Translation: Messenger RNA Translated Into Protein
Translation is the process that takes the information passed from DNA as messenger RNA and turns it into a series of amino acids bound together with peptide bonds. It is essentially a translation from one code (nucleotide sequence) to another code (amino acid sequence). The ribosome is the site of this action, just as RNA polymerase was the site of mRNA synthesis. The ribosome matches the base sequence on the mRNA in sets of three bases (called codons) to tRNA molecules that have the three complementary bases in their anticodon regions. Again, the base-pairing rule is important in this recognition (A binds to U and C binds to G). The ribosome moves along the mRNA, matching 3 base pairs at a time and adding the amino acids to the polypeptide chain. When the ribosome reaches one of the "stop" codes, the ribosome releases both the polypeptide and the mRNA. This polypeptide will twist into its native conformation and begin to act as a protein in the cells metabolism.
The steps in translation are:
- The ribosome binds to mRNA at a specific area.
- The ribosome starts matching tRNA anticodon sequences to the mRNA codon sequence.
- Each time a new tRNA comes into the ribosome, the amino acid that it was carrying gets added to the elongating polypeptide chain.
- The ribosome continues until it hits a stop sequence, then it releases the polypeptide and the mRNA.
- The polypeptide forms into its native shape and starts acting as a functional protein in the cell.
Types of RNA:
- mRNA - messenger RNA is a copy of a gene. It acts as a photocopy of a gene by having a sequence complementary to one strand of the DNA and identical to the other strand. The mRNA acts as a busboy to carry the information stored in the DNA in the nucleus to the cytoplasm where the ribosomes can make it into protein.
- tRNA - transfer RNA is a small RNA that has a very specific secondary and tertiary structure such that it can bind an amino acid at one end, and mRNA at the other end. It acts as an adaptor to carry the amino acid elements of a protein to the appropriate place as coded for by the mRNA.
- rRNA - ribosomal RNA is one of the structural components of the ribosome. Its sequence is the compliment of regions in the mRNA so that the ribosome can match with and bind to an mRNA it will make a protein from.
- The RNA World (more info)
- RNA Commentary - by Sidney Altman (1989 Nobel Laureate in Chemistry) about the probability of RNA's role in the development of early life on this planet
- Protein translation tool at ExPASy- a tool which allows the translation of a nucleotide (DNA/RNA) sequence to a protein sequence
The following resource was originally accessed through the BioSciEd Net (BEN) digital resources collection, which is the National Science Digital Library (NSDL) Pathway for biological sciences education. For more teaching resources, please visit BEN to use their searchable database. BEN is free to use, but requires registration.
- Prokaryotic Translation - this animation by MicrobeLibrary.org offers a comparison of transcription and translation processes to teach students the differences between the two processes.