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Author Topic:   Cell Division
Drevmar
Junior Member (Idle past 2295 days)
Posts: 24
From: Spokane, WA, USA
Joined: 02-17-2011


Message 1 of 32 (605265)
02-17-2011 11:55 PM


Why did the first cell divide? How could it have programmed itself to do that? Why would the first cell divide, why didn't it just live its life and then die? If there are actual, plausible scientific answers I am interested in hearing them.
Replies to this message:
 Message 3 by Dr Jack, posted 02-18-2011 6:06 AM Drevmar has not yet responded
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 Message 5 by Taq, posted 02-18-2011 12:57 PM Drevmar has not yet responded

    
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Message 2 of 32 (605267)
02-18-2011 5:51 AM


Thread Copied from Proposed New Topics Forum
Thread copied here from the Cell Division thread in the Proposed New Topics forum.
    
Dr Jack
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From: Leicester, England
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Message 3 of 32 (605269)
02-18-2011 6:06 AM
Reply to: Message 1 by Drevmar
02-17-2011 11:55 PM


Most likely it was simply physics; it grew to a sufficient size that the physical forces on it were sufficient to tear the cell into two parts. That's what lipid vesicles do.

Of course it was then just luck whether the two halves contained what they needed to survive. Sometimes one part would contain everything; sometimes both of them wouldn't. This, then, applies a strong selective pressure towards mechanisms that control the process of division and ensure that both daughter cells contain the correct elements - and we have the beginnings of mitosis.


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Dr Adequate
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Message 4 of 32 (605276)
02-18-2011 7:36 AM
Reply to: Message 1 by Drevmar
02-17-2011 11:55 PM


Lipids will spontaneously form liposomes --- (roughly) spherical cells with bilipid layers, and these will spontaneously divide and fuse. (When I say spontaneously, I mean that no biological mechanism is required, it's just down to the physics of the lipids.) Note that fission does not spill the contents of the liposomes.

So you could perfectly well have cell fission, in this sense, before you actually had life! --- and then life co-opted this ready-made process. The challenge then would be how best to regulate it.

In this paper, the author comments:

Because liposomes undergo spontaneous fission and fusion, and are subject to osmotic forces, size regulation in the earliest protocells would essentially have been liposome physics. For successful protocells, averting osmotic lysis would have been the first order of business. However, from the outset size mattered too, because of sex and reproduction (i.e., genome mixing and genome copying in entities with phenotypes). Protocell fission and fusion would have blended seamlessly into protocell sex and reproduction, making any gene product that furnished control over protocell size changes doubly adaptive.

So protocells didn't have to be programmed to divide, as such --- but once life started using these membranes, it was adaptive to acquire control over the process of division. It seems reasonable that any control would have been better than none, and more better than less, making this adaptation a prime candidate for evolution.

Edited by Dr Adequate, : No reason given.


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Taq
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(1)
Message 5 of 32 (605309)
02-18-2011 12:57 PM
Reply to: Message 1 by Drevmar
02-17-2011 11:55 PM


Why did the first cell divide? How could it have programmed itself to do that?

Why does ice form hexagonal crystals, and how did it program itself to do that?

Why would the first cell divide, why didn't it just live its life and then die?

It is entirely possible that the first cell did just that. It lived it's life and died leaving no descendants. If you think about it for just a few seconds I think the answer to this questions should be very obvious. Why is it that we only see the descendants of dividing cells in today's world?

Edited by Adminnemooseus, : Eliminate redundant and blotched quote.


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 Message 1 by Drevmar, posted 02-17-2011 11:55 PM Drevmar has not yet responded

  
Drevmar
Junior Member (Idle past 2295 days)
Posts: 24
From: Spokane, WA, USA
Joined: 02-17-2011


Message 6 of 32 (605382)
02-18-2011 10:25 PM


Very astute and much to think about, thank you very much!
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RAZD
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Message 7 of 32 (605447)
02-19-2011 7:18 PM
Reply to: Message 6 by Drevmar
02-18-2011 10:25 PM


Hi Drevmar. and welcome to the fray.

Very astute and much to think about, thank you very much!

This is a great site for learning things, and finding out where your preconceptions may be in error when discussing things with people educated in the various fields that visit and share. I know I've learned a lot here/

Enjoy.

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we are limited in our ability to understand
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This message is a reply to:
 Message 6 by Drevmar, posted 02-18-2011 10:25 PM Drevmar has responded

Replies to this message:
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Drevmar
Junior Member (Idle past 2295 days)
Posts: 24
From: Spokane, WA, USA
Joined: 02-17-2011


Message 8 of 32 (605455)
02-19-2011 9:22 PM
Reply to: Message 7 by RAZD
02-19-2011 7:18 PM


To RAZD
Thanks for the info on that I will attempt it in the future!
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RAZD
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Posts: 18970
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.8


Message 9 of 32 (605457)
02-19-2011 9:43 PM
Reply to: Message 8 by Drevmar
02-19-2011 9:22 PM


Re: To RAZD
Drevmar, your welcome.

Thanks for your question. btw - you may want to read Self-Replicating Molecules - Life's Building Blocks, Part II and watch the video on the possible protocells that have been discussed here.

Enjoy

Edited by RAZD, : ...


we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)

This message is a reply to:
 Message 8 by Drevmar, posted 02-19-2011 9:22 PM Drevmar has not yet responded

Replies to this message:
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shadow71
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Posts: 706
From: Joliet, il, USA
Joined: 08-31-2010


Message 10 of 32 (605545)
02-20-2011 7:21 PM
Reply to: Message 9 by RAZD
02-19-2011 9:43 PM


Re: To RAZD
razd posted;

Thanks for your question. btw - you may want to read Self-Replicating Molecules - Life's Building Blocks, Part II and watch the video on the possible protocells that have been discussed here.

Hi Razd, I watched the video. The music was great. But if this is science's answer to the orgin of life, you guys are in big trouble.

On this board I have been critized for speculating, dreaming, not showing the evidence etc. and then you have the nerve to show this video?

I think Dr. Szostak should take a couple of years sabbatical and think about his life and studies.

I acutally laughed through most of the "important parts" of the video.

Yes maybe life began that way, and maybe my grandsons theory of the easter bunny is valid.

I would but my money on my grandsons, and they are only 2yr, 18mo. and 7mo.

I'm sure Anthony Flew would get a kick out of that video. Remember he said;

"My departure from atheism was not occasioned by any new phenomenon or argument. Over the last two decades my whole framework of thought has been in a state of migration.This was a consequence of my continuing assessment of the evidence of nature. When I finally came to recognize the existence of a God, it was not a paradigm shift, because my paradigm remains, as Plato in his Republic scriped his Socrates to insist: 'We must follow the argument wherever it leads'."

The argument for the orgin of life does not lead to Dr. Szostak's thoughts or theory.


This message is a reply to:
 Message 9 by RAZD, posted 02-19-2011 9:43 PM RAZD has responded

Replies to this message:
 Message 11 by RAZD, posted 02-20-2011 8:01 PM shadow71 has responded
 Message 12 by Dr Adequate, posted 02-20-2011 8:01 PM shadow71 has responded

    
RAZD
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Posts: 18970
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.8


Message 11 of 32 (605550)
02-20-2011 8:01 PM
Reply to: Message 10 by shadow71
02-20-2011 7:21 PM


Re: To RAZD
Hi shadow71,

Hi Razd, I watched the video. The music was great. But if this is science's answer to the orgin of life, you guys are in big trouble.

Amusingly the application of the video to this thread was about the formation of proto-cells and how cells divide, as discussed in the other posts and which this video showed in detail, based on actual experiments conducted in actual labs. Perhaps you should read Message 1 and the replies first.

I acutally laughed through most of the "important parts" of the video.

Cognitive dissonance is like that.

On this board I have been critized for speculating, dreaming, not showing the evidence etc. and then you have the nerve to show this video?

Did you read the rest of the article? You will see that each element is referenced. If you want to discuss the actual science with Dr Szostak, he has a website where you can contact him: http://genetics.mgh.harvard.edu/szostakweb/ - see people and I believe that it is referenced in the video.

Yes maybe life began that way, ...

Which, curiously, is all we can say at this time. Nobody is claiming that this is what happened, only that it is one possibility, one that works with known science and natural processes.

Enjoy.

Edited by RAZD, : clrty


we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)

This message is a reply to:
 Message 10 by shadow71, posted 02-20-2011 7:21 PM shadow71 has responded

Replies to this message:
 Message 19 by shadow71, posted 02-21-2011 7:18 PM RAZD has responded

  
Dr Adequate
Member
Posts: 15950
Joined: 07-20-2006
Member Rating: 4.2


Message 12 of 32 (605552)
02-20-2011 8:01 PM
Reply to: Message 10 by shadow71
02-20-2011 7:21 PM


Re: To RAZD
Incredulity is not an argument. Do you have any specific and science-based criticism, or do the fact that you laughed and an irrelevant quotation from Dr Flew constitute all you have to say for yourself?

We can watch liposomes dividing in a laboratory; we know it happens. If, as I suspect, you have a magic-based hypothesis, I should like you to produce equally strong evidence for the occurrence of magic. Otherwise I shall prefer the reality-based hypothesis to yours unless and until I have further data.

Edited by Dr Adequate, : No reason given.


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 Message 10 by shadow71, posted 02-20-2011 7:21 PM shadow71 has responded

Replies to this message:
 Message 13 by Drevmar, posted 02-21-2011 12:36 AM Dr Adequate has not yet responded
 Message 18 by shadow71, posted 02-21-2011 7:13 PM Dr Adequate has responded

  
Drevmar
Junior Member (Idle past 2295 days)
Posts: 24
From: Spokane, WA, USA
Joined: 02-17-2011


Message 13 of 32 (605583)
02-21-2011 12:36 AM
Reply to: Message 12 by Dr Adequate
02-20-2011 8:01 PM


Re: To RAZD
I appreciate the link to the Self-Replicating Molecules, I haven't looked at it yet, but I will, thank you.
This message is a reply to:
 Message 12 by Dr Adequate, posted 02-20-2011 8:01 PM Dr Adequate has not yet responded

Replies to this message:
 Message 14 by Drevmar, posted 02-21-2011 1:21 AM Drevmar has not yet responded

    
Drevmar
Junior Member (Idle past 2295 days)
Posts: 24
From: Spokane, WA, USA
Joined: 02-17-2011


Message 14 of 32 (605590)
02-21-2011 1:21 AM
Reply to: Message 13 by Drevmar
02-21-2011 12:36 AM


Re: To RAZD
Okay, I went to the link you provided and I have to admit, I had to look up "self-polymerize" - this stuff is really slow reading for me. I'll have to look at it a few times before I am gonna get it. But I think the main gist is that we are talking about chemicals getting together, forming into a very basic cell-like structure, replicating and then picking and choosing this and that until they achieve life-form? The attached reading material is somewhat difficult as well and has a lot of "out of my league" stuff. I feel the need to ask if a life-form has been developed in a lab? or, is the current state of development still chemical compounds? No insult intended I just want to know!
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Replies to this message:
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Dr Jack
Member
Posts: 3506
From: Leicester, England
Joined: 07-14-2003


Message 15 of 32 (605605)
02-21-2011 4:33 AM
Reply to: Message 14 by Drevmar
02-21-2011 1:21 AM


Many ideas
I believe that's a pretty accurate description of the hypothesis presented, yes. Although I'd note that it's just one suggestion; one that is popular among those on this board, but by no means the "accepted" account. An alternative view has life evolving initially in the microstructure of rocks, and only later developing cell membranes.

I feel the need to ask if a life-form has been developed in a lab? or, is the current state of development still chemical compounds?

No origin of life experiment so far has come close to anything that might be called living from non-replicating components.


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