Today in class we practiced monohybrid crosses of genes and alleles. They can look like this:
or like this:
It doesn't really matter which direction this four square is turned the outcomes will be the same. In these two examples the cross was between heterozygous genes which are a mix of a dominant and a recessive allele (this is review from the Hardy-Weinberg). This monohybrid cross of genes however can be between homozygous recessive (aa) and dominant (AA) as well.
There are phenotype ratios which are 3:1 for the heterozygous examples shown above because three displayed a purple flower or a smooth pea and one did not.
The genotype ratio, however was 1:2:1 this means there are one set homozygous for dominant alleles and there is two heterozygous and one for a set of homozygous recessive alleles.
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