In this deck, you will learn about genetic inheritance. We will explore how characteristics are passed from parents to offspring, and define the essential vocabulary you need for your GCSE exams, such as gene, allele, genotype and phenotype. We will also look at how to predict inheritance and understand how some genetic disorders are passed on.

Inside the nucleus of your cells, you have chromosomes, which are long molecules of DNA. A gene is a short section of DNA on a chromosome. Each gene contains the instructions to make a specific protein, and these proteins control our characteristics, like our eye colour or blood type.

For a particular gene, there can be different versions. For example, the gene for eye colour can have a version for blue eyes and a version for brown eyes. These different versions of the same gene are called alleles.

Alleles can be dominant or recessive. A dominant allele is always expressed, even if you only have one copy of it. We represent it with a capital letter. A recessive allele is only expressed if you have two copies of it. It is represented by a lower-case letter. If a dominant allele is present, it will always mask the effect of a recessive allele.