Sabtu, 07 Agustus 2010

How to Memorize Translation Table in an Easier Way

Translation table is common to all biology students which functions to explain in which forms of amino acids do the codon triplets translated. This amino acids is then assembled in a such
sequence and also foleded in such way to make proteins, the machinery of life. I oftenly heard that many student said memorizing translation table is so difficult, and some other said it's almost impossible. Actually such a table is not necessary to be memorized because I think it's kinda silly since we have all the database. But biology students who want to join IBO, for example, need to memorize that because translating codons becomes one of the question. Thereby, I posted this note with a hope that it can help biologist and biology student who are concerning about codons.

Okay, first of all I posted the image above and please take a look at it for a moment. In that image there're notations of ribonucleotides which are represented by their nitrogenous bases. There are 4 nitrogenous bases consist of Adenine (A); Guanine (G); Cytosine (S, instead of C because I wrote it in an Indonesian notation); and Uracil (U). After that, please take a look at the circle diagram. It consist of three regions of ribonucleotide notations and three of those nucleotides -the inner, middle, and outer ribonucleotides respectively- make one set of codon. So there are 64 codons can be made from those ribonucleotide triplets, while there are only 20 standard amino acids as the basic building blocks of protein. That's why one or more amino acids have a triplet redundancies. Below the diagram I also wrote the three-letter and one-letter symbols of amino acids. Those are standard notations for amino acids and I'm sure we have known for that.

After watching details of the image, then try to split up the circle into 4 quadrants and name them. Example, start the first quadrant in the Adenine inner region (A) and then clockwisely to the second (G) and so on. Thereby you'll get "AGUS" notations for the inner circle region. Continue for the middle and outer region in the same way and you'll get "USAG" notations. Now let's go to the main problem, memorizing amino acids for each triplets. Well take a look that in this order, more than one triplets are clumped into one region of amino acid. So instead of memorizing 64 triplets, we only have to memorize 20 regions of amino acids coded by those triplets. Easier isn't it? Next, memorize the number of triplets for each amino acid region and combine them just like a combination number. Example, if you start in the first quadrant (A quadrant), you'll get 3-1-4-2-2-2-2 combination code. That 7-digit code stands for 7 different amino acids and each digit represents the sum of codon triplets which making one type of amino acids. After that, memorize the amino acids just like the sequence of the combination number and you can make a short names or just memorize the one letter symbol. I prefer making short names because one-letter symbols sometimes phonemly don't match the pronounciation of the amino acid names and might causing mistaken memorizing. So, the code 3-1-4-2-2-2-2 stands for Il-Met-Th-As-Ly-Ser-Arg and means that 3 triplets (AUU, AUS, AUA) making Isoleucine, 1 triplet (AUG) making Methionine or start codon, and so on. With this way, you only have to memorize the combination number and the amino acid names per quadrant, easier than 64 randomly ordered triplets.

Some additions:
- Quadrant II (G region): 4-4-2-2-4 stands for VADEG (one letter symbol for Valine, Alanine, Aspartate, Glutamate, Glycine)
- Quadrant III (S region): 2-2-4-2-2-2-1-1 stands for Phe-Leu-Ser-Tyr-Stop2-Cys-Stop1-Tr(y)p
- Quadrant IV (U region): 4-4-2-2-4 stands for Leu-Pro-His-Gln-arg

Important !!
To name the triplet-to amino acid correctly, you really need to place those ribonucleotides notations in a correct order. So I suggest to practice making the circle and place the notations. After that you can continue by placing the regions, codes, and amino acids.

Hope this can be helpful in helping friends who's troubled by translation table.


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