independent assortment of genes

what is the phenotype for a selfed dihybrid cross

the F2 generation would have four different types in the following proportions of

9:3:3:1

why are the phenotypes of dihybrid crosses like that

the 9:3:3:1 phenotypic ratio of dihybrid crosses is the result of two 3:1 ratios that occur on with each trait combined.

when does mendel’s law of independence apply

this law applies to genes on different chromosomes. genes on the same chromosome generally do not assort independently because they are held together by the chromosome itself

how can you arrive at the 9:3:3:1 ratio from the gamete frequency

from the f1 dihybrid we can predict that ¼ of gametes will have R;Y , ¼ R;y , ¼ r;Y , ¼ r;y.

Assembling these gametes into a punnett square, you make 16 individuals. The F2 gen carries a variety of genotypes, but there are only four phenotypes, and their proportions are in the 9:3:3:1 ratio.

what are two ways you can work with genetics

1. predicting the unknown genotypes of parents by using phenotypes ratios of progeny

2. predicting progeny phenotype ratios from parents of known genotype

what does the product rule state

that the probability of independent events occurring together is the product of their individual probabilities

what does the sum rule state

that the probability of either one or the other of two mutually exclusive (cannot happen at the same time) events occurring is the sum of their individual probabilities