Determining Gamete Combinations with Independent Assortment
The number of different combinations of chromosomes in gametes is determined by the haploid number of chromosomes in an organism, assuming independent assortment.
Understanding Diploid and Haploid Numbers
- The diploid number ($2n$) represents the total number of chromosomes in somatic cells.
- The haploid number ($n$) represents half the diploid number, found in gametes.
Calculating Haploid Number
Given the diploid number ($2n$) is 12:
Haploid number ($n$) = $\frac{\text{Diploid number}}{2}$ = $\frac{12}{2}$ = 6
Applying the Independent Assortment Principle
Independent assortment during meiosis leads to a variety of chromosome combinations in the resulting gametes. The formula to calculate the number of possible combinations is $2^n$, where '$n$' is the haploid number.
Calculating Total Gamete Combinations
Using the haploid number calculated ($n=6$):
Number of combinations = $2^n$ = $2^6$
Calculating $2^6$:
- $2^1 = 2$
- $2^2 = 4$
- $2^3 = 8$
- $2^4 = 16$
- $2^5 = 32$
- $2^6 = 64$
Therefore, there are 64 different combinations of maternal and paternal chromosomes possible in the gametes.
Important Questions from Mendelian Inheritance
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)
- The blood group of the mother is A⁺ and that of the father is AB⁺. Which of the following statements is/are correct?
- 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 ________.
A pedigree of an inheritable disease is shown below.
- In tomato plant, red (R) is dominant over yellow (r) for fruit color and purple (P) is dominant over green (p) for stem color. Fruit color and stem color assort independently. The number of progeny plants of different fruit/stem colors obtained from a mating are as follows:
Red fruit, purple stem - 145
Red fruit, green stem – 184
Yellow fruit, purple stem - 66
Yellow fruit, green stem - 47
What are the genotypes of the parent plants in this mating?
