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  1. #1
    Join Date
    Jan 2012

    The Simplest Cell

    While we have a breather in the thread; 'What's The Best Evidence For Evolution', I thought I would look at some information on living cells. Human cells are very complicated and plant cells are compliacated too. So I thought I would do a search for information on the simplest cell. We can all do the same these days and find out what webpages Google has referenced. On the first page of Google I came across two articles. The first article is from Science Week and the second is from a website created by Adolfo Serralta connected with the Bible. I do not know if Adolfo Serralta wrote this article or whether it has been donated, but it illustrates the difficulties which are apparent in the article from Scientific Week.

    Evolution is based on all life/living matter originating from the simplest of cells. It is difficult to make a simple cell in the laboratory or for a simple cell to form on its own. Nature shows us many plants and insects etc. that have to produce lots of seeds and eggs for one to survive and grow. It makes sense that there has to be an environment conducive for the chemicals/materials to come together and combine to form lots of partial cells and eventually to produce complete cells for one or two complete cells to begin the process of dividing and multiplying. Everything about the processes involved with cell production is highly complicated as these two articles convey. I present the two articles to provide a balanced presentation; one from a scientific source and the second from a non-scientific source. The Science Week article is from the year 2005 so advances can be expected. If anyone has some later research as evidence to support the case for Evolution, then that is welcomed.



    The following points are made by Eörs Szathmary (Nature 2005 433:469):

    1) In investigating the origin of life and the simplest possible life forms, one needs to enquire about the composition and working of a minimal cell that has some form of metabolism, genetic replication from a template, and boundary (membrane) production.

    2) Identifying the necessary and sufficient features of life has a long tradition in theoretical biology. But living systems are products of evolution, and an answer in very general terms, even if possible, is likely to remain purely phenomenological. Going deeper into mechanisms means having to account for the organization of various processes, and such organization has been realized in several different ways by evolution. Eukaryotic cells (such as those from which we are made) are much more complicated than prokaryotes (such as bacteria), and eukaryotes harbor organelles that were once free-living bacteria. A further complication is that multicellular organisms consist of building blocks -- cells -- that are also alive. So aiming for a general model of all kinds of living beings would be fruitless; instead, such models have to be tied to particular levels of biological organization.

    3) Basically, there are two approaches to the "minimal cell": the top-down and the bottom-up. The top-down approach aims at simplifying existing small organisms, possibly arriving at a minimal genome. Some research to this end takes Buchnera, a symbiotic bacterium that lives inside aphids, as a rewarding example. This analysis is complemented by an investigation of the duplication and divergence of genes. Remarkably, these approaches converged on the conclusion that genes dealing with RNA biosynthesis are absolutely indispensable in this framework. This may be linked to the idea of life's origins in an "RNA world", although such an inference is far from immediate.

    4) Top-down approaches seem to point to a minimum genome size of slightly more than 200 genes. Care should be taken, however, in blindly accepting such a figure. For example, although some gene set A and gene set B may not be common to all bacteria, that does not mean that (A and B) are dispensable. It may well mean that A or B is essential, because the cell has to solve a problem by using either A or B. Only experiments can have the final word on these issues.

    5) A top-down approach will not take us quite to the bottom, to the minimal possible cells in chemical terms. All putative cells, however small, will have a genetic code and a means of transcribing and translating that code. Given the complexity of this system, it is difficult to believe, either logically or historically, that the simplest living chemical system could have had these components.

    6) The bottom-up approach aims at constructing artificial chemical supersystems that could be considered alive. No such experimental system exists yet; at least one component is always missing. Metabolism seems to be the stepchild in the family: what most researchers in the field used to call metabolism is usually a trivial outcome of the fact that both template replication and membrane growth need some material input. This input is usually simplified to a conversion reaction from precursors to products.



    Related Material:


    The following points are made by S. Rasmussen et al (Science 2004 303:963):

    1) All life forms are composed of molecules that are not themselves alive. But in what ways do living and nonliving matter differ? How could a primitive life form arise from a collection of nonliving molecules? The transition from nonliving to living matter is usually raised in the context of the origin of life. But some researchers(1) have recently taken a broader view and asked how simple life forms could be synthesized in the laboratory. The resulting artificial cells (sometimes called protocells) might be quite different from any extant or extinct form of life, perhaps orders of magnitude smaller than the smallest bacterium, and their synthesis need not recapitulate life's actual origins. A number of complementary studies have been steadily progressing toward the chemical construction of artificial cells (2-5).

    2) There are two approaches to synthesizing artificial cells. The top-down approach aims to create them by simplifying and genetically reprogramming existing cells with simple genomes. The more general and more challenging bottom-up approach aims to assemble artificial cells from scratch using nonliving organic and inorganic materials.

    3) Although the definition of life is notoriously controversial, there is general agreement that a localized molecular assemblage should be considered alive if it continually regenerates itself, replicates itself, and is capable of evolving. Regeneration and replication involve transforming molecules and energy from the environment into cellular aggregations, and evolution requires heritable variation in cellular processes. The current consensus is that the simplest way to achieve these characteristics is to house informational polymers (such as DNA and RNA) and a metabolic system that chemically regulates and regenerates cellular components within a physical container (such as a lipid vesicle).

    4) Two recent workshops(1) reviewed the state of the art in artificial cell research, much of which focuses on self-replicating lipid vesicles. David Deamer (Univ. of California, Santa Cruz) and Pier Luigi Luisi (ETH Zurich) each described the production of lipids using light energy, and the template-directed self-replication of RNA within a lipid vesicle. In addition, Luisi demonstrated the polymerization of amino acids into proteins on the vesicle surface, which acts as a catalyst for the polymerization process. The principal hurdle remains the synthesis of efficient RNA replicases and related enzymes entirely within an artificial cell. Martin Hanczyc (Harvard Univ.) showed how the formation of lipid vesicles can be catalyzed by encapsulated clay particles with RNA adsorbed on their surfaces. This suggests that encapsulated clay could catalyze both the formation of lipid vesicles and the polymerization of RNA.



    The following points are made by M.M. Hanczyc et al (Science 2003 302:618):

    1) The bilayer membranes that surround all present-day cells and act as boundaries are thought to have originated in the spontaneous self-assembly of amphiphilic molecules into membrane vesicles (1-5). Simple amphiphilic molecules have been found in meteorites and have been generated under a wide variety of conditions in the laboratory, ranging from simulated ultraviolet irradiation of interstellar ice particles to hydrothermal processing under simulated early Earth conditions.

    2) Molecules such as simple fatty acids can form membranes when the pH is close to the pK[sub-a] (K[sub-a] is the acid dissociation equilibrium constant) of the fatty acid carboxylate group in the membrane (3). Hydrogen bonding between protonated and ionized carboxylates may confer some of the properties of more complex lipids with two acyl chains, thus allowing the formation of a stable bilayer phase. Fatty acid vesicles may be further stabilized (to a wider range of pH and even to the presence of divalent cations) by the admixture of other simple amphiphiles such as fatty alcohols and fatty acid glycerol esters. Recent studies have shown that saturated fatty acid/fatty alcohol mixtures with carbon chain lengths as short as 9 can form vesicles capable of retaining ionic fluorescent dyes, DNA, and proteins (4).

    3) Vesicles consisting of simple amphiphilic molecules could have existed under plausible prebiotic conditions on the early Earth, where they may have produced distinct chemical micro-environments that could retain and protect primitive oligonucleotides while potentially allowing small molecules such as activated mononucleotides to diffuse in and out of the vesicle. Furthermore, compartmentalization of replicating nucleic acids (or some other form of localization) is required to enable Darwinian evolution by preventing the random mixing of genetic polymers, thus coupling genotype and phenotype. If primordial nucleic acids assembled on mineral surfaces, the question arises as to how they eventually came to reside within membrane vesicles. Although dissociation from the mineral surface followed by encapsulation within newly forming vesicles (perhaps in a different location under different environmental conditions) is certainly a possibility, a direct route would be more satisfying and perhaps more efficient.

    4) In summary: The clay montmorillonite is known to catalyze the polymerization of RNA from activated ribonucleotides. The authors report that montmorillonite accelerates the spontaneous conversion of fatty acid micelles into vesicles. Clay particles often become encapsulated in these vesicles, thus providing a pathway for the prebiotic encapsulation of catalytically active surfaces within membrane vesicles. In addition, RNA adsorbed to clay can be encapsulated within vesicles. Once formed, such vesicles can grow by incorporating fatty acid supplied as micelles and can divide without dilution of their contents by extrusion through small pores. These processes mediate vesicle replication through cycles of growth and division. The authors suggest the formation, growth, and division of the earliest cells may have occurred in response to similar interactions with mineral particles and inputs of material and energy.

    Inorganic matter could have never evolved into a so called "
    first simplest cell"

    I advise that this article should be given to our young college group
    in an effort to help them avoid being misinformed by pseudo science.  Our young adults environment was and will be bombarded with false information.  It is important to prepare the college group in an effort to prevent a set back in their faith.

    There are only two alternatives to explain the existence of living beings:
    one is the theory of Creation and the other is the hypothesis of spontaneous generation. The hypothesis of evolution is just a new name given to the spontaneous generation after it was discredited and proved unscientific by Pasteur's experiments. Don't let anyone fool you by the new names. No matter if it is called evolution, mutation, or whatever, what does not belong to the theory of Creation, belongs to the hypothesis of spontaneous generation.

    The evolution hypothesis
    is based on the supposition that once upon a time the "first simplest cell" popped up from the sea and that the planet was a vast sphere of only inorganic products, until the so called "first simplest cell" appeared. After its appearance, according with the mentioned hypothesis, this cell started to live, procreate, and evolve towards more and more complex living entities. Of course, those who believe this hypothesis never bother themselves in explaining how the inorganic matter could organize itself into organic matter. To "explain" it they pass the bucket over to their god; they just put their faith in their god: "TIME". According to their faith, millions and millions of years can organize matter and do the same job that we Christians know God our Creator did. They do not explain how time can do the job; they just dogmatically affirm their god TIME can.

    According to the evolution hypothesis
    during millions of years water had only inorganic matters in its solution till one day, by some hocus-pocus act that cannot be explained nor proved, appeared the simplest living organism: the so called "first simplest cell". This cell was the first step in a huge evolution staircase of millions of steps, which led up to human beings. If complexity went a step down from this "first simplest cell", it would become just inorganic matter; but if complexity went one step up from inorganic matter it would become the "first simplest cell". According to evolutionists, this "first simplest cell" lived for a while feeding itself from the environment, and reproducing itself, so as to bring to existence other cells just as itself. As this process continued for millions of years, the Earth was populated by cells that evolved into more complex vegetation and animals.

    Can this hypothesis be substantiated, proved, or at least explained logically? Does it have no scientific or logical flaws? This is not a real scientific hypothesis because it has nothing to prove and there are several logical and scientific arguments to disprove it. It is just an act of faith by those who do not want to recognize that a Creator exists. Let us reason together using logics and our common sense, because this evolution hypothesis is out of all reason.

    The so called "first cell" also called the "simplest cell", could have never existed. Why not? Let's see first what the "simplest cell" had to have in order to perform the jobs assigned to it: to live,
    grow and reproduce.

    First. The "first simplest cell" had to have a membrane, otherwise it was just part of the environment. In order for the cell not to be part of the environment, there had to exist a separating factor or membrane. Until not very long ago the membrane was not well known. Today we have discovered so many functions in it that there is a whole subject of study about the membrane. Even a scientific publication named "Journal of Membrane" exist, because of the complexity of the membrane and a whole lot that is needs to be learned about it. So, the "first simplest cell" had to have a very complex membrane, that had to allow food to go through but not let the inside matter get out.

    In order for the "first simplest cell" to keep living after popping up out of the environment, it had to have the possibility of taking inorganic matter from the environment, introduce
    it in its body, and process it so as to break it into less complex inorganic matter. This would have to be done in order to get the vital energy resulting from the breaking process, so that the cell could be alive. This process is what we call digestion, performed by the stomach, or better said, by the digesting apparatus. To break inorganic matter and get the energy resulting, is a complicated process that requires lots of knowledge about what chemical products will break other ones. It is not a simple thing. So, the so called "first simplest cell" had to have a very complex digesting apparatus.

    Since this "first simplest cell" had to reproduce itself, it had to have a reproductive system. This reproductive system had to be skilled enough to know what would be the
    right time for reproduction,
    because the cell cannot reproduce unless it has enough matter for itself, so as not to die in donating its own matter to the other cell.

    This "first simplest cell" had to have some ADN kind of thing, otherwise it wouldn't transmit to its descendants the necessary apparatuses to keep living, feeding and reproducing. Until some decades ago we did not know how complex the AND was. Now, that we have that knowledge we have to agree that any kind of chemical code that transmits characteristics from one cell to another is highly complex. This high complexity had to be present in the so called "first simplest cell". It is a nonsense to think that the so called first simplest cell could have ever existed.

    Because the cell had inside itself other apparatuses apart from the stomach, and because those apparatuses need to be fed, then the so called "first simplest cell" needed a distribution
    system to carry the food from the stomach to other parts of the cell. This means that it had to have some sort of a simple distribution system.

    The fact of having all these apparatuses brings forth another need. The "first simplest cell" had to have an apparatus to coordinate the works of the other ones. If not, an apparatus could be working or not working as it is necessary for the cell in order to live and reproduce. This means that the cell had to have a coordinating apparatus, sort of a central nervous system.

    As we can see this so called "first simplest cell" never could have been that simple, but instead highly complex, because in order to live and reproduce, it had to have many complex apparatuses. Each apparatus itself was complex enough as to not be deemed to pop up out of nothing. Much less can it be admissible to deem that all of them popped up together, in the same place, at the same time, joined together, coordinated themselves, and covered themselves with a working membrane to become a biological entity.

    As I said in the title of this article:
    Inorganic matter could never have evolved into a "first simplest cell".
    Last edited by David M; 07-04-2012 at 04:45 PM.

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