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07-16-2006
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A different person
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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?
Like any mystery, one has to look for clues to help explain the mystery. One way to begin to unravel the mystery is to look at motivation and means. The means of life is connected to genetics and self replication. The motivation is the accumulation of energy value and the lowering of entropy, against the opposing natural potential to lower energy and increase entropy.
Genetics are stable molecules and very conservative. Genetic changes are part of the natural pull to increase entropy within the cell. Life then tries to lower this entropy by integrating the disorder into its order. The diversity of life reflects increased entropy to reflect the natural pull. Life then tries to lower this entropy by placing life's diversity into coordinated eco-systems.
Humans are unique because we have free will. We are not restricted to the lower entropy coordination of natural instinct. Human can act on behalf of nature and increase the entropy of life. We can mess up eco-systems, so there is disorder. But humans are also life and can form cultures which can integrate or lower the entropy of billions of humans. The economies also allow better eating, so we can all store even more energy. Some store too much energy, but that is life.
Learning to use fire interfaced humans to the natural potentials to lower energy and increase entropy. We help nature when we add wood to the fire. Cooking food denatures proteins or increases its entropy so it is easier to digest. Eventually we also learned to take a side stream from fire and use that energy to lower entropy and increase energy in our building materials. For example, smelting iron puts the iron in a pure state implicit of lower entropy, relative to natural iron ores. It also stores potential energy (potential to oxidize). This was inevitable, seeing life's motivation. But nature is still at work, causing the iron to deteriorate over time, back to lower energy and higher entropy.
Lastly love is life because it lowers entropy. Hate follows the natural potential. It releases a lot of energy and increases disorder.
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Re: What constitutes Life?
Interesting HydrogenBond! But tell me how does your blog helps us to understand life? At best it describes Life in terms of a thermodynamic state function "Entropy" which in most cases is difficult to measure or calculate. For example can you tell me how to measure (or calculate) the entropy of an Egg or even the change that accompanies when it is cooked? I tried to address this question on Vimarsh, but succeeded rather usatifactorily, as you can see if you browse through my discussion in the following link:
Vimarsh :: View topic - Boiling of egg and Entropy |
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Re: What constitutes Life?
Using energy and entropy considerations gives a sense of logical direction to life. I have life moving toward higher energy value and lower entropy. I defined the direction of nature, using the standard definition of lower energy and higher entropy, with life a unique subset of nature.
Entropy is a nebulous concept. I see entropy in terms of degrees of freedom, disorder and randomness. If we lower entropy, we restrict the degrees of freedom, makes things more ordered, while also lowering the level of randomness. For example, there are left handed and right handed proteins, but only one of these is bio-active. Protein handedness, has lost one degree of freedom within life, losing a level of randomness that is common to the rest of nature.
Quantifying entropy is more difficult, but not impossible. I was just using an overview to show how this energy-entropy of life applies over the entire range of living expression. The next task is to go back to the basics to help make it quantitative.
Relative to an egg, when we cook a egg we denature the proteins. Before cooking, the proteins have a higher degree of order, using specific hydrogen bonding. After we heat, the entropy increases, permanently, since the proteins can't repack to the same level of order they had when formed by life. This will also eliminate the potential for life because it gains to much entropy. If we warm the egg and add only a small level of entropy, life reacts in a different way and begins to grow. But there is a limit to the entropy life can handle until life is gone and nature take over.
If we look at the cell, it is composed of many macromolecules. These large collection of atoms are one way to lower the entropy of atoms and small molecules. These can all be burnt in a calorimeter and will give off energy, reflecting their level of accumulated energy value.
Let us start at the membrane material called lipids. These are primarily small sections of polyethylene that use C and H. Pound for pound they contain the most energy value. Next, we have polysaccharides which are C, H, O. Then we have proteins, where are primarily C,HO and N. Then we have the genetic material which is primarily C, H, O, N, P. It is interesting as the energy value decreases (calorimetric), the molecules have added some additional atoms to the backbone. This places the genetic material closer to nature; lower energy, which may be why life began as replicators. It had to start closer to nature, and liberate from there.
Although the polyethylene backbone of lipids are very high energy molecules, nature will try to lower this energy value. One way is to add things to the ends, so pound for pound the energy value will decrease. Another way is to add proteins, into the lipid sea, since this will lower the energy value of the membrane.
From the point of view of the genetic material, it is starting at the bottom of the macromolecule energy value curve; pound for pound. Life will try to increase potential energy from that humble beginning.
Moving from RNA to DNA replicators followed this trend, since DNA is more reduced or has more H, defining more stored energy. When a cell is making RNA, is is making smaller templates with lower stored energy, pound for pound, since RNA is less reduced. This slightly favors nature. When the cells duplicates the DNA, it is creating higher level order (longer chains), with more potential energy pound for pound, favoring life.
It can gain potential further by lowering entropy, since lowering entropy means potential energy. Packing proteins help with this. But nature, always moving in the opposite way, will try to increase the entropy of the packed DNA or Chromosomes, creating another degree of freedom (mitosis).
It is hard to define life apart from the opposing pull of nature, since both directions are part of the dynamic state of life. Life reacts to both, trying to lower the overall entropy of the tug of war, by making the entire effect more and more efficient.
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Re: What constitutes Life?
Quote:
Originally Posted by HydrogenBond
I was just using an overview to show how this energy-entropy of life applies over the entire range of living expression. The next task is to go back to the basics to help make it quantitative.
Relative to an egg, when we cook a egg we denature the proteins. Before cooking, the proteins have a higher degree of order, using specific hydrogen bonding. After we heat, the entropy increases, permanently, since the proteins can't repack to the same level of order they had when formed by life. This will also eliminate the potential for life because it gains to much entropy. If we warm the egg and add only a small level of entropy, life reacts in a different way and begins to grow. But there is a limit to the entropy life can handle until life is gone and nature take over.
From the point of view of the genetic material, it is starting at the bottom of the macromolecule energy value curve; pound for pound. Life will try to increase potential energy from that humble beginning.
Moving from RNA to DNA replicators followed this trend, since DNA is more reduced or has more H, defining more stored energy. When a cell is making RNA, is is making smaller templates with lower stored energy, pound for pound, since RNA is less reduced. This slightly favors nature. When the cells duplicates the DNA, it is creating higher level order (longer chains), with more potential energy pound for pound, favoring life.
It can gain potential further by lowering entropy, since lowering entropy means potential energy. Packing proteins help with this. But nature, always moving in the opposite way, will try to increase the entropy of the packed DNA or Chromosomes, creating another degree of freedom (mitosis).
It is hard to define life apart from the opposing pull of nature, since both directions are part of the dynamic state of life. Life reacts to both, trying to lower the overall entropy of the tug of war, by making the entire effect more and more efficient.
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You seem to lack clarity  Let me explain!
Many processes in living systems are also irreversible (permanent) just is the case with the changes brought about by boiling an egg, so what is the logic of treating denaturation of proteins on boiling an egg?
Similarly, what is so special about the D- amino acids vis a vis L- amino acids? Most likely the fact that " there are left handed and right handed proteins, but only one of these is bio-active" is a result of chance, life could have originated differently, no one can rule out that alternate forms of life are also possible!
In chemistry, we know that there can be exothermic reactions as well as endothermic reactions, similarly there are examples in which entropy decreases for a spontaneous process, so life processes cannot be singled out in this over simplistic model.
Finally, we all know that no form of life perpetuates indefinitely, there is death, which invariably follows birth! How do you account for that in your entropic explanation of life?
We discussed about death on Vimarsh, perhaps you may be inclined to go through the discussion there which you may access through the link below:
Vimarsh :: View topic - How do we die? |
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Re: What constitutes Life?
One of the key components of life is water. Relative to other possible solvents for life, water exists at the lowest energy. In other words, if we burn most of the other possible solvents for life such as ammonia, alcohols, etc., water would be one of the final products because it is at the lowest energy.
Although water has the lowest energy, it also has the highest MP and BP of any similar weight molecule, implying it also has the lowest entropy. Ammonia or alcohols will evaporate with less energy (lower temperature) because they are already at higher entropy.
This extreme duality makes water unique, in that it best defines the "lowest energy" requirement of nature and the lower entropy requirement of life. Water has one leg in each world and acts as the mediator between nature and life.
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Re: What constitutes Life?
Quote:
Originally Posted by hallenrm
...there is death, which invariably follows birth! How do you account for that in your entropic explanation of life?
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I'm not sure about HB's take on things here, but....
As for entropy, it is not the life itself (being created or dying) that increases entropy; that would be a net gain of zero. It is the process of living that greatly increases entropy. Life processes ultimately convert sunlight into heat--as we eat plants and digest--ongoingly, relentlessly; regardless of the dip in entropy (recovered during decomposition) associated with the gestation....
And as agents of heat and mass transfer.... It's easy to see why a wizard once said:
"Life is just nature's way of turning light into heat."
Metaphorically....
Food is just packaged sunlight, right?
Some of the consumed energy goes to increasing the population of all us entropy generators, but in the end....
Isn't generating all that heat--just to maintain homeostasis--essentially maximizing entropy? |
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Re: What constitutes Life?
If you observe entropy decreasing, whether caused by "life" or an inanimate processes, then you are ignoring important aspects of the system being observed or you have just discovered a process which allows for perpetual motion, endless energy, or some other complete nonsense. NOTHING decreases entropy.
My brother-in-law, an otherwise intelligent man, once claimed that thermodynamics proves that evolutionary theory is incorrect, as life decreases entropy. I offered to lock him in a sealed closet for a month to test his hypothesis, and he immediately saw the flaw in his argument  |
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Re: What constitutes Life?
Relative to entropy, the impact of life may increase entropy. But life itself, as a pile of chemicals, defines lower entropy. For example, if we begin with all the input into the body and its partial conversion into an integrated mass of tens of billions of cells, each which is integrated onto itself, this is a decrease in entropy, relative to all the starting state of all these chemicals.
If we look at cancer, this is a semi-organized mass of cells, relative to any integrated system within the body of the same mass. Cancer will increase entropy within the body. Being in a state of replication, cancer will also use and release a lot of energy. Cancer works in the direction of nature. If left unchecked, the entropy will spread to body systems, which begin to lose their integration. Death leads to maximum entropy and lowest energy.
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Re: What constitutes Life?
Quote:
Originally Posted by HydrogenBond
Relative to entropy, the impact of life may increase entropy. But life itself, as a pile of chemicals, defines lower entropy. For example, if we begin with all the input into the body and its partial conversion into an integrated mass of tens of billions of cells, each which is integrated onto itself, this is a decrease in entropy, relative to all the starting state of all these chemicals.
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I wholeheartedly disagree. The decrease in entropy that you describe is observed because you are not taking into account the amount of loss in the system, or the living organism. There is heat loss, shedding of dead cells, and countless other ways that living organisms fail to even maintain entropy. You are failing to account for everything that makes up the system observed.
Put simply, you are cherry picking the factors involved in the system observed, and this is the reason why you appear to be observing decreased entropy. However, if you were to include every variable, you would see that with living things, as with everything else in the universe, entropy is never reduced.
ETA: I believe this line of discussion is now straying from the original topic. My intent is just to make the assertion that "life decreases entropy" is an incorrect statement and should not be included as one of the characteristics of what life is. |
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Re: What constitutes Life?
I understand the confusion. I am addressing the assemble of atoms and molecules, and not the impact of this assemble on the environment. Life is the assembly. If the assembly (cell) was trying to increase its own entropy, it would be breaking apart into smaller pieces, stopping and avoiding polymerization, cellular integration would need to break down, efficiency would need to drop, until nothing is coordinating and all atoms and molecules are heading in their own way. What you are referring to is death and not life.
If we look at life in terms of the impact of the cell (assembly) on the environment, so the living assembly can get the energy needed to increase energy and maintain or lower its entropy, it will lower energy and increase entropy within the external and internal environment, such as with digestion, metabolism, material recycle and waste removal.
These organelles within the cell are designed with nature in mind. But there will also be energy and material recycle for the purposes of life. Transport and synthesis is very ordered and very specific allowing the high efficiency needed to maintain the assembly against the opposing directions of nature. Cells (assemblies) could not continue to evolve, if the goal was higher entropy, since each generation could become more and more disorganized until only atoms appear. Evolution goes the other way, with higher efficiency and/or higher levels of integration adding new things to the integration from single to multicellular assemblies, with assembly entropy on the decrease.
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