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07-16-2006
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What constitutes Life?
The discussion started on - 05-19-2006, 01:21 PM , place HypographyClick here to read the entire article
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While engaged in the pursuit of the truth always be ready for the unexpected; for change alone is constant.
Last edited by hallenrm; 07-17-2006 at 10:52 PM..
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Re: What constitutes Life?
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Originally Posted by hallenrm
No, Rade, life is never self initiated  |
OK, use self generated if you do not like self initiated. What makes the fertilized egg alive ? It is the motion of matter and energy that occurs in a moment of time (e.g., it divides into two), and continues over time into the future, the cause of which derives from the self (e.g., the time sequence of the motion of "becoming" is directed by nucleic acids). There are no living things on earth that do not meet my definition of life, and no dead things that do. It is the definition that should be the first thing taught in a general biology class, which is the scientific study of life. So, class, what are we going to study in biology this year ? We will study all those entities that exist on earth that have self generated and self sustaining action over time mediated by a type of computer code found within nucleic acids. And they all have a goal, to continue to exist as a living entity, to continue playing the game. |
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Re: What constitutes Life?
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Originally Posted by HydrogenBond
Another component of life is the requirement of water. Many tests have demonstrated that we can not substitute any other solvent, for the water within a cell, and get the life requirements that have been listed. Other solvents have been proposed, for a separate chain of life, but only on paper.
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It is not clear that water must be the universal liquid medium that supports life--see this link:
Hypothetical types of biochemistry - Wikipedia, the free encyclopedia
If we limit our definition of life to the requirement that water molecules be present for chemical reactions to occur, we constrain the possibility of looking for life in other liquid mediums. Neither is it required that life be carbon based. If we look for a definition of life to help us find it in other places in the universe, the presence of water should not be necessary. A good first place to look if it is present, sure, but we need to expand the options to allow for the possibility that life can exist in liquid mediums other than water. |
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Re: What constitutes Life?
Water, although simple looking as a molecule, is actually one of the most complex substances in nature. It displays 63 known anomalies, relatives to the more predictable nature of other chemical substances. What that translates to; water is the odd duck of the chemical world. It is the perfect medium for life. If you want life to happen, you need the odd duck, since it plays by different rules.
For example, although we know water as H2O, this structure only exists in the liquid state for about 1 millisecond. It is constantly swapping H. This is reflected in the pH effect, although not limited to this. There is no such thing as ancient liquid water, unless ancient is less than a millisecond. Life is just as restless.
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Re: What constitutes Life?
Here is an interesting paper concerning water;
http://www.mdpi.com/1422-0067/10/5/2383/pdf
Quote:
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In the paper it is shown that the character of the translational and rotational thermal motions in water radically change near T H 315 K, which can be interpreted as the temperature of the smeared dynamic phase transition.
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This smeared dynamic phase transitions amounts to a phase change in the properties of water. What the authors go on to say that this temperature of transition coordinates with the upper limit of body temperature for warm blooded creatures. It effects the way water interacts with the materials within warm blooded creatures, causing the entire system to shut down. |
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Re: What constitutes Life?
The experiments involved in creating the "4 Stage Hypothesis for Origins of Life" (Urey and Miller) show that life was possibly created at a molecular level through the reactivity of certain chemicals. This supports some of the stances found in this thread.
1. Abiotic synthesis of organic monomers: Seawater plus gas atmosphere plus sparks discharged into system form organic monomers from chemical origins. (Experiments have since found all 20 amino acids, carbs, lipids and nucleotide monomers from this process.)
2. Abiotic synthesis of polymers: Solutions of monomers dripped onto hot rock, sand, or clay formed organic polymers via dehydration reactions.
3. Origin of self replicating molecules: Nucleotide monomers found in stage one and two form short RNA molecules, some begin to replicate.
4. Formation of pre-cells: Pre cells form from abiotically produced organic compounds. They have selective permeable surfaces and grow via absorption. They swell and divide, or shrink, in various salt concentrations.
At what point do we define life?
Self replication? Self-nonself recognition?
I think life - requires nutrition or energy (in any form that can be utilised, chemical or organic), replicates, interacts with it's environment, adapts and evolves.
A fluid thing, a dance that begins in extremely minute dimensions, of which the fluidity is not easily apparent except on a geological time scale or perhaps, in the forseeable future, at an atomic level.
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Re: What constitutes Life?
Life accumulates potential energy, even though most of nature goes in the direction of lower energy. Life eats and will lower the potential energy of food molecules, just like the rest of nature. But it also continuously uses some of that energy to accumulate potential energy within its many structures. Once it accumulates enough energy, it uses this potential to drive the replication. This will discharge some of its energy, but it also makes two cells that can now accumulate twice as much energy, total.
With multicellular, since the cells are integrated, this one life unit defines even more potential energy accumulated in one place in an integrated way. This orientation also defines less entropy, than the same number of independent cells not being connected. Lowering of the entropy is also going in the opposite direction of much of nature, which prefers to increase entropy. This is common to life, with small molecules becoming fixed into larger integrated structures.
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Re: What constitutes Life?
Despite the natural tendency, there seems to be a need to avoid entropy for survivals sake. As human organisms this is obviously apparent, but on other levels the same type things can be seen eg: bacteria of various genus working in concert via quorum sensing. I believe entropy is a kneejerk (natural) impulse of life to seek further resources. Colonisation has so many benefits and very few problems (vector for rapid pathogen/parasite transmission, competition, infanticide).
Nice points HB, got me to thinking about communal life at a new angle.
Life is the communal effect of atoms.
We of gargantuan mass who chase pheremones in the ether are merely exponentially massive representations of a multi billion year old design that started with a self replicating molecule.
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Last edited by Getting A Life; 10-09-2009 at 02:03 AM..
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Re: What constitutes Life?
If we start with a plant seed, which is fixing C, O and H via photosynthesis, the H2O and CO2 begin with high entropy as they float as gases in the clouds or move in a stream. Once fixed within the plant, they become stationary, lowering atomic and molecular entropy. As the plant grows, it is also storing potential energy. If this was a tree, we could burn it for heat, while increasing atomic entropy via the gases that are released.
Instead of a tree, say our plant becomes lettuce. A rabbit can lower the stored energy and can increase the entropy of the lettuce, by eating it. The evolution of plant eating animals is in line with the potential of nature to lower energy and increase entropy. While the animal is using the push of this natural path, it is also taking a side stream of energy value, and using that to store energy and lower entropy within its own structure. Whereas our lettuce is fixed to the earth, our rabbit has more degrees of freedom with respect to its movement. It is still lowering entropy in its structure, but its design has more degree of freedom, reflecting the pull toward higher entropy.
The wolf eats the rabbit, lowering the rabbits stored energy, while increasing the entropy of the rabbit, as it is digested into smaller pieces for metabolism. The wolf also takes a side stream, and being life it also stores energy and lowers entropy into its own structure. The ingenuity of the wolf as well as it more omnivore capability, allows it more options to lower energy and increase entropy in nature.
Working in packs, the wolf will also lower the entropy of individual wolves as they form their pack order. This leads to higher efficiency for the pack in terms of lowering energy increasing entropy in nature. This also allows each member to better fix energy potential, and lower entropy within themselves. As the pack gets tighter, they further increase energy and lowers entropy of the group, as they stop fighting and wasting energy, and learn to work as a integrated team.
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Re: What constitutes Life?
Life's property of lowering entropy and increasing stored energy, in the opposite directions of most natural processes, is also evident in neurons. These cells help nature by their high level of metabolism, which creates molecules like CO2 to increase their entropy.
Neurons, being life, will also take a side stream of this energy and use most of it to create a cationic gradient across the membrane. Potential energy is stored within the membrane potential. The sodium-potassium pumps also lowers the entropy of sodium and potassiums ions by segregating them. They would prefer maximize entropy by blending together.
To add to this life effect, potassium ions are kaotropic or will create disorder within water. They compete with the H-bonding. This will increase the entropy within water. Sodium ions are cosmotropic and will create order in water, thereby lowering water entropy. What this means, is the outside of the neuron membrane are more induced in the direction of life, with stored energy potential within the concentration gradient and lowered aqueous entropy due to the cosmotropic sodium ions. The outside of the membrane is where the potentials flow which help define the activity of consciousness. This begins another level of life which also stores energy and lowers entropy.
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Re: What constitutes Life?
Despite all the above discussion, life remains a mystery, if only because life is seldom found in isolation. A living being is alive only under a certain environment which includes other living beings. We had discussed it in a thread entitled "Mystery of Life" in an eforum that i presently administer, it is called Vimarsh. If you are interested to view it, please follow the link below:
Vimarsh :: View topic - The Mystery Of life |
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