Genes are the cell’s instruction manuals. Most genes carry the information needed to make proteins, which are the molecules that perform nearly all cellular work. The process of turning genetic code into protein is controlled and precise. It happens in two main steps called transcription and translation. Together, these two steps are known as gene expression.

From Gene to Protein

The path from DNA to protein is the central idea of molecular biology. It describes how genetic information flows from DNA to RNA to proteins. This chain of events is often referred to as the central dogma.

Step 1: Transcription

Transcription happens in the cell nucleus. The DNA sequence of a gene is used as a template to make a new molecule called RNA (ribonucleic acid).

DNA and RNA are both made of nucleotide bases, but RNA has slightly different chemical properties. The specific type of RNA that carries genetic instructions is messenger RNA (mRNA). It serves as a temporary copy of the gene, carrying the genetic message from DNA in the nucleus to the cytoplasm.

Step 2: Translation

Translation happens in the cytoplasm. Here, the mRNA attaches to a molecular machine called a ribosome, which reads the mRNA sequence in sets of three bases called codons. Each codon codes for one specific amino acid, which is a building block of protein.

Another type of RNA, called transfer RNA (tRNA), brings the correct amino acid to the ribosome. The ribosome links the amino acids together in the order specified by the mRNA codons.

This continues until the ribosome reaches a stop codon, which signals the end of the protein. The finished chain of amino acids then folds into a functional protein.

Why It Matters

This two-step process connects the static information in DNA with the dynamic world of cell function. Every cell in your body contains the same DNA, but different cells express different genes, which means they produce different proteins. This control of gene expression is what allows for the complexity of multicellular life.

Summary

  • DNA holds the genetic code.
  • Transcription makes an RNA copy of that code.
  • Translation reads the RNA and builds the protein.

The sequence of DNA bases determines the sequence of amino acids, which determines the protein’s structure and function. This is the molecular logic that connects genes to life.

References

Genetics Home Reference: How do genes direct the production of proteins?