The process of protein synthesis from mRNA is called translation. It involves the following steps:
1. mRNA travels to the ribosome:
* mRNA, carrying the genetic code from DNA, leaves the nucleus and travels to a ribosome in the cytoplasm.
* Ribosomes are cellular machinery responsible for protein synthesis.
2. Ribosome binds to mRNA:
* The ribosome binds to the mRNA molecule, starting at the start codon (AUG).
3. tRNA brings amino acids:
* tRNA (transfer RNA) molecules, each carrying a specific amino acid, enter the ribosome.
* Each tRNA has an anticodon that complements the codon on the mRNA.
* The first tRNA with the matching anticodon for AUG binds to the mRNA, bringing the amino acid methionine.
4. Amino acids link together:
* As the ribosome moves along the mRNA, it reads each codon one at a time.
* For each codon, the corresponding tRNA with the complementary anticodon enters the ribosome and brings its specific amino acid.
* The amino acids are linked together in a chain, forming a polypeptide.
5. Peptide bond formation:
* The ribosome catalyzes the formation of peptide bonds between adjacent amino acids, linking them into a growing polypeptide chain.
6. Elongation and translation:
* This process of codon recognition, tRNA binding, and amino acid linkage continues as the ribosome moves along the mRNA, elongating the polypeptide chain.
7. Termination and release:
* When the ribosome reaches a stop codon (UAA, UAG, or UGA) on the mRNA, the process terminates.
* The completed polypeptide chain is released from the ribosome.
8. Folding and modifications:
* The polypeptide chain folds into a specific three-dimensional structure, guided by interactions between amino acids.
* This structure determines the protein's function.
* Further modifications may occur, like adding sugar groups or other chemical groups.
In summary:
mRNA carries the genetic code from DNA, and ribosomes translate this code into a sequence of amino acids, forming a polypeptide chain. This chain folds into a specific three-dimensional structure, forming a functional protein. This process is crucial for building and maintaining all living organisms.
Key players:
* mRNA: Carries the genetic code.
* Ribosomes: Cellular machinery for protein synthesis.
* tRNA: Brings amino acids to the ribosome.
* Codons: Three-nucleotide sequences on mRNA.
* Anticodons: Three-nucleotide sequences on tRNA.
* Amino acids: Building blocks of proteins.
* Peptide bonds: Link amino acids together.
* Polypeptide chain: A chain of amino acids.
* Stop codons: Signal the end of translation.
* Protein folding: Determines the protein's function.
