How is Protein Made?
Protein synthesis is a two-step process fundamental to all life. It starts with genetic information encoded in DNA and culminates in the creation of functional proteins, the workhorses of cells.
-
Transcription: This initial step takes place in the cell's nucleus. Here, the DNA sequence of a specific gene—a section of DNA coding for a particular protein—is copied into a messenger RNA (mRNA) molecule. This mRNA molecule acts as a blueprint for protein construction, carrying the genetic code from the nucleus to the ribosomes in the cytoplasm. As described in this article on how genes direct protein production, this process is crucial for gene expression.
-
Translation: This second step happens in the cytoplasm on ribosomes. The ribosome reads the mRNA sequence, three nucleotides (a codon) at a time. Each codon specifies a particular amino acid. Transfer RNA (tRNA) molecules, each carrying a specific amino acid, recognize and bind to their corresponding codons on the mRNA. The ribosome then links these amino acids together, forming a polypeptide chain. This chain folds into a specific three-dimensional structure, becoming a functional protein. The fundamental reaction involves the formation of a peptide bond between the carboxyl group of the growing polypeptide chain and the free amino group of the incoming amino acid, proceeding from the N-terminal to the C-terminal end. (Source).
Amino Acids: The Building Blocks
Proteins are polymers composed of amino acids. There are 20 different types of amino acids, each with unique chemical properties. (Source) The sequence of these amino acids dictates a protein’s structure and, consequently, its function. Proteins are made up of mostly hydrogen, carbon, nitrogen, and oxygen, linked together in chains. (Source)
Examples of Protein Synthesis in Action:
- COVID-19 Vaccines: Some COVID-19 vaccines utilize mRNA technology. The mRNA instructs our cells to produce the spike protein found on the surface of the SARS-CoV-2 virus. This triggers an immune response, preparing the body to fight off future infections. (Source)
- Cystic Fibrosis: In cystic fibrosis, the CFTR protein is either not made correctly or not made at all, leading to the disease's characteristic symptoms. (Source)
Protein Production in Different Organisms
The basic two-step process of protein synthesis is conserved across all organisms. However, the specifics, such as the rate of synthesis and the types of proteins produced, vary. (Source)
