What is the Phenotype Ratio of Offspring when a Roan Cow and Red Cow are Mated?

Understanding Phenotype Ratio

Phenotype ratio refers to the ratio of different physical characteristics or traits that are observable in the offspring of a genetic cross. In this case, we are looking at the phenotype ratio of offspring when a roan cow (RW) and a pure red cow (RR) are mated.

Genotype and Alleles

In genetics, genotype refers to the genetic makeup of an organism, which consists of the alleles inherited from its parents. The alleles for coat color in cows can be represented as R (red) and W (white) in this case. A pure red cow has a genotype of RR, meaning it has two red alleles, while a roan cow has a genotype of RW, meaning it has one red and one white allele.

Phenotypic Expression

The phenotype is the physical expression of the genetic traits, such as the color of the cow's coat. When a pure red cow (RR) and a roan cow (RW) are mated, the offspring inherit one allele from each parent. The red cow can only contribute a "R" allele, while the roan cow can contribute either a "R" or "W" allele.

Phenotype Ratio Calculation

Since the red cow can only pass on the "R" allele and the roan cow can pass on either "R" or "W" allele, each offspring has a 50% chance of inheriting a "R" allele from the red cow and a 50% chance of inheriting a "R" or "W" allele from the roan cow.

This results in a phenotype ratio of 1:1, where half of the offspring will have a pure red coat (RR genotype) and the other half will have a roan coat (RW genotype). This equal distribution is due to the combination of alleles from both parents, leading to a balanced phenotype ratio in the offspring.

Understanding phenotype ratios in genetic crosses can help predict the likelihood of certain traits appearing in the offspring and contributes to the study of inheritance patterns in genetics.