What is DNA?
A long molecule found in the nucleus of almost every cell in your body. It carries the genetic instructions that determine how living things grow, function, and look.
Think of DNA as the instruction manual for building and running a living organism. Every cell in your body — from your skin cells to your nerve cells — contains the same complete set of instructions. These instructions are written in a chemical "language" using just four molecular letters.
DNA is incredibly tiny. If you stretched out all the DNA from a single human cell, it would be about 2 metres long — yet it is coiled up so tightly that it fits inside a nucleus that is far too small to see with the naked eye.
Imagine DNA as a recipe book for a chef. Every chef in the restaurant has an identical copy of the same recipe book. Even though each chef has the whole book, they only "read" and follow the recipes relevant to their job — just like how different cells in your body only use the instructions they need.
The Structure of DNA
DNA has a famous shape called a double helix — imagine a twisted ladder. The sides of the ladder are made of alternating sugar and phosphate groups, while the "rungs" are pairs of chemical bases.
There are four bases in DNA:
- A — Adenine
- T — Thymine
- C — Cytosine
- G — Guanine
These bases always pair up in a specific way: A pairs with T, and C pairs with G. This is called complementary base pairing and it is fundamental to how DNA copies itself and passes on information.
The spiral, twisted-ladder shape of a DNA molecule, consisting of two strands wound around each other.
Use this memory trick for base pairing: "Apples in Trees, Cars in Garages" — A pairs with T, C pairs with G. Once you know one side of the ladder, you can always figure out the other!
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