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Difference between the Bacteria and the Archaea

  1. Jan 13, 2017 #1

    ShayanJ

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    I don't know much about biology but the origin of life has always been very interesting to me so I sometimes check to see whether there was any progress or not. Now this recent development seems so important but I don't quite understand it because I don't know the difference between the Bacteria and the Archaea. Can anyone explain this to me?
    I know almost nothing about biology so I appreciate it if you could keep it simple. But I also enjoy learning a lot in a little time so I also appreciate it if you can explain as much as you can in your reply even if it goes off-topic.
    Thanks
     
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  3. Jan 13, 2017 #2
  4. Jan 13, 2017 #3

    Bystander

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  5. Jan 13, 2017 #4
    Thanks for the license to go off-topic...:oldsmile:

    I won't bore you with the details (or will I?o_O), but let's just say that at 23 years of age I found myself at a crossroads..What was I going to devote my life's studies to? After some thought I distilled it down into three categories:

    1) How the evolution of the brain produced the human condition whereby we had these mammals that could talk and think and be self-aware, i.e., the appearance of consciousness

    2) The grand unified theory (you know) of physics and the big bang, and

    3) The origin of life

    After some deliberative thought on the subject over Micky's malt liquor's 40 oz in the early 90's I eventually picked number one. Why? Because,

    1) As far as the GUT, I didn't think you could solve the bigger origin problems of physics without understanding how the brain worked because the instrument you are using to study the universe is the brain. So I thought that trying to make some assertions as to how the external physical world worked without knowing how your brain worked was the equivalent of trying to weighing a mass without calibrating your scale. So what's the point?

    2) As far as the origin of life, I thought it was going to be an effort of exploration and field research, neither of which appealed much to me. I'm a pencil and paper theoretician kind of guy.

    That said, at the time I was 23 each of these three "origins tales," if you will, were equally important to me. In fact, I remember actually weighing in most heavily on the origin of life quest initially before I came to the realization that it was a mostly untenable career path, unless you fancied yourself a martyr.

    Even so, to cover my bases, I chose to pick "General Biology" as my major. That kind of covers all three. You've got to take the math and physics for the Bio requirements even though biology is a "soft science." That's all good. But you've also got the molecular biology and the brain physiology requirements to cover the other two origin stories. So that's what I did.

    Why am I telling you this? I think my story is instructive in that I think understanding how life evolved on Earth is equally important as the big physics an the big neuro quests, but you don't hear much about the "origin of life" quest much relative to the other two.

    So maybe this Nature article does turn out to be something, but just as the other two origin stories, it probably will be mired in controversy. As far as the origin of life is concerned, I'm not so much interested in the descent of eukaryotes from prokaryotes as much as I'm concerned about the more fundamental appearance of the prokaryotes in the first place.

    Btw, it was only later in my life that I came to more of an understanding as to why I had this epiphany that science was going to be my pursuit. Before that, I was a happy, (somewhat) healthy, content beach bum in Hawaii having a great time. I didn't ask for the curse (as Neil Turok phrased it) of wanting to solve the world's origin problems. As an added note, it was only a few years ago that I found out through research that there's a rostro-caudal tract of brain development from the frontal to occipital lobe that only matures at approx. 23 years of age. Knowing what I know about the brain, it makes sense that I would have these epiphanies at this time, as many other scientists seem to have. If anyone's interested in me digging up a study on the topic, let me know.
     
  6. Jan 13, 2017 #5

    BillTre

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    Very interesting question @ShayanJ!
    Since I didn't know a lot about these differences, I did some research.
    I hope this is interesting, but not too detailed for you.

    Previously I had known:

    1) Bacteria and archea are "different" (meaning there were two groups that evolved separately from some common ancestor).
    Who came first or was there a separate precursor that both groups can from, I don't know.
    2) Many archea are extremophiles (like, or are able to, live in extreme environments, like high temperatures and unusual chemical environments).

    After reading a wikipedia article and finding a summary diagram, I can add the following information:
    Membranes:
    3) The archeal cell walls differ from bacteria in that they (like eukaryotes) lack peptidoglycan.
    4) Archeal cell membranes contain some branched hyrdocarbons instead of the unbranched hydrocarbons of eukaryotes and bacterial.
    5) The lipids of the membrane molecules are joined the phosphate heads by ether links rather than ester linked (considered more stable at high temperature)
    6) Some Archeal membranes have the lipids of the two layers of the membrane (outside and inside) fused end to end to make an single (2x long) membrane molecule with two hydrophilic ends.

    These membrane differences may originated from the need for greater stability at high temperatures.

    Genetic mechanisms:
    7) Bacteria have only one RNA polymerase (enzyme that copies RNA), Archea and Eukaryotes have more than one RNA polymerase.
    8) Bacteria use a formyl-methionine as a first amino-acid in a protein, while Archea and Eukaryotes use methionine.
    9) Bacteria have few introns, Archea have more, and eukaryotes have lots. Introns are bits of sequence that are copied from DNA to RNA, but are then cut out, before the sequences is translated into protein (by the ribosomes, by stringing together amino acids).
    10) Antibiotics affecting bacterial ribosomes don't affect archeal or eukaryotic ribosomes (where proteins are made).
    11) Apparently some Archea have some histones (DNA structural packing/support proteins important to Eukaryotes). Bacteria do not.
    12) Both Bacteria and Archea have circular chromosomes, while Eukaryotes have much larger linear chromosomes (which require a different and complex mechanisms to properly control them during cell divisions). Eukaryotes also have circular chromosomes, but only in things like mitochondria or chloroplasts which are considered remnants of bacteria which became symbionts.

    Cell Biology:
    Interestingly, the Asgardians (the new group of Archea, thought ancestral to Eukaryotes) have more cytoskeletal proteins (making them more like Eukaryotes) and some proteins involve in membrane functions (also more like Eukaryotes).
    It would be very interesting to see what they look like (in an electron microscope) to see their size, internal complexity as well as what their membranes are doing. Eukaryotes have a lot of different parts of the their cells which cytoskeleton and membrane movements are involved in.
     
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