Protein synthesis is the process of converting the DNA sequence to a sequence of amino acids to form a specific protein. It involves three main steps: transcription of mRNA from the DNA sequence, initiation of the translation of the mRNA sequence to an amino acid sequence and elongation of the protein chain as the mRNA codes for additional amino acids to be added to the growing chain.
The first step in protein synthesis is the manufacture of a messenger RNA, or mRNA sequence, in the cell's nucleus. This mRNA sequence is determined by the DNA sequence, and after it is made, it is transferred to the ribosome where the rest of protein synthesis occurs. Once the mRNA sequence reaches the ribosome, transfer RNA codons, or tRNA, carry amino acids towards the mRNA chain. Each mRNA codon codes for a specific tRNA codon, and each tRNA codon carries a specific type of amino acid.
The process by which the chain of amino acids continues to grow is called elongation. As each tRNA codon carries an amino acid towards the mRNA chain, the amino acids are hydrolyzed from the tRNA codons and become bound together in a long chain, known as a protein. Termination of the growth of the protein chain occurs when a specific mRNA codon, known as a "stop" codon, is reached. When this stop codon is reached, the protein chain stops growing and is released from the ribosome so the cell can use it as needed.