I had, like I still do, assumed that the RNA hypothesizes (which is that life first had RNA and no DNA and DNA only evolved later from RNA ) is correct and that what appears to be the best abiogenesis theory is that the first viable protocell probably had RNA-like molecules with no protein or DNA and that RNA simultaneously acted as genetic material and enzyme function. But, until now, I didn't think there was much direct empirical evidence that RNA could readily act like an enzyme and that bothered me because that meant that there was quite a large room for rational doubt of that hypothesis in my mind.
But now I find that room for rational doubt is removed because I have just discovered that there is actually very strong evidence that RNA can readily act just like an enzyme and this has been a known scientific fact for many years:
http://en.wikipedia.org/wiki/Ribozyme
“...A ribozyme (ribonucleic acid enzyme) is an RNA molecule that is capable of catalyzing specific biochemical reactions, similar to the action of protein enzymes. ...”
And now I was surprised to discover that ribosomes, the enzyme that is central in making proteins, is mostly made of RNA and NOT amino derivatives:
http://en.wikipedia.org/wiki/Ribosomal_RNA
“...the predominant material within the ribosome, which is approximately 60% rRNA and 40% protein by weight. ...”
Now, the point here is this fits in perfectly with the hypothesis that once there was protocells with no protein and that RNA simultaneously acted as genetic material and functioned like enzymes because, if that wasn't the case, I think it would be quite difficult to explain why the ribosomes evolved to have any RNA in it at all if you assume it evolve from a pure protein i.e. an enzyme with no RNA. But if you start off with the assumption that first there was no protein in living cells, just RNA, and only LATER cells evolved to produce proteins, that would make absolute perfect sense because the first enzyme to synthesis proteins, i.e. ribosome, in a similar way to modern ribosomes do, HAD to be made of just RNA else we would have the chicken and egg problem of which came first, protein synthesis that including the synthesis of ribosome protein itself, or the ribosome protein itself? And, as soon as you assume that the first ribosome was just made of RNA, it makes sense that most of it still is made of RNA because that is the way evolution typically works i.e. evolution generally doesn't make a complete overhaul of the structure of something but rather tends to builds on what it has made before.
Thanks to this, I am now more certain than ever that this is the correct hypothesis i.e. the first viable protocell had no protein nor DNA and only had RNA-like molecules and only needed RNA-like molecules to be viable. Then modern RNA evolved from that. Then cells evolved to make proteins. Then DNA evolved from RNA. What a nice neat picture!
Originally posted by humyBackward thinking, indeed. Modern science has already determined that RNA comes from DNA.
I had, like I still do, assumed that the RNA hypothesizes (which is that life first had RNA and no DNA and DNA only evolved later from RNA ) is correct and that what appears to be the best abiogenesis theory is that the first viable protocell probably had RNA-like molecules with no protein or DNA and that RNA simultaneously acted as genetic material and enzyme ...[text shortened]... that. Then cells evolved to make proteins. Then DNA evolved from RNA. What a nice neat picture!
Originally posted by RJHindsI accidentally unblocked your post and thus saw it but I decided will respond to just this post:
Backward thinking, indeed. Modern science has already determined that RNA comes from DNA.
I assume what your are talking about is mRNA being coded from DNA from the cell nucleus of a modern day cell. But that is totally irrelevant to how RNA evolved or came into existence in the first cell that had RNA. You are moronically confusing the two totally different things i.e. confusing the evolutionary origins with the modern day metabolic origins. Obviously "evolutionary" doesn't equate with "metabolic".
Actually, your attempt to confuse the two wouldn't work anyway because sometimes the metabolism works the other way around at least when viruses infect i.e. RNA codes for DNA instead of the other way around. this is well known in biology as "reverse transcription" and, just like enzymes translates DNA into RNA, there are enzymes that translate RNA into DNA:
http://en.wikipedia.org/wiki/Reverse_transcriptase
"'...
Reverse transcriptase (RT) is an enzyme used to generate complementary DNA (cDNA) from an RNA template, a process termed reverse transcription. RT is needed for the replication of retroviruses
.."
In addition, as if your post wasn't idiotic enough, your statement that "RNA comes from DNA" is strictly false anyway because it doesn't "come" from DNA but rather it is "coded by" DNA. This is because DNA doesn't "make" RNA but rather an enzyme makes it from scratch by connecting nucleotides that do NOT originate from the DNA itself and uses DNA merely as a template to determine the sequence of RNA bases so that they merely correspond to the DNA base pairs. Without that enzyme, cells with DNA would not create RNA (and the cell would die ) because, strictly (and correctly ) speaking, DNA itself doesn't actually "make" anything! (although I have seen some of the poorer quality science text books erroneously use the word "make" here, the better ones don't )
If you refute these well known biological fact, just see:
http://en.wikipedia.org/wiki/RNA_polymerase
"...RNA polymerase (RNAP or RNApol), also known as DNA-dependent RNA polymerase, is an enzyme that produces primary transcript RNA. In cells, RNAP is necessary for constructing RNA chains using DNA genes as templates, a process called transcription...."
-thus it says an enzyme makes the RNA, NOT the DNA itself which is merely used as a template.
As usual, there is just so much wrong and idiotic with your post.