A creationist on where the genetic code came from

I guess you don't get too much in depth discussion in creationist molecular biology circles (tee-hee!) of the catalytic mechanism of peptide bond formation within ribosomes and the fact that it is in fact ribosomal RNAs that are critical rather than ribosomal proteins. While it hasn't been proven yet it is more likely that functional catalytic RNAs (probably self replicating) were around before either DNA OR proteins became the major components of evolving life.

Nucleic acids do not NEED proteins to replicate, the proteins just make it more efficient. And many nucleic acids (especially RNAs with particular secondary structures) have catalytic activity that can cut/paste/prime other nucleic acids.

RNA came first, then ribosomally-synthesized protein, then DNA.
(Non-ribosomally synthesized protein may have been around earlier, but since it has no way to self-replicate, could not really be counted as "life.")

Chez wha?

I seem to recall from high school that DNA is a protein...

The original creationist claim from which this video is culled is CB015

- JS

this person is just clueless about cell biology...new edition of "the Alberts" to come out in 2008....

Right. Let's analyse this. A quick summary might be "Proteins need DNA to be manufactured. DNA needs proteins to be manufactured. How could they have originated at the same time? God did it."

This has several logical errors:
1. It presumes the present interrelationship of DNA and proteins is the only possibility. However, it's entirely possible that one is a replacement for a simpler original scheme (that was outcompeted) by the gradual addition of parts, that simple proteins might exist that could catalyse themselves, that the precursor of DNA could replicate without proteins, but became more stable after co-opting proteins to assist itself, or many other possibilities. False dichotomy.

2. A related error to point 1, is that it also presumes that either DNA or proteins must have been original. In fact, biological systems often evolve through gradual addition of parts, and very often lose the original part at some point when the other parts take over its function more efficiently. Again, a false dichotomy.

3. This is, of course, a variation of part of Behe's Irreducible Complexity arguement. If we look here: http://www.talkorigins.org/faqs/dover/day10pm2.html - Behe's testimony in Kitzmiller vs. Dover Area School District et al - and I'm afraid Behe's a pompous ass who babbles on and on, we see him say:

So in molecular machines, in aggregates of proteins, all of the proteins which are sticking together have to have all these complementary surfaces in order for them to bind their correct partners. If they do not have the complementary surface, they don't bind and the molecular machine does not form. Now, interestingly, remember Darwin's theory says that evolution has to proceed in small steps, tiny steps.

Well, one way something like this might form is by, you have to have mutations that might produce each of these interactions at a time. For example, I think there's a quotation from an article in Nature which kind of make this point, and I'll explain it after I quote it, it's from an article by a man named John Maynard Smith, who is a very prominent evolutionary biologist who died about a year ago I believe, and he wrote in a paper called Natural Selection and the Concept of a Protein Space, which was published in Nature in 1970, "It follows that if evolution by natural selection is to occur, functional proteins must form a continuous network which can be traversed by unit mutational steps without passing through nonfunctional intermediates," and by unit mutational steps, we mean each of those pluses, each of those H's, each of those OH's and so on that I showed you in that little cartoon drawing on the previous slide.

If for example a mutation came along that changed a positive into a negative charge and disallowed an interaction that needed to occur, that would be a detrimental one. John Maynard Smith is saying that we need to proceed, you know, one step at a time. So the point is that those little colored squares are enormously complex in themselves, and further the ability to get them to bind specifically to their correct partners also requires much more additional information. It is not a single step phenomenon. You have to have the surfaces of two proteins to match.

Q.

A difficulty of getting two changes at once?

A. Yes, that's exactly right. If you can do this one tiny, tiny step at a time, then Darwinian evolution can work. If you need to make several changes at once, two, three, four, there were multiple interactions that were required for those two proteins to bind. If you need multiple interactions, the plausibility of Darwinian evolution rapidly, rapidly diminishes.

To save space, I'll use the Judge's findings on the case for the rebuttal to this. Two short quotes:

ID proponents primarily argue for design through negative arguments against evolution, as illustrated by Professor Behe's argument that "irreducibly complex" systems cannot be produced through Darwinian, or any natural, mechanisms. However, we believe that arguments against evolution are not arguments for design. Expert testimony revealed that just because scientists cannot explain today how biological systems evolved does not mean that they cannot, and will not, be able to explain them tomorrow.

Professor Behe admitted in "Reply to My Critics" that there was a defect in his view of irreducible complexity because, while it purports to be a challenge to natural selection, it does not actually address "the task facing natural selection." Professor Behe specifically explained that "[t]he current definition puts the focus on removing a part from an alreadyfunctioning system," but "[t]he difficult task facing Darwinian evolution, however, would not be to remove parts from sophisticated pre-existing systems; it would be to bring together components to make a new system in the first place." Id. In that article, Professor Behe wrote that he hoped to "repair this defect in future work;" however, he has failed to do so even four years after elucidating his defect.

As we can see, not only is this a classic creationist canard, it's one that the primary proponent admitted was false.

...I'm afraid the formatting of Behe's testimony was slightly off, but it should be obvious enough where it ends. Sorry!

I seem to recall from high school that DNA is a protein...

No. Proteins are made of linked monomers of amino acids, organic chemicals with an amine group (Nitrogen and Hydrogen) on one side and an acid (COOH) on the other. The amine group of one amino acid forms covalent bonds with the acid of the next amino acid in the chain.

DNA is also made up of linked monomers, but DNA's monomers are deoxyribose (a sugar) with a nitrogenous base and a phosphate group attached. An Oxygen atom on the deoxyribose attaches to the phosphate group of the next unit in the chain, and the bases all stick out on the side of the chain.

From the perspective of elements, both DNA and proteins contain Carbon, Oxygen, Hydrogen and Nitrogen. Proteins almost never contain Phosphorus; DNA one atom of Phosphorus per base. Some amino acids include Sulphur; DNA never contains Sulphur.

My answer, in the less than required 500 characters:

"Religion in this question is bigotry. But it is misleading, so I will answer. The basic cell is abiogenesis, not evolution on replicators. But scientists have tentative answers. RNA is the intermediate to make proteins. It is a hereditary molecule in some virus/organelles. DNA is stabler and makes larger genomes. So it is most likely that DNA is later. RNA function like proteins. The core of the ribosome that makes protein is RNA. This molecular fossil implies that RNA also came before proteins."

But the shorter explanations here are much more preferable.

In my high school biology class (read this and weep), I distinctly remember the biology teacher telling the class earnestly that, in fact, proteins are toxic, that your body may "crave" proteins, but they were like sugar or fat or salt and not really very good for you, and the reason why you always have to pee after you have a meat meal is to get rid of all the poisons you had just eaten. His words. In retrospect, I very much wonder what exactly he thought people's bodies were made of.

Hardly any wonder that so many people out there get confused, if they had any sort of "education" like that.

Well, it is thought RNA came before DNA, so I suppose the answer would be "protein" came before DNA.

Perhaps the creationists can now answer the question, where did God come from?

Thanks, TheBrummell, for saying what I was about to say!

If anyone would like a refresher on molecular biology, I can heartily recommend Larry Gonick and Mark Wheelis's Cartoon Guide to Genetics.

This is the perfect example of creationist anti-science. We've got a BIG problem in science. It's a real thinker. A brain buster.

What do creationists do? "Look! I found God!"

What do scientists do? they try to solve it!

This points out the fatal flaw in creationism. It is fundamentally, and stubbornly, incurious. In its eyes, all difficult problems are proofs of God. They are not interesting scientific problems to be solved. In fact, solving the problems makes their God smaller, since they've so cabined God in that he cannot work through the natural processes of the universe. Their God is already so small that he cannot have used the levers of evolution to create man in his image. They have to defend their wooden, inflexible God with all their might, because if a natural explanation for the origins of life is found, well, *POOF* Their God disappears.

Making protein does not require DNA (or RNA, for that matter). All of the enzymatic reactions necessary to create a protein--synthesis of amino acids, formation of peptide bonds, can be carried out by other proteins. There are numerous biological examples of polypeptides (essentially small proteins) that are created by other proteins, without ever having been coded in DNA or ever seeing a ribosome.

The whole DNA/RNA/ribosome system is basically a programmable assembly line for making proteins, but a computerized factory is no more a necessity to build a protein than it is to build a car. It's a big advantage, to be sure (which is why hand-built automobiles are virtually nonexistent these days), but that doesn't have to be the way it was first done.

Which came first, nucleic acid or protein, is very much a live question in origin of life research, but it is not a chicken-or-the-egg question. In principle, either one of them could have come first. You could have a metabolism consisting entirely of peptides catalyzing the synthesis of one another, or one of RNA-like nucleic acids catalyzing the synthesis of one another. They could even have arisen independently and teamed up somewhere along the line. But it seems certain that the modern mechanism of protein synthesis based upon DNA code is a relatively late addition.

Well put Greg at March 1, 2007 03:19 PM

ca va

Let's see...

Chirality came first, probably with an assist from mineral surfaces. Most people think that there were at least a few intermediate steps and then self-replicating RNA (ribozymes) formed.

Proteins came along much later and sped up the process.

The switch from RNA to DNA as a genetic material was much later, but was probably "pushed" by parasitic RNA elements similar to present-day viruses. Switching to DNA provided better chemical stability AND allowed organisms to develop RNases to degrade the parasitic elements.

How's that? Will I roast in Hell for that?

Prometheus

You know, I actually used to like that Keith Green song, back in my evangelical days. Of course, even then I wasn't stupid enough to fall for this particular style of apologetics.