The Central Dogma (Bioinformation Theory) is
Although it is the genes in the nucleus of each cell that encode all the information a ssociated with each orgnism, it is the proteins in the cell cytoplasm that perform most life functions and make up the majority of cellular structures and serve catalytic purposes (enzymes).
Proteins are large, complex molecules made up of smaller subunits called amino acids. Chemical properties that distinguish the 20 different amino acids cause the protein chains to fold up into specific 3D structures that define their particular functions in the cell.
In an oversimplified version of this process, one gene encodes for one or more proteins and therefore the human genome defines the complement of all the expressed proteins of an individual - or the proteome.
Gene Expression: Most genes are expressed as the proteins they encode in two steps:
When the two DNA strands are separated by an enzym called ``DNA polymerase'', a single stranded messenger RNA complementary to the DNA strand is formed by symbol-by-symbol mapping from portion of the DNA sequence (the template) with alphabet A,T,C,G to complementary RNA sequence with alphabet U, A, G, C. In the process, the non-coding segments, called introns, in DNA sequence are removed by splicing, and the remaining segments that encode information for protein synthsis, called exons, are put back together in the mRNA.
The information coded by the mRNA is used to proteins sythesis. The ribosomes (rRNA and other proteins) assemble the free amino acids in cytoplasm collected by tRNA into a protein chain in the order dictated by the mRNA.
Three types of RNAs:
For more information, see these pages: