GCSE Biology DNA Revision Notes

• 1DNA is a double helix structure made up of nucleotides.
• 2Each nucleotide consists of a sugar, a phosphate group, and a nitrogenous base.
• 3The four nitrogenous bases are adenine (A), thymine (T), cytosine (C), and guanine (G).
• 4Base pairing rules dictate that A pairs with T and C pairs with G.
• 5DNA replication is the process by which DNA makes a copy of itself before cell division.

DNA is like a long recipe book that contains all the instructions needed to build and operate a living organism. It is made up of smaller units called nucleotides, which are like the letters in the recipes. The order of these letters determines what proteins are made, which in turn affects how the organism looks and functions. When cells divide, DNA makes a copy of itself so that each new cell has the same instructions.