What is genotypic ratio in dihybrid ?

Question

Answer

To predict the genotypic ratios, recall that for each gene the ratio is 1 : 2 : 1 :: AA : Aa : aa . Then, algebraically

(1YY + 2Yy + 1yy) x (1RR + 2Rr + 1rr) = 1 YYRR + 2 YYRr + 1 YYrr + 2YyRR + 4YyRr + 2 yyRR + 1yyRR + 2yyRr + 1yyrr

That is, we expect a characteristic 1:2:1:2:4:2:1:2:1 ratio of the nine possible genotypes. These nine genotypes can be grouped into four phenotypes, for example 1 YYRR + 2 YYRr + 2 YyRR + 4 YyRr = 9Y-R- round, yellow peas. The ratio of these phenotypes is of course 9:3:3:1.

Answer

Answer

Genotypic ratio is 1:2:1:2:4:2:1:2:1

Answer

Ratio of genes

Answer

The genotypic ratio in a dihybrid cross refers to the ratio of different genotypes that can result from the combination of alleles for two different traits. In a dihybrid cross, two individuals that are heterozygous for two traits are crossed to determine the possible genotypes and phenotypes of their offspring.

Understanding Dihybrid Cross:
A dihybrid cross involves studying the inheritance of two different traits simultaneously. To understand the genotypic ratio in a dihybrid cross, we need to consider the law of independent assortment, which states that during gamete formation, the alleles for different traits segregate independently of each other.

Genotypic Ratio:
The genotypic ratio is determined by the possible combinations of alleles for the two traits being studied. In a dihybrid cross, there are four possible combinations of alleles for each trait, resulting in a total of 16 possible genotypes. However, some genotypes may be repeated, leading to a reduced number of unique genotypes.

Example:
Let's consider an example of a dihybrid cross between two plants that are heterozygous for seed color (Yy) and seed shape (Rr). The possible genotypes of the offspring can be determined by using a Punnett square.

The Punnett square for this cross would have four boxes, representing the four possible combinations of alleles for the two traits. Inside each box, the genotypes of the offspring are determined by combining one allele from each parent.

The possible genotypes in this example would be:
- YYRR
- YYRr
- YYrr
- YyRR
- YyRr
- Yyrr
- yyRR
- yyRr
- yyrr

Genotypic Ratio:
By counting the number of unique genotypes, we can determine the genotypic ratio. In this example, there are nine unique genotypes. Therefore, the genotypic ratio would be 9:1:1:3:3:3:1:1:1.

This genotypic ratio represents the relative frequency of each genotype among the offspring. It indicates the probability of inheriting a particular genotype in a dihybrid cross.

Conclusion:
In a dihybrid cross, the genotypic ratio represents the relative frequency of different genotypes among the offspring. It is determined by the possible combinations of alleles for the two traits being studied. By using a Punnett square, we can determine the genotypes of the offspring and calculate the genotypic ratio.

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