Genetic Diagrams

• Genetic diagrams only show the probabilities, not what will actually happen
• All genes have different versions, called alleles
• There are two alleles of every gene in your body, one on each chromosome
• Homozygous means there are two alleles for a particular gene which are the same
• Heterozygous means the two alleles are different and only one can determine which characteristic is present. They can either be dominant or recessive
• For a recessive characteristic to be displayed, both alleles must be recessive
• For a dominant characteristic to be shown only one needs to be present as it overrules the recessive one
• The genotype is the combination of alleles you have
• Your phenotype is what characteristics are shown
• A Punnett square shows all possible combinations of genes from parents when they reproduce sexually