TRANSLATION

=Translation= [image:http://i.imgur.com/TwHEey9.png] Translation is the process in which the mRNA code is translated into a sequence of amino acids that fold-up into a protein. In the cytoplasm, a ribosome will attach onto the mRNA. Ribosomes contain short sequences of RNA known as ribosomal RNA (rRNA) that help the ribosome to recognise and bind to the mRNA. A ribosome is made of two parts (sub-units) that lock around the mRNA. The Ribosome reads the mRNA three bases at a time, each set of three bases is known as a codon. The first codon is always AUG; this signals the Initiation of translation. [image:http://i.imgur.com/KhSKNwV.png] Special Transfer RNA molecules (tRNA) carry the amino acids that will be used to make a protein, into the ribosome. At the base of each tRNA molecule is a specific sequence of three bases known as an anticodon (see below). The ribosome will match these anticodons with their complementary codons found on the mRNA molecule. The type of amino acid a tRNA carries is specific to its’ anticodon sequence. Thus the original sequence of bases on the DNA (triplets) has been transcribed into mRNA (codons) and then translated (by matching tRNA anticodons) into a chain of amino acids. This specific sequence of amino acids will fold up into a particular protein with a specific shape and function. ==Translation -Step by Step== [image:http://i.imgur.com/SCACVu9.png] [image:http://i.imgur.com/3ME43sX.png] Each codon will code for a specific amino acid. Each amino acid will have slightly different properties and will affect the way the polypeptide chain folds up into a protein. The sequence of amino acids determines the shape of the protein which in turn is responsible for its function. The codon AUG signals the start of transcription and codes for the amino acid Met = Methionine. Also UAA, UAG, UGA do not code for amino acids, these codons signal the termination of translation. Finally you will notice that while there are 64 different possible codons, there are only 20 different amino acids. Thus some codons code for the same amino acid known as the ''redundancy of the genetic code''. However if the code was read two bases at a time, there would not be enough different possible combinations to code for all of 20 amino acids. Extra for experts: Codons that code for the same amino acid tend to differ by the third base only… this is because the third base in each AntiCodon interacts more weakly or less specifically with its mRNA codon. Thus for some codons - anticodons the third base does not matter. This is known as ‘wobble’ because the third base does not always bind so specifically.