From base order to protein shapeSpec 3.7B
In short
The order of bases in a gene decides the order of amino acids in a protein. The chain of amino acids then folds up in a way that depends on that order, giving a specifically shaped protein. The shape decides what the protein can do; for example, an enzyme's active site must have a shape that fits its substrate.
A gene is a section of DNA that codes for a specific protein. Proteins are made of chains of amino acids. The order of bases in a section of DNA decides the order of amino acids in the protein.
- The sequence of bases in the gene decides the order of amino acids.
- The chain of amino acids folds up.
- The way the chain folds depends on the order of the amino acids, so it produces a specifically shaped protein.
The shape of a protein matters because it decides what the protein can do. For example, an enzyme has an active site with a shape that fits its substrate. A different order of bases would give a different order of amino acids, a differently folded protein and so a different shape.
Show the full chain of ideas in your answer: order of bases, then order of amino acids, then folding, then specific shape, then function.
Written and checked against the Edexcel GCSE Biology (1BI0) specification · Updated October 2026