Drawing genetic diagrams

When constructing a genetic diagram for a monohybrid cross, it is important to follow these conventions: Show the characteristic of the parents (phenotype). Show the alleles present in the parents’ cells (genotypes). Use upper case letters to represent a dominant allele. Use the lower case version of the same letter to show a recessive allele. Put gametes in circles. Show all the different possible combinations of alleles at fertilization. Put an ‘x’ to show a cross (mating).

Below is an example of how you might construct a genetic diagram to explain a monohybrid cross between a father who has two alleles for free earlobes and a mother who has two alleles for attached earlobes. Which conventions of drawing genetic diagrams do you recognize? Offsprings’ characteristics: all have free earlobes but have one dominant and one recessive allele