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Genetics Basics

Dr Christina Vallianatos

Our bodies are made of cells, and inside nearly every cell is our DNA. Even though we have many different cells with different shapes and functions (cells in the eye vs. brain vs. kidney, etc.), they all have the exact same DNA inside. Each cell contains our entire DNA content, called our genome. This means our DNA has a lot of information to guide making our entire bodies, and also that each cell type has a different way to use only the parts of the DNA it needs. We can think of our genome like a cookbook, with recipes for our brain, our eyes, our legs, our kidneys, etc. Some ingredients are used in all recipes, some are used only in one or two recipes. Just like how cooking in different environments can change the final product (different altitude, different temperatures), so too our personal environments can influence our bodies.

A DNA mutation changes the gene, which may alter the function of that gene and change something in your body. This works the same way changing the letters of a word in your cookbook, which can change the meaning, and change how the recipe turns out. For example, instead of adding 1tsp salt you added 1tbp salt. You made the dish, but now it is much too salty. The same thing can happen in our bodies. You can still make a brain, but it functions differently now. Mutations can lead to big or small changes, it just depends on the mutation. DNA = letters Genes = words Genome = cookbook

For more information see The American Society of Genetics and these online resources.