How can a gene help a cell make a protein?

A cell can use information in DNA to assemble a protein, but the DNA does not become the protein's material. A protein-coding gene supplies a sequence that can be copied into RNA. This first stage, transcription, makes a working message while the DNA remains part of the cell's genetic information.

In a cell with a nucleus, the initial RNA can be processed before a messenger RNA reaches the cytoplasm. A ribosome then works along the message in groups of three bases called codons. The order of those groups matters: it helps specify the order of the amino acids used to build a protein chain.

Transfer RNAs act as adaptors between the message and the building materials. Each carries an amino acid and has a region that can pair with an appropriate codon. At the ribosome, matching adaptors bring amino acids into place, and the amino acids are joined into a growing chain. This is translation: information in a sequence of RNA bases guides construction of a different kind of molecule.

The chain's amino acid sequence influences how it folds and interacts with other molecules. Many proteins also need processing or partners before they work. The resulting structures can help carry substances, pass signals or speed chemical reactions. The route therefore connects sequence information to molecular shape and activity, not simply to a label saying which trait appears.

Cells regulate which genes are used and how strongly. Two cells with much the same DNA can make different mixtures of proteins because they use different parts of that information. Not every gene codes for a protein, and whole traits often depend on many genes, cellular conditions and the environment. The DNA-to-RNA-to-chain route explains an important construction process within that larger system.