What Are Genes?

Genes are spiraled, threadlike particles made of DNA (deoxyribonucleic acid). DNA contains the instructions for building proteins. And proteins control the structure and function of all the cells that make up your body.

Genes and the important information they carry are packaged inside chromosomes. Most cells in your body have two copies of every chromosome and, therefore, two copies of every gene: one from your mother and one from your father.

Think of your genes as an instruction manual for cell growth and function. Abnormalities in the DNA are like typographical errors. They may provide the wrong set of instructions, leading to faulty cell growth or function. In any one person, if there is an error in a gene, that same mistake will appear in all the cells that contain the same gene. This is like having an instruction manual in which all the copies have the same typographical error.