Discussion of all aspects of biological molecules, biochemical processes and laboratory procedures in the field.
The second question seems to be the same as the first one expressed differently, and if so then there's a last question that would be a second one and not a third one. Supposing it's only two questions, the answer to the first one would have to be "yes", and if I understand the other one then maybe the answer would be something like this: if you're a materialist, it's obvious for you that life first appeared in the course of certain chemical interactions and that all the manifestations of life are explainable through mere chemical ditto, but if you believe in immaterial phenomena it will be obvious for you that an Invisible Presence is running the show and that nothing happens by chance, so that the entire Universe is a deliberate, artificial creation, which means that nothing is "natural", meaning "spontaneous". Everything just SEEMS to be so, because the Presence must hide in a free-will Universe in order for reasoning creatures to be able to choose to believe or not to believe in Its Existence. Otherwise it wouldn't be a free-will Universe, the Ultimate Explanation would be inescapable and there would be no disagreement regarding that matter. I'm afraid I might've misunderstood the questions.
The answer to the first one is straightforward. In the Beginning there was the Haldane-Oparin thesis, but Haldane and Oparin freely and spontaneously disagreed as to the initial conditions necessary for the appearance of life. Eventually Urey worded the thesis differently and along with Miller he started to make experiments in a lab. They placed in a glass container what seems to have been the primordial atmosphere, they let sparks fly in it and they managed to synthesize several compounds that you need in order to create life. The conclusion was that lightning had done the same thing in the primitive Earth.
I come back here six days later and now I no longer understand my own first sentence. It's like a tongue twister. At least I can console myself by seeing how your own second question sent on Feb. 5 is just as incomprehensible. It seems to be the first question all over again followed by another one.
Why not start once again. "Are there any theories on etc.?" Yes. "Is it true that we don't know etc.?" We still don't, but several convincing chemical pathways have been shown to be plausible. They're discussing now what came first: the cell or the mitochondria (chemical factories) it harbors. Maybe a mitochondrion was first, then there were more and they got together loosely and founded a sort of colony and eventually some of them created the first cell.
I've heard about the "primordial soup", but it's the first time I see someone calling it the "ur-soup". Is this an allusion to the city Ur of the Chaldeans??? I'm guessing wildly. Sorry.
The "Invisible Presence" would be the Unknown God, as in the following quote: "And though as I walked upon your floors I saw many statues to many gods and I found this one, one that said 'TO AN UNKNOWN GOD!!!!!!!!!!!!!!!' " "Immaterial" or "incorporeal" things are things like apparitions, made up of stuff that is too "subtle" or "ethereal" to be perceived by the conventional senses.
For example, you're falling asleep and all of a sudden you find that you can see through your eyelids, then you find yourself up against the ceiling, in a corner of your room, like a balloon, and you see your own body lying there, and then several things can happen, like going out on the street and floating around until you reach the corner. You can go into a panic and this makes you go back instantly and "wake up". Actually you were wide awake, but in another, "immaterial" realm. It can be either spontaneous or deliberate since there are many ways to make it happen, but it's dangerous if you're a newbie.
A neurologist at the University of Amsterdam has recently learned how to, by stimulating a certain part of the brain, but he's a materialist and he thinks it's merely an electrically induced fantasy, not a gateway to the Beyond. He also has a scientific explanation for seeing "the light at the end of the tunnel", but not, as far as I know, for walking out of the tunnel and onto a prairie. This other explanation of his has to do with "tunnel vision" due to a lack of blood circulation in the eye. The Dutch doctor thinks he has all the answers, but he's still groping in the dark.
piscilactovegetarian: You wrote: «They're discussing now what came first: the cell or the mitochondria (chemical factories) it harbors. Maybe a mitochondrion was first, then there were more and they got together loosely and founded a sort of colony and eventually some of them created the first cell.» I am wondering, what kind of chemical processes do they suggest could have made the first cell or mitochondria?
Before the first cell there must've been a far simpler structure isolated from its environment by a primitive boundary, but what led to this was not any entirely chemical process but "physical chemistry", a rearrangement of elements involving both chemical and merely physical interactions, as in the formation of "colloidal" droplets in water where polymers (complex molecules) are dissolved that can be seen in laboratories.
Before that happened, there had to be the kind of monomers (simple molecules) that earthly life needs and that electric discharges in the atmosphere (lightning) helped to put together (also UV radiation, radiation issuing from radioactive elements in exposed rocks and shock waves caused by lightning and meteors, but to a much lesser extent).
Monomers started to come together and assemble polymers. These were 1) nucleic acids, which now both carry and pass on hereditary information, and 2) proteins, which can be either a) structural elements (building blocks for organic tissue) or b) enzymes (biocatalysts). An example of this would be the synthesis of the amino acid serine in the primitive atmosphere, thus: two molecules of formaldehyde condense to form glycoaldehyde, which Strecker synthesis could have converted into serine using glycoaldehyde, hydrogen cyanide and water. Serine has a hydroxyl group in its side chain.
There are lab models that show how monomers make polymers but no models showing how the genetic machinery could have developed.
The first creatures were bacteria (that's the plural, the singular being "bacterium"). They are prokaryotic cells (they lack a nucleus). This type of simpler cell has no mitochondria (plural [singular: "mitochondrion"]). Then came the eucharyotic cells (nucleus-bearing cells), which do have them. I seem to remember having read something about mitochondria having appeared before they were engulfed by a cell but I haven't been able to find the source. If it's true, then I guess it was a bacterium that did this, thus taking a big step on the way to becoming the first eukaryotic cell, so bacteria and mitochondria must've developed independently and side by side before coming together.
(Coincidentally, enzymes are mentioned in one of my lists of exceptional cases at http://excepciones-zoologicas.blogspot.com, a bilingual website: in animals the ONLY biochemical reactions that don't involve enzymes are spontaneous degradation reactions. It's in the third list ["Physiology"], which I haven't uploaded yet. Actually this is a general rule since it also holds true for creatures other than animals. I've already told about that website here, in two zoology discussions, because it will be useful for people who want to study Biology as a career.)
Thanks, piscilactovegetarian. You wrote: «Before the first cell there must've been a far simpler structure isolated from its environment by a primitive boundary, but what led to this was not any entirely chemical process but "physical chemistry", a rearrangement of elements involving both chemical and merely physical interactions, as in the formation of "colloidal" droplets in water where polymers (complex molecules) are dissolved that can be seen in laboratories.» I'll have to understand the first section of what you wrote first, so I'm wondering what you mean by: «primitive boundary» and «"colloidal" droplets in water» that are «,dissolved» and «seen in laboratories». Thanks a lot
The "primitive boundary" is simply the limit beteween the tiny droplet, globule, globulet, sphere or quasisphere and its surroundings. Those globules are colloidal, meaning that they're the kind of mixture called a "colloid", which is halfway between a homogeneous and a heterogeneous mixture, as explained in elementary chemical textbooks. In a colloidal solution the dissolved particles are larger than those in a true solution.
The concentration of dissolved polymers in the globulets is higher than in the surrounding watery environment. In lab experiments they can create such globules, which are not really the ancestors of the cell , but they show the complex chemical interactions that could've led to the formation of the first cell.
More about the mitochondria: there are two theories about their presence in cells. One of them says that the first host that "swallowed" one was a eukaryotic cell, the other one says that the host was a bacterium, in other words, a prokaryotic cell. I'm not really sure about the idea that motochondria were developed inside a cell rather than being initially like very simple cells that were swallowed by a far more complex cell. Either I read about this somewhere or I remembered vaguely something I read and then I made up the idea. Anyway, it looks like now everybody assumes that all mitochondria were once free agents.
They also say now that chloroplasts, too, were pre-existing, free-swimming creatures that ended up inside cells as "endosymbionts".
The discovery of the difference between pro- and eukaryotic cells is relatively recent and was made possible when the electronic microscope was developed and it was seen that bacteria have no nucleus and that all other kinds of cells do have one. This changed the way in which creatures are classified. The big difference was not really between "plants" and "animals" but between cells with no nucleus and cells with a nucleus. When I was in school all creatures were either plants or animals (and some, like "Euglena", seemed to be both, or halfway in between), so there were only two kingdoms of creatures: the Plant and the Animal Kingdoms (and there were three kingdoms in Nature, the other one being the Mineral Kingdom). Shortly after I graduated from high school in 1969, biologist Lynn Margulis's five-kingdom system replaced the two-kingdom system. Now algae and fungi are no longer "plants". The five kingdoms: Animal, Plant, Fungi, Protoctista (algae and slime molds, and not to be confused with the kingdom Protista suggested by Haeckel in the 19th Century), and Monera (bacteria). The first four are all prokaryotes. Bacteria are now seen as special creatures, unlike all others. (Maybe they're extraterrestrials, placed on Earth by those who travel back and forth in flying saucers and take some people for a ride???)
This complicated things greatly for me when I started to make my lists of zoological exceptions, so in order to simplify I chose to keep using the two-kingdom system, as explained in the Foreword. In my world, bacteria are still animals (and fungi and algae, still plants). Half a century ago everything, and not just the way Nature was classified, was simpler.
J. Bean, how many people know that now there are five kingdoms and no longer just two? The lists of zoological exceptions are an amateur's project for the billions, not for the tiny professional minority, so simplifying the classification of life forms was far more adequate. Even so, 1) I doubt that most individuals belonging to that minority are aware of most of the nearly one thousand cases I've gathered so far and consequently they could find the lists useful, and 2) I am no more of a simplifier than BioLib, where they seem to believe that Nature offers only minerals, fungi, plants and animals, or they care less or not at all about the two groups that are missing in their records, which is quite unfair for professionals to do.
Please tell them that eventually I will add a much shorter list of botanical exceptions and would appreciate their reporting on additional examples, both zoological and botanical, as per the two-kingdom system. Also, will you please ask them what ever happened to "socialism with a human face"? "Savage capitalism" is now everywhere and getting rid of the "useless eaters" as though they were algae, slime molds and bacteria. Even ex-KGB Lieut. Col. V. Putin is playing that infamous game now. Hail Pussy Riot!!! I thank you in advance.
The aforementioned neurologist at the U. of Amsterdam is Dick Swaab, MD. His case is not unusual: in Northern Europe, when asked, 70 % of the people claim to be atheists.
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