Protein biosynthesis
Cellular process producing proteins via transcription and translation.
Protein biosynthesis, or protein synthesis, is a core biological process occurring inside cells that balances the loss of cellular proteins through the production of fresh proteins. Proteins perform critical functions as enzymes, structural proteins, or hormones, and the process is similar for both prokaryotes and eukaryotes with some distinct differences.
- field
- Molecular biology
- known_for
- Core biological process of protein production via transcription and translation
Lore & Background
Protein biosynthesis can be divided into two phases: transcription and translation. During transcription, a section of DNA encoding a protein (a gene) is converted into messenger RNA (mRNA) by RNA polymerases in the nucleus. In eukaryotes, this mRNA is initially produced as pre-mRNA, which undergoes post-transcriptional modifications—including addition of a 5' cap, a 3' poly(A) tail, and removal of introns via splicing—to form mature mRNA. The mature mRNA is exported to the cytoplasm for translation.
Reader's Guide
During translation, ribosomes read the mRNA in a 5'-3' direction and use transfer RNAs to deliver amino acids, forming a polypeptide chain. After translation, the chain must fold into secondary structures and then a tertiary structure to become functional. Post-translational modifications can alter the protein's function, location, or interactions. Errors in protein biosynthesis, from DNA mutations or protein misfolding, are often underlying causes of disease, including neurological disorders such as Alzheimer's and Parkinson's disease. Mutations can change the amino acid sequence or cause early termination, leading to misfolded proteins that form dense clumps.
Did You Know?
- RNA polymerase builds pre-mRNA at a rate of 20 nucleotides per second, enabling production of thousands of pre-mRNA molecules from the same gene in an hour.
- In eukaryotes, transcription occurs in the nucleus while translation occurs in the cytoplasm; in prokaryotes, both occur in the cytoplasm.
- Misfolded proteins have a tendency to form dense protein clumps implicated in neurological disorders including Alzheimer's and Parkinson's disease.
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