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. The process is broadly divided into two phases: transcription and translation. During transcription, a section of DNA encoding a protein, known as a gene, is converted into a molecule called messenger RNA (mRNA) by enzymes called RNA polymerases, which occur in the cell nucleus. In eukaryotes, this mRNA is initially produced in a premature form (pre-mRNA) and undergoes post-transcriptional modifications to become mature mRNA, which is then exported from the nucleus via nuclear pores to the cytoplasm for translation. During translation, ribosomes read the mRNA and use its nucleotide sequence to determine the sequence of amino acids, catalyzing the formation of covalent peptide bonds to build a polypeptide chain. After translation, the polypeptide chain must fold to form a functional protein; for example, an enzyme requires correct folding to produce an active site. Folding first involves forming smaller secondary structures, which then fold into the overall three-dimensional tertiary structure. Once correctly folded, the protein can undergo further maturation through post-translational modifications that alter its function, cellular location, or ability to interact with other proteins. Protein biosynthesis plays a key role in disease, as errors from DNA mutations or protein misfolding often underlie illnesses. DNA mutations alter the mRNA sequence, which changes the encoded amino acid sequence, potentially shortening the polypeptide chain via a premature stop sequence or changing a specific amino acid. Such changes can impair protein function or folding, and misfolded proteins tend to form dense clumps implicated in neurological disorders like Alzheimer's and Parkinson's disease. Transcription occurs in the nucleus using DNA as a template. In eukaryotes, the initial mRNA is pre-mRNA requiring post-transcriptional modifications, whereas prokaryotes produce mature mRNA directly. A helicase enzyme first disrupts hydrogen bonds in the DNA double helix, unwinding a region corresponding to a gene and exposing bas
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- Molecular biology
- known_for
- Core biological process of protein production via transcription and translation
Lore & Background
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. The process is broadly divided into two phases: transcription and translation. During transcription, a section of DNA encoding a protein, known as a gene, is converted into messenger RNA (mRNA) by enzymes called RNA polymerases in the nucleus. In eukaryotes, this mRNA is initially produced in a premature form (pre-mRNA), which undergoes post-transcriptional modifications to produce mature mRNA. The mature mRNA is then exported from the cell nucleus via nuclear pores to the cytoplasm for translation. During translation, ribosomes read the mRNA and use its nucleotide sequence to determine the sequence of amino acids, catalyzing the formation of covalent peptide bonds to build a polypeptide chain. Following translation, the polypeptide chain must fold to form a functional protein, first forming secondary structures and then a three-dimensional tertiary shape. The protein can then undergo further maturation through post-translational modifications, which alter its function, location within the cell, or ability to interact with other proteins. Protein biosynthesis plays a key role in disease, as changes and errors—through DNA mutations or protein misfolding—are often underlying causes. Mutations can alter the mRNA sequence, changing the encoded amino acid sequence or generating a stop sequence that causes early termination, impacting the protein’s ability to function or fold correctly. Misfolded proteins tend to form dense clumps, implicated in neurological disorders such as Alzheimer’s and Parkinson’s disease.
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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