AGCTU, and all-important proteins

[Vance]

<1> Can anyone tell me where these alphabets come from ?
I mean who first used them to talk about genes' base ?
<2> All life on Earth is proteins but is there any life without proteins ?
Would you, biologists please tell me how you study enzymes in your labs ?
I am not majoring in biology, I don't know exactly about how you do that ?
Can you help me ?

Thank you,

 

[Adrian]

A, C, T, and G are abbreviations for the 4 bases of the nucleotides of DNA: Adenine, Cytosine, Thymine, and Guanine.

A, C, U, and G are abbreviations for the 4 bases of the nucleotides of RNA: Adenine, Cytosine, Uracil, and Guanine.

Just to pre-empt any possible misunderstandig : These are NOT genes; genes are long DNA sequences of such nucleotides that code for either a protein or a piece of RNA.

As to your second question, there are no known life forms that do not contain any protein. Protein both as a structural element and as enzymes is essential to organic life on Earth as we know it.
However, the definition of life - i.e. anything that displays certain characteristics like order, metabolism, growth / development, response to the environment, regulation of the internal environment, reproduction, and evolutionary adaptation - is open to very different kinds of life as well. For example, if we ever build robots that can get their energy from seeking out an consuming some kind of "food" and assemble copies of themselves from raw materials etc., that should certainly qualify as life. Such robots will not be built anytime soon, but this example should illustrate what I mean. Proteins are not a theoretical pre-condition for somethig to pass for a life form, yet all life forms we know on Earth utilize proteins. Indeed, even life-like chemical structures that don't actually constitute life forms - viruses - require proteins to function.

 

[Vance]

Thanks Adrian a lot,