Why does your body need DNA at all?
Your eye colour, your blood group, and even the exact shape of many of your enzymes depend on information stored in one molecule. That molecule is DNA. When your cells need instructions for building, repairing, or running your body, they read DNA.
When you talk about DNA, you mean
the long molecule called deoxyribonucleic acid that carries the biological instructions your cells use
. Every living thing uses this same basic information system, which is why scientists say life shares a universal genetic code.
DNA matters because your cells use parts of it called genes to make proteins. Proteins do almost everything in your body, so if the DNA instructions change, the proteins can change too, and that can affect your traits. A good example is melanin production: a gene can influence how much pigment your skin cells make, which affects skin colour.
Watch out: DNA does not directly make traits by itself. Your DNA gives instructions for proteins, and those proteins help produce the traits you see.
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