+- نادي الفكر العربي (http://www.nadyelfikr.com)
+-- المنتدى: الســــــــاحات العامـــــــة (http://www.nadyelfikr.com/forumdisplay.php?fid=3)
+--- المنتدى: قضايا اجتماعيــــــة (http://www.nadyelfikr.com/forumdisplay.php?fid=60)
+---- المنتدى: اللغـات الأجنبيــة (http://www.nadyelfikr.com/forumdisplay.php?fid=16)
+---- الموضوع: The First Cell (/showthread.php?tid=14418)
The First Cell - skeptic - 10-13-2006
The First Cell arose in the previously pre-biotic world with the coming together of several entities that gave a single vesicle the unique chance to carry out three essential and quite different life processes. These were: (a) to copy informational macromolecules, (b) to carry out specific catalytic functions, and © to couple energy from the environment into usable chemical forms. These would foster subsequent cellular evolution and metabolism. Each of these three essential processes probably originated and was lost many times prior to The First Cell, but only when these three occurred together was life jump-started and Darwinian evolution of organisms began. The replication of informational molecules that made only occasional mistakes allowed evolution to form all the basic components of cellular life. Ribozymes, the first informational molecules, were also catalytic. Energy coupling required the formation of a closed lipid surface to generate and maintain an ion-motive gradient. The closed vesicle partitioned components and avoided dilution within the primordial sea. Closed membranes were essential for the first self-reproducing cell to arise and for its descendants to disperse. Subsequent cellular development after the origin of The First Cell led to the beginnings of intermediary metabolism and membrane transport processes. This long process, subject to strong evolutionary selection, developed the cellular biology that is now shared by all extant organisms.
Koch AL
Biology Department, Indiana University, Bloomington, IN 47405-6801, USA
2005
The First Cell - skeptic - 10-13-2006
Different viewpoints, many with deep Controversies on the origin
of life
philosophical and historical
roots, have shaped the scientific study of the origin of life. Some of these argue that
primeval life was based on simple anaerobic microorganisms able to use a wide
inventory of abiotic organic materials (i.e. a heterotrophic origin), whereas others
invoke a more sophisticated organization, one that thrived on simple inorganic molecules
(i.e. an autotrophic origin). While many scientists assume that life started as
a self-replicative molecule, the first gene, a primitive self-catalytic metabolic network
has also been proposed as a starting point. Even the emergence of the cell
itself is a contentious issue: did boundaries and compartments appear early or late
during life's origin? Starting with a recent definition of life, based on concepts of
autonomy and open-ended evolution, it is proposed here that, firstly, organic molecules
self-organized in a primordial metabolism located inside protocells. The
flow of matter and energy across those early molecular systems allowed the generation
of more ordered states, forming the cradle of the first genetic records. Thus,
the origin of life was a process initiated within ecologically interconnected
autonomous compartments that evolved into cells with hereditary and true
Darwinian evolutionary capabilities. In other words, the individual existence of life
preceded its historical-collective dimension.
The First Cell - skeptic - 10-13-2006
http://www.rogepost.com/dn/lqgp
The First Cell - The Godfather - 10-30-2006
Thank you
I think this article should matter to all atheists and theists alike.