Who came first? DNA or proteins?

Question

In living organisms DNA codes for proteins. But for DNA to function it needs proteins. If there isn't DNA transcription and translation there are no proteins. But for DNA transcription and translation to occur, proteins are needed. Who came first?

Answer 1

As with almost all "which came first" questions the answer is simple: Neither one "came first" ... they evolved together.

It's like asking, "which came first, the English language, or English speakers?" Neither one can exist without the other. But both evolved from earlier things that would not be now called "English" ... but once the language evolved to the point where we would call it "English", then at that point we would call the speakers of that language "English speakers."

DNA is like the English language, and proteins are like English speakers.

I disagree with people that say "proteins" came first. DNA isn't just a bunch of proteins strung together. Proteins are geometrically very complex (they twist and bend in all sorts of complex ways, which gives them their unique properties) but not stable in very long strands, while DNA is geometrically quite simple (a simple double-helix), but far more stable for incredibly long strands. So DNA is a molecule that encodes the structures for many many proteins. So the asker is right that DNA doesn't have much purpose without proteins, and proteins in modern organisms can't be encoded without DNA.

So what probably happened is that RNA came before both DNA and proteins. RNA is a pretty good (but not a great) catalyst, and a pretty good (but not a great) replicator. Protein is a much better catalyst, but a lousy replicator. And DNA is a fantastically robust replicator, but a lousy catalyst.

So both DNA and proteins probably grew together as complimentary offshoots to RNA. The proteins provided much better catalysis for much more complex functions. And DNA provided a much better medium for storing many, many proteins. And RNA continued to be the intermediary between them.

And this system; DNA-RNA-proteins was such a successful system, that it allowed for the formation and inheritance of an almost unlimited set of functions ... and became the basis for all of modern life.

Answer 2

Bill Bryson says it the best in his book A Short History of Nearly Everything. If you can't afford the time to read the book then by it on CD or tape. If I remember correctlly, he states that the unbelievable odds of nucleic acids even coming together and forming is space greatly challenging. Once upon a time an experiment using lightining and certain gases together in a vacuum performed way back when - but results never duplicated, resulted in a few nucleic acids. Bryson compares the odds of matching the four nucleic acids of DNA with their corresponding amino acid - and you have to consider redundancy - then he makes the comparison to a gambling casino wheel and how it would not happen if certain wheels are not held, but the odds are more favorable if you hold those wheels.

Basically to summarize

- Your question is really out there and that is why you should read this book - I promise you it will blow your mind.

- You have consider that proteins are made of amino acids and DNA is made of nucleic acids. The elements of each of the amino acids and nucleic acids would have to come together first. There are less nucleic acids than amino acids, so this should be taken into the equation.

-Then a nucleic acid triplet by the way, would have to code for more than one amino acid at least.

Your problem is very complex - read the book!

Answer 3

Proteins

Answer 4

RNA came first. strands of RNA were "naturally selected" based on their ability to copy themselves and denature in certain environments of monomers. as amino acids began to weakly bind to the bases or RNA some small proteins were formed that may have given RNA advantages in copying themselves. RNA came before both DNA and proteins, but it seems like proteins were formed first and RNA was the first genetic material for protobionts and other extremely early forms of life. nucleic acids require more kinds of elements to form while proteins require less (usually) as well

Answer 5

Proteins were discovered first, but both were probably made at the same time

Answer 6

simple proteins . then they bound together to become DNA

Answer 7

The chicken or the egg?! Who knows?!

Answer 8

check out the message board for rosetta .........http://boinc.bakerlab.org/rosetta/

Answer 9

protiens