Protein synthesis is the cellular process of building proteins from genetic information encoded in DNA. It occurs in two main stages: transcription (DNA to mRNA in nucleus) and translation (mRNA to protein at ribosomes). This fundamental process enables cells to produce the proteins needed for structure, function, and regulation.
The first stage where RNA polymerase reads the DNA template and synthesizes a complementary mRNA strand. This occurs in the nucleus of eukaryotic cells.
Before leaving the nucleus, pre-mRNA is modified: a 5' cap is added, a poly-A tail is added, and introns are removed by splicing.
At the ribosome, mRNA codons are read and matched with tRNA anticodons carrying specific amino acids. The ribosome catalyzes peptide bond formation between amino acids.
Triplets of nucleotides (codons) specify amino acids. There are 64 possible codons but only 20 amino acids, making the code redundant (multiple codons can code for the same amino acid).
Ribosome assembles at the start codon (AUG) on mRNA. The first tRNA carrying methionine binds to the P site.
tRNAs bring amino acids to the A site, peptide bonds form, and the ribosome translocates along the mRNA.
When a stop codon is reached, release factors bind and the completed polypeptide is released.
Many antibiotics target bacterial protein synthesis without affecting human cells.
Understanding protein synthesis helps treat diseases caused by protein misfolding or deficiency.
Recombinant protein production for therapeutics like insulin and growth hormones.
Delivering functional genes to compensate for defective ones in genetic diseases.