Science
Related: About this forumThe vital question: Why is life the way it is?
From phys.org:
Chemiosmosis refers to the movement of ions down an electrochemical gradient and across a selectively permeable membrane. This process was there at the begining in what is now widely held to be life's most diffuse state, the alkaline hydrothermal vent. The incidentals of a chemiosmotic lifestyle have continued to exert their influence at every major subsequent induction of new form since, each time further encapsulating both the primal elements of, and various substitutions in the original geochemistry. The explanation for why all life conserves energy in the form of proton gradients across membranes contains within itself the reason why one bacterium was ultimately able to get comfortable living inside another.
As Nick details, the constraints imposed on the evolution of life by chemiosmotic coupling ultimately dictate what he calls the greatest paradox in biology: that all life on earth is divided into prokaryotes, which lack morphological complexity, and eukaryotes, which share a massive number of perplexing traits never found in bacteria or archaea, including genome-wide sex, two sexes, and ageing. The gulf between the two families, and also among individual prokaryotic domains accordingly had less to do with adaptations for unique or extreme environments and more to do with the divergence of a group whose 'membranes were obliged to remain leaky for bioenergetic reasons.'
The main idea here is that without leaky membranes, the accumulation of protons inside a cell (or on the relavent side of a vent system operating at a specific pH) would quickly lead to a buildup of positive charge that opposes the influx of more H+. In this seemingly trivial description at least, activity across primitive membranes would eventually grind to a halt. In recent times Lane and his group have taken to the computer to provide insight into some of these effects, running all kinds of simulations to vet their hypotheses. We might mention here that these same simplistic intuitions apply to ATP accumulation in mitochondria. If ATP is generated at a higher rate than it is used, respiration grinds to a halt through the action of various inhibitory feedbacks. Low ATP consumption drives higher membrane potentials to higher levels making it even harder to pump protons. The respiratory complexes therefore gradually back up with excess electrons and leak away free radicals.
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Warpy
(111,383 posts)and some, like the tardigrade, have evolved to go into a state that allows them to survive temporary environmental conditions that kill everything else around them.
Conditions that don't incinerate or keep them at near absolute zero are probably going to present us with life forms. It could be a challenge to recognize them as such if the environment is significantly different from our own.
still_one
(92,454 posts)Binkie The Clown
(7,911 posts)Life is the way it is because the way it is works.
In other words, if a way doesn't work, then life is not that way, because if it was that way then it wouldn't work, and if it didn't work, it wouldn't be life.
Why are there fish in the ocean? Because that's where the water is.
phantom power
(25,966 posts)Reminds me of Kauffman's title "At Home In the Universe", which is a great book about a lot of very specific things not at all indicated by the title.
Jim__
(14,089 posts)The write-up makes the book sound interesting.