How does the theory of evolution reconcile the fact that proteins are required to make proteins? How did amino acids originally come together to form the first proteins? I understand that amino acids can be made through random chance, but how do those amino acids specifically line up with strands of RNA in order assemble into proteins? Any molecular biologists out there? (Please no biblical references
I’m not a biologist so I can’t answer your question in great detail, but I am an annoying nitpicker, and I see a technical nit I can here pick.
What you are talking about is not Evolution per se, but Abiogenisis. Abiogenisis deals with the problem of how life got started in the first place, while evolution deals with the trasformation of one species into another and the growth and spread of life.
Also the clearest account of Abiogenisis I have read is in John Casti’s paradigms lost, but the book was published in 1988, and is probably out of date.
Sorry this doesn’t answer your question, hopefully someone more equipped will come this way.
Perked Ears indicate curiosity - Know Your Cat
Related point: under laboratory conditions, including electrical discharge through HCN containing vapours, at least traces of the purine bases have been detected.
Also, remember that the secondary, tertiary and quaternary structures of proteins can come about through self-assembly.
Hi Matt MacKinnon, I know if you are a student your budget is probably books and beer but you probably also have access to the local used text book store and can find a good general biology there along with several others in use for more advanced biology. They are almost a steal compared to band new.
Even Larry B’s suggestion: “John Casti’s paradigms lost, but the book was published in 1988, and is probably out of date.” is not a lost cause. Places like Powell’s at www.powells.com (could have one l and no s or s and no l or two lls and no s!!) have used books, too. Reasonable and quick service.
You’ll get reasonable information with out much fuss - and then have a good basis for asking questions.
Are you driving with your eyes open or are you using The Force? - A. Foley
Take the above experiment and keep it going for a few milloin years on a larg scale (like Earth) and you would get the protiens.
Jois,
As a former manager of a Used Book store with a nationwide search service, I would always recommend them for hard to find books.
My point was that there have probably been advances in thought since Casti published his books.
Amazon is still listing:
Paradigms Lost : Tackling the Unanswered Mysteries of Modern Science
by John L. Casti. Paperback (November 1990)
Our Price:$11.20
You Save: $2.80 (20%)
Usually ships in 24 hours
Tom~
Good find Tom, I usually try Powell’s first, habit, I guess.
I don’t mind the pub. date of Casti’s book. If he provides a good explanation and gets you adjusted to the vocabulary, you can find the newest information/arguments on line or even on this board
Larry.
Are you driving with your eyes open or are you using The Force? - A. Foley
I prefer abebooks.com to amazon any day. Quicker and cheaper. For instance, there are at least a dozen copies of Paradigms Lost… on ABE for $15.00 or less – I saw several under $8.00. Not counting shipping, of course.
Jess
Remember the Straight Dope credo: It’s all about wiping out ignorance, not coddling the ignorant.
Actually, the question was brought up by my roommate, who is taking biology at university. He makes a good point. In an evolutionary (or abiogenetic) sense, where does DNA come from? How do these highly complex organizations of chemicals form in the first place? If you have a bunch of amino acids floating in some primordial ooze, how do they get together and make a cell? From what I can gather, I don’t think this is addressed in most text books.
The answer is simple…
Time.
Even the most unlikely of things can happen when given enough time.
Keep in mind that we’re talking on a scale of billions of years here.
The answer is simple…
Time.
Even the most unlikely of things can happen when given enough time.
Keep in mind that we’re talking on a scale of billions of years here.
“All men spoke of his prowess…except for a couple of people in his home village who though he was a liar, and quite a lot of other people who had never really heard of him.” -Terry Prachett - The Light Fantastic
This is the most common problem that people have with evolution, they cannot imagine events on that long a time scale. Don’t forget that once one self replicating system develops, no matter how simple, it has an enormous “survival advantage”.
This question has been tackled quite extensively, even at textbook level. Gosh, even Carl Sagan had a crack at it.
Me neither ;).
Time and natural selection. As I have shown earlier, even a trivial natural selection process can remove as many as 60+ orders of magnitude from a combinatorial task.
Has anyone here heard of ribosymes? They are strands of RNA (the bases of which, as has been previously mentioned, become assembled spontaneously from the primordeal soup) with the capability to replicate themselves. all that is needed is just one of these structures fromed from a random collection of bases combining in the right order (and it seems this must have occurred eventually, as there was an entire ocean full of 10^(to the god knows how many powers) atoms and molecules of ingredients and a billion years in which to do it). after that, the fact that these suckers could self-replicate and other molecules could not would give them a huge advantage and the oceans would soon be full of them. Add a cell membrane (which are also largely self-assembling) and you’ve got yourself a proto-cell. now just add another three billion years of evolution, and here we are!
Let me preface this by saying it’s been a good ten years since I had molecular biology, but if N-terminus is positively charged for most (or all?) amino acids and the C-terminus negatively charged, all things being equal, won’t the amino acids be attracted to one another by charge alone?
Regarding the origin of DNA and life…my personal feeling is that it likely happened in reverse:
- amino acids + energy = proteins
- proteins + other proteins (enzymes) = RNA and viruses
- RNA and viruses + other proteins (like a reverse transcriptase) = DNA
- Add protein coat and let simmer for several million to billion years…adding a touch of natural selection for flavor
- Evolve bacteria
- repeat step four to get your multi-cellular organisms and go from there.
I’m sure I’m missing some pages from the cook book, but that’s my basic guess
Sorry, but this answer doesn’t cut it. If abiogenesis occurred (and I’m not arguing one way or another at this point), it more likely occurred due to environmental factors that generated structure where there was none. Time is possibly the answer to how that structure was able to evolve into the various life forms we find today and time addresses a part of the question of how probable is it that abiogenesis occured.
This is the most common problem with most evolution advocates, while they seem to be able to grasp the expanse of time involved, they completely underestimate the complexity of the system and the probabilities involved.
For abiogenesis to be valid we have to assume that, first, the 20 (alpha) amino acids found in proteins formed as a natural course of inorganic chemistry. So far, in laboratory environment, we’ve only been able to generate a handful of these amino acids without the benefit of organic materials to synthesize from. If we struggle to do it in a lab, what are the probabilities that it happened accidentally? … but let’s assume that, nevertheless, the universe overcame these odds and produced the necessary amino acids in a suitable environment. Now these amino acids must group to form peptides. Again, we have not seen peptide formation to be a naturally occuring chemical event, so the (im)probabilities go up. But we’re talking about eons here, so let’s assume that nature overcame these odds, as well. Now for abiogenesis to take place, at the very least (some scientists claim this is overly optomistic), lots of these peptides must be laying around, combining and recombining to eventually form an RNA chain. Again, even using peptides synthesized from organic material, we’ve yet to form RNA in a lab, so we seem to still be dealing with astronomical odds. But let’s say even this happens, is this life? Well, this is where some of the experts start to diverge. Some think that, once you have abundant RNA material laying about, a virus-like organism could be born and from that a DNA structure could emerge. Others argue that viruses don’t replicate on their own, they need host DNA. Therefore, if you buy into this school of thought, you have to go that one step further and suppose that all of the peptides and nucleotides will come together to form a DNA strand - one that has the proper mechanics for self replication, by the way.
It’s all very complex and I’m sure I’ve butchered some of the facts a bit, but the point is still valid: There are a lot of intermediate low probability, non life steps that have to occur along the way to the emergence of your first real living organism. We have yet to demonstrate that many of these steps can even be accomplished in a laboratory, much less as a natural course of nature in the primordial soup of a primitive Earth.
In reference to the specific question asked in the OP:
The plain truth is, none of the theories of evolution or abigenesis can adequately reconcile this question… today.
BTW, my personal beliefs (so you’ll know my bias) are that it seems improbable that life, as we know it, randomly bubbled up from the primordial soup. The intricate and delicate detail that I see in living organisms suggest to me that life, as we know it, was the product of intelligent design. But designed by who? Well, by a life form, NOT as we know it… However, I’m ready to cast my little theory aside in favor of another, possibly abiogenetic one, if given enough demonstrable evidence of feasibility and probability.
Just had to comment on this one. There are millions of processes that happen everyday in nature that we have to struggle to recreate in a lab. There are many more that we can’t currently replicate. That is not a good argument.
And while we’re at it:
Since you seem so fond of arguing probabilities, perhaps you can actually supply some?
Without arguing one way or another about the nature of abiogenesis, I have little patience with arguments from probability that do not actually supply the odds that they consider to be so compelling. How is one supposed to evaluate your “astronomical odds” if you do supply both the numbers and the derivation of those numbers.
Or should we, perhaps, replace all references to probability in the above post with “JoeyBlades feels”?
The best lack all conviction
The worst are full of passionate intensity.
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