Proteins in a cell are made through a process called protein synthesis, which occurs in two main stages: transcription and translation.
Process Overview
- Transcription takes place in the cell nucleus, where the DNA sequence of a gene is copied to produce messenger RNA (mRNA). An enzyme called RNA polymerase reads the DNA and builds the mRNA strand, which carries the genetic instructions for making a specific protein.
- Translation occurs in the cytoplasm at the ribosome. The ribosome reads the mRNA sequence in groups of three nucleotides called codons. Each codon corresponds to a specific amino acid. Transfer RNA (tRNA) molecules bring the correct amino acids to the ribosome, where they are linked together in the proper order to form a protein chain. This process continues until a stop codon signals the end of protein synthesis.
Key Cell Components Involved
- DNA : Contains the instructions for proteins.
- RNA polymerase : Enzyme that transcribes DNA into mRNA.
- mRNA : Messenger carrying the protein code from DNA to ribosome.
- Ribosomes : Cellular machines that assemble amino acids into proteins.
- tRNA : Transfers specific amino acids to ribosomes according to the mRNA code.
This process results in proteins, which are chains of amino acids folded into specific shapes that perform numerous functions in the cell such as enzymes, structural components, and signaling molecules.
