Cc \text{ outcomes}}{\text{Total number of outcomes}} = \frac{2}{4} = \frac{1}{2} $
Converting the fraction to a decimal:
$ \frac{1}{2} = 0.5 $
The question asks to round the answer to one decimal place. The probability is 0.5.
Important Questions from Mendelian Inheritance
- Mendel's 'law of segregation' applies to the segregation of __________ during gamete formation.
- Fabry disease in humans is a X-linked disease. The probability (in percentage) for a phenotypically normal father and a carrier mother to have a son with Fabry disease is ________.
- The blood group of the mother is A⁺ and that of the father is AB⁺. Which of the following statements is/are correct?
- Assuming independent assortment and no recombination, the number of different combinations of maternal and paternal chromosomes in gametes of an organism with a diploid number of 12 is ________.
In a Mendel's dihybrid experiment, a homozygous pea plant with round yellow seeds was crossed with a homozygous plant with wrinkled green seeds.
F₁ intercross produced 560 F₂ progeny. The number of F₂ progeny having both dominant traits (round and yellow) is ________
