Nature is conservative (besides being a big recycler)

 Nature is conservative: indeed it maintained during the time what is in working order for a particular function.

The amazing variety of the organisms living on the hearth today originated through an extremely long evolution. As we can conclude on the basis of palaentological and other studies, evolution went ahead by trial and error. Nevertheless even nowadays the fundamental life substances are the same in every living being: from bacteria to man. 
First of all nucleic acids: RNA and DNA. 
DNA, thanks to its autoreplication ability was a basic molecule since the beginning of the life and is, still at present, the molecule containing and transferring from generation to generation genetic information.

DNA is a complex molecule but its structure and working way are exactly alike in all present and ancient organisms.  

We can compare DNA to a recipe book of the proteins the cells is able to produce.  
RNA has a similar structure; its function is to convert  the DNA information into proteins.
Proteins too are complex molecules. They are composed by  determined sequences of  “ small bricks” called amminoacids for their chemical composition.

Amminoacids are small molecules and are only 20. Nevertheless their different possible combinations form countless different proteins: distinct from species to species and even from individual to individual.

Every organism synthesizes its proteins following the “recipe” written in the DNA with a sort of universal molecular alphabet, the same for all living beings (with perhaps small, very rare exceptions) in which to every letter corresponds an amminoacid. So the sequence of the letters in a determined DNA region (I. e. a gene) corresponds to the amminoacid sequence of the protein that the gene codify.

I hope to have made myself clear about “genetic code” although using not scientific words. I used this figurative language because I have in mind the disoriented faces of many persons, not familial with biology, when I speak of  nitrogenous bases, that are 4 but work in “triplets”, of nucleotides and so on. I don’t want to imagine similar expressions in my possible readers!!

You will easily find deeper information about DNA in other blogs.

Here I would like also to remember that even many proteins are conserved in nature. For example cytochrome c, a mitochondrial  protein very important in cellular respiration, can be found in every mono and pluricellular aerobic organism with the same structure and function. Cytochrome is so highly conserved that the few structural variations evidenced in different organism groups are used for establish their phylogenetic affiliation.

So once again we learn something from Nature. On the one hand Nature indicates the importance of recycling (see post “Nature big recycler) , on the other hand suggests us to maintain and use good results and good experiences obtained in the past.