Saturday, February 26, 2011

What exactly code is all about?


The unit of the genetic code (the code in which genetic information is carried by DNA and messenger RNA. This information determines the sequence of amino acids in every peotein and thereby controls the nature of all proteins made by the cell. The genetic code is expressed by the sequence of mucleotide basesin the nucleic acid molecule, a unit of three consecutive basis(a codon) coding for each amino acid. The code is translated into protein at the ribosomes. Any changes in the genetic code results in the insertion of incorrect amino acids in a protein chain, giving a neatation) that determines the synthesis of one particular amino acid. Each codon consists of a section of the DNA molecule and the order of the codons along the molecule determines the order of amino acid in each protein made by the cell.

Friday, February 25, 2011

What is codon?

Codon is a medical term. From medical dictionary's definition we get, "A sequence of three adjacent nucleotides constituting the genetic code that specifies the insertion of an amino acid in a specific structural position in a polypeptide chain during the synthesis of proteins "

After the toy of DNA was revealed by Author Technologist and Francis Wrick, who utilised the empiric inform of Maurice Biochemist and Rosalind Printer (among others), real efforts to believe the nature of the encryption of proteins began. George Physicist postulated that a three-letter codification moldiness be hired to write the 20 acceptable alkane acids utilized by experience cells to encode proteins, because 3 is the smallest number n specified that 4n is at minimal 20.[2]

The fact that codons exist of threesome DNA bases was firstly demonstrated in the Cramp, Brenner et al. inquiry. The prime interpretation of a codon was done by Statesman Nirenberg and Heinrich J. Matthaei in 1961 at the Domestic Institutes of Wellbeing. They utilised a cell-free scheme to interpret a poly-uracil RNA ordering (i.e., UUUUU...) and revealed that the polypeptide that they had synthesized consisted of only the group elvis phenylalanine. They thereby deduced that the codon UUU specific the paraffin acid phenylalanine. This was followed by experiments in the laboratory of Severo Ochoa demonstrating that the poly-adenine RNA succession (AAAAA...) coded for the polypeptide, poly-lysine.[3] and the poly-cytosine RNA film (CCCCC...) coded for the polypeptide, poly-proline.[4] Thus the codon AAA fixed the group resolvent lysine, and the codon CCC specified the amino lsd proline. Using different copolymers most of the remaining codons were then discovered. Extending this occupation, Nirenberg and Philip Leder revealed the triplet nature of the genetic cipher and allowed the codons of the definitive tRNAs to the ribosome. Leder and Nirenberg were healthy to ascertain the sequences of 54 out of 64 codons in their experiments.[5]

Subsequent win by Har Gobind Khorana identified the repose of the transmitted code. Presently thereafter, Parliamentarian W. Holley discovered the scheme of designate RNA (tRNA), the adapter material that facilitates the treat of translating RNA into catalyst. This transform was based upon early studies by Severo Biochemist, who received the Altruist accolade in 1959 for his affect on the enzymology of RNA reasoning.[6] In 1968, Khorana, Holley and Nirenberg received the Philanthropist Honour in Physiology or Agent for their utilize