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Author Topic:   Self-Replicating Molecules - Life's Building Blocks (Part II)
granpa
Member (Idle past 572 days)
Posts: 128
Joined: 10-26-2010


Message 20 of 97 (612871)
04-19-2011 4:55 PM
Reply to: Message 8 by Dr Jack
07-04-2009 1:24 PM


Mr Jack writes:

Two tailed lipids will spontaneously form bilayered spheres (called liposomes), yes, but one-tailed lipids (aka detergents) form micelles (little balls without an inside) instead - and here's the problem - detergents disrupt the formation of liposomes.

I'm not sure how this problem is supposed to be addressed.

lipids can also stack into 1 dimensional structures.

In the primordial ocean, these would grow from the ends until they became capped but some (possible rare) side linking subunits could link to the sides and thereby allow the structure to branch. These molecules would reproduce but could not evolve.

to get a fully RNA-like self reproducing molecule (capable of evolving) you would need some kind of environmental selection that would concentrate these side linking subunits until they were nearly all that was left.

http://en.wikipedia.org/wiki/PAH_world_hypothesis

quote:
Polycyclic aromatic hydrocarbons are the most common and abundant of the known polyatomic molecules in the visible Universe, and are considered a likely constituent of the primordial sea.[4] PAHs, along with fullerenes (or "buckyballs"), have been recently detected in nebulae.

PAH's are not normally very soluble in sea water, but when subject to ionizing radiation such as solar UV light, the outer hydrogen atoms can be stripped off and replaced with a hydroxyl group, rendering the PAHs far more soluble in water.

These modified PAHs are amphiphilic, which means that they have parts that are both hydrophilic and hydrophobic. When in solution, they assemble in discotic mesogenic stacks which, like lipids, tend to organize with their hydrophobic parts protected.


Edited by granpa, : spelling

Edited by granpa, : clarification

Edited by granpa, : add color and remove side material

Edited by granpa, : clarification

Edited by granpa, : added quote of message I am replying to.

Edited by granpa, : become capped

Edited by granpa, : In the primordial ocean


This message is a reply to:
 Message 8 by Dr Jack, posted 07-04-2009 1:24 PM Dr Jack has not yet responded

  
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