Home » Cell biology, News » How do cells suddenly create their little incinerators from scratch?

How do cells suddenly create their little incinerators from scratch?

File:Autophagy diagram PLoS Biology.jpg

autophagy in fruit fly larva/Neufeld, Scott, Nizushima

In “The Enigmatic Membrane” (The Scientist, February 1, 2012), Muriel Mari, Sharon A. Tooze, and Fulvio Reggiori report, “Despite years of research, the longstanding mystery of where the autophagosome gets its double lipid bilayers is not much clearer.” The autophagosome is a device inside a cell that chemically incinerates dead stuff, clutter and germs, producing fuel:

Cells live longer than their internal components. To keep their cytoplasm clear of excess or damaged organelles, as well as invading pathogens, or to feed themselves in time of nutrient deprivation, cells degrade these unwanted or potentially harmful structures, and produce needed food and fuel, using a process they have honed over millions of years. Known as autophagy, this catabolic process involves the selection and the sequestration of the targeted structures into unique transport vesicles called autophagosomes, which then deliver the contents to lysosomes where they are degraded by lytic enzymes. This conserved eukaryotic pathway plays a central role in a multitude of physiological processes, including programmed cell death, development, and differentiation.

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Despite significant advances over the last 20 years in the understanding of how this process works and what purposes it serves, there is a lingering question—how are autophagosomes formed? More specifically, where do their not one, but two lipid bilayers come from? Autophagosomes are not pre-built organelles that become active upon the induction of autophagy; they are made from scratch each time a cell needs to degrade one or more of its contents. And they are giant vesicles, with an average diameter of approximately 700–800 nanometers, which can further expand to accommodate large structures such as cellular organelles and bacteria, and which are made in large quantities under autophagy-inducing conditions. As a result, progression of autophagy requires a ready supply of lipids. This aspect of the process has intrigued researchers since the discovery of autophagy in the 1950s and ’60s. Understanding the biogenesis of autophagosomes will provide information about how cells generate new compartments in response to internal and external cues, and will thus lead to a clearer conception of cell homeostasis.

And much more.

The authors look at various possible sources of the essential membrane without much success. This looks like a promising area for design theorists. Especially because many diseases (“cardiovascular and autoimmune diseases, neuro- and myodegenerative disorders, and malignancies”) are linked to problems with cleaning up the cell. If we knew how the autophagosomes suddenly get made from scratch as needed, we might have a better idea how to make it happen more quickly or more often- when nature needs a nudge.

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14 Responses to How do cells suddenly create their little incinerators from scratch?

  1. using a process they have honed over millions of years

    Yet another meaningless phrase added at random to give the required obeisance to god of chance.

    I guess before this process was sufficiently honed cells just died faster.

    No doubt the researchers are, even now, nailing down the precise evolutionary sequence.

  2. Semi OT: A printer that prints complex 3-D parts;

    Mind Blowing Technology – video
    http://www.break.com/index/min.....gy-2300947

    OK Darwinists, is the machine a product of intelligent design or was it a product of random chance???

  3. Intelligent design.

    What are some things that are the product of random chance?

  4. lastyearon you state in answer to the question,

    Intelligent design.

    OK, I’ll play along, why is the machine intelligently designed and yet the engineer, who is vastly more complex than the machine, who intelligently designed the machine, not intelligently designed??? Exactly what criteria did you use to infer intelligent design of the machine???

  5. SCheesman, you have a wicked, wicked tongue. Each sentence is a gem.

    Any thought of putting in my two penn’orth vanished as soon as I began reading your post.

  6. Even the words, ‘nailing down the precise evolutionary sequence’ have a particularly ironic, hilariously ironic resonance for UDers. Lots of ‘probably’s, ‘must haves’ and ‘no doubt’s and ‘would have’s’. ‘Nail ‘em down’!!!

    Incidentally, I’ve always thought it curious that those folk-singers should think it worthy of mention that they’d prefer to be a hammer than a nail. I doubt if even masochists would want to be the nail. Also, incidentally, and by sheer random chance, I have finally contributed something technical to this forum – even if it was just a hammer and a nail.

    I think I must have been ‘in the zone’, conjecturing about evolution, when the inspiration crept up on me.

  7. Semi OT:

    On this episode of ID the Future, Casey Luskin interviews Dr. Donald E. Johnson about his 2010 book, Programming of Life, which compares the workings of biology to a computer.

    Programming of Life – podcast
    http://intelligentdesign.podom.....9_15-08_00

  8. Here is the video that goes with the ‘Programming Of Life’ book:

    Programming of Life – video
    http://www.youtube.com/watch?v.....F11E2FB840

  9. lastyearon @3:

    “What are some things that are the product of random chance?”

    The rocks strewn about my driveway, the leaves on the ground under the tree, the papers all over my desk and the floor. Oh, sure there is a non-random component in the sense that things are governed by the laws of physics. So we could have the age-old discussion about whether anything is truly random. Either way, it is in opposition to something that is designed, because the latter (i) has characteristics of design, and (ii) is not explainable solely by reference to chance and necessity.

  10. lastyearon; you may appreciate this quote as to how people ‘automatically’ infer intelligent design:

    ,,As obviously designed as a spaceship or a computer…Evolutionary biologists have been able to pretend to know how complex biological systems originated only because they treated them as black boxes. Now that biochemists have opened the black boxes and see what is inside, they know the Darwinian theory is just a story, not a scientific explanation… (Phillip E. Johnson, Defeating Darwinism, Downers Grove, IL: InterVarsity Press, 1997, 77-78.)
    http://www.classicalconversati.....atics.html

    Along that same line,,

    Michael Behe – Life Reeks Of Design – 2010 – video
    http://www.metacafe.com/watch/5066181

    On this episode of ID the Future, Casey Luskin interviews Dr. Donald E. Johnson about his 2010 book, Programming of Life, which compares the workings of biology to a computer.

    Programming of Life – February 2012 – podcast
    http://intelligentdesign.podom.....9_15-08_00

    Here is the video that goes with the ‘Programming Of Life’ book:

    Programming of Life – video
    http://www.youtube.com/watch?v.....F11E2FB840

  11. What are some things that are the product of random chance?

    The pattern of leaves on my lawn.

    The pattern of clouds in the sky.

    The dust bunnies behind my computer desk.

    The dust bunnies under my bed.

    The rust on my old snow blower.

    Sickle-celled anemia.

    Well those are some things but by no means everything.

  12. Perhaps people who ‘automatically’ see intelligent design in nature and in life are like the little children in this story who recognize something beautiful, as opposed to the adults in the story who are ‘too busy’ to recognize the treasure right before their eyes and ears::

    A man sat at a metro station in Washington DC and started to play the violin; it was a cold January morning. He played six Bach pieces for about 45 minutes. During that time, since it was rush hour, it was calculated that 1,100 people went through the station, most of them on their way to work.

    Three minutes went by, and a middle aged man noticed there was musician playing. He slowed his pace, and stopped for a few seconds, and then hurried up to meet his schedule.

    A minute later, the violinist received his first dollar tip: a woman threw the money in the till and without stopping, and continued to walk.

    A few minutes later, someone leaned against the wall to listen to him, but the man looked at his watch and started to walk again. Clearly he was late for work.

    The one who paid the most attention was a 3 year old boy. His mother tagged him along, hurried, but the kid stopped to look at the violinist. Finally, the mother pushed hard, and the child continued to walk, turning his head all the time. This action was repeated by several other children. All the parents, without exception, forced them to move on.

    In the 45 minutes the musician played, only 6 people stopped and stayed for a while. About 20 gave him money, but continued to walk their normal pace. He collected $32. When he finished playing and silence took over, no one noticed it. No one applauded, nor was there any recognition.

    No one knew this, but the violinist was Joshua Bell, one of the most talented musicians in the world. He had just played one of the most intricate pieces ever written, on a violin worth $3.5 million dollars.

    Two days before his playing in the subway, Joshua Bell sold out at a theater in Boston where the seats averaged $100.

    This is a real story. Joshua Bell playing incognito in the metro station was organized by the Washington Post as part of a social experiment about perception, taste, and priorities of people. The outlines were: in a commonplace environment at an inappropriate hour: Do we perceive beauty? Do we stop to appreciate it? Do we recognize the talent in an unexpected context?

    One of the possible conclusions from this experience could be:

    If we do not have a moment to stop and listen to one of the best musicians in the world playing the best music ever written, how many other things are we missing?
    http://www.facebook.com/photo......038;ref=nf

  13. semi OT:

    Here is a list of some fairly good videos on the cell and on the molecular machines in the cell

    Journey Inside The Cell – Stephen Meyer
    http://www.youtube.com/watch?v=1fiJupfbSpg

    The inner life of a cell – Harvard University – video
    http://www.youtube.com/watch?v=wJyUtbn0O5Y

    Programming of Life – Eukaryotic Cell – video
    http://www.youtube.com/user/Pr.....VCwDOMCpXY

    Ben Stein – EXPELLED – The Staggering Complexity Of The Cell – video
    http://www.metacafe.com/watch/4227700

    Through the Virtual Cell – video
    http://www.youtube.com/user/nd.....M2X1c4K1x0

    The Central Dogma (English version) – video
    http://www.youtube.com/watch?v=-ygpqVr7_xs

    Molecular Biology Animations – Demo Reel
    http://www.metacafe.com/w/5915291/

    DNA – Replication, Wrapping & Mitosis
    http://vimeo.com/33882804

    Here is a neat little video clip that I wish was a bit longer (they say a longer one is in the works):

    The Flow – Resonance Film – video
    Description: The Flow, from inside a cell, looks at the supervening layers of reality that we can observe, from quarks to nucleons to atoms and beyond. The deeper we go into the foundations of reality the more it loses its form, eventually becoming a pure mathematical conception.
    http://vimeo.com/groups/7286/videos/25430131

  14. Bacterial Flagellum – A Sheer Wonder Of Intelligent Design – video
    http://www.metacafe.com/watch/3994630

    The ATP Synthase Enzyme – exquisite motor necessary for first life – video
    http://www.youtube.com/watch?v=W3KxU63gcF4

    Powering the Cell: Mitochondria – video
    http://www.youtube.com/watch?v=RrS2uROUjK4

    Molecular Machine – Nuclear Pore Complex – Stephen C. Meyer – video
    http://www.metacafe.com/watch/4261990

    Kinesin Linear Motor – Video
    http://www.youtube.com/watch?v=kOeJwQ0OXc4

    Ribosome Translation High Quality – video
    http://pubs.acs.org/cen/multim.....erial.html

    Myosin – video
    http://www.youtube.com/watch?v=j8F5GGPACkQ

    The Virus – Assembly Of A Molecular “Lunar Landing” Machine – video
    http://www.metacafe.com/watch/4023122

    The following article has a list of 40 (yes, 40) irreducibly complex molecular machines in the cell:

    Molecular Machines in the Cell -
    http://www.discovery.org/a/14791

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