Part 1: Living cells are highly ordered units, yet the universe is heading towar
ID: 28960 • Letter: P
Question
Part 1: Living cells are highly ordered units, yet the universe is heading toward higher entropy. Discuss how life can maintain its order in spite of the second law of thermodynamics. Are we defying this law? Part 2: What is the advantage of using ATP as a common energy source? Another way of asking this question is, Why is ATP an advantage over using a bunch of different food molecules? For example, instead of just having a Na+/K+-ATPase in a cell, why not have a bunch of different ion pumps each driven by a different food molecule, like a Na+/K+-glucosase (a pump that uses glucose), a Na+/K+-sucrase (a pump that uses sucrose), a Na+/K+-fatty acidase (a pump that uses fatty acids), and so on?Explanation / Answer
ince the controversy between evolutionists and thermodynamics involves mainly the second law, we will only briefly look at the first law, sometimes referred to as the law of conservation, which tells us essentially that Nothing is now coming into existence or going out of existence; matter and energy may be converted into one another, but there is no net increase in the combined total of what exists. Regarding this first law, Isaac Asimov offers this noteworthy comment: “This law is considered the most powerful and most fundamental generalization about the universe that scientists have ever been able to make. No one knows why energy is conserved... All that anyone can say is that in over a century and a quarter of careful measurement scientists have never been able to point to a definite violation of energy conservation, either in the familiar everyday surroundings about us, or in the heavens above or in the atoms within.” More upstream why the carbon atom (as silicium could have similar properties) , is the main constituant of organic molecules ? why oxygen rather than fluor for oxydative properties ... and so on ... And these first "choice" of atoms by nature this could have influence the following, in particular molecules used in living organisms. Independently of energy, a lot of enzyme in reaction graft phosphates groups to over molecules; and in DNA synthesis, ATP is at the same time source of adenine and also source of energy and phosphosphate groups. Tyrosine kinase implicated in cellular division phosphorylates some membrane proteins, using ATP. So independently of energy, this molecule is used as substrate to provide phosphate, the phosporylated form of enzymes being active, and also allowing changing protein conformation. So, all the precedent render wider utilisation of ATP in cellular processess, in parallel with energy source. But why not GTP in this case (there is some G-proteins implicated in cellular process). Thermodynamicians could indicate us if using ATP for phosphorilation ie is less consumning energy than GTP ? (or differently said : balance between necessary energy before and possible recuparation of energy later is positive Perhaps have we also to eveluate the availability of adenine in nature (from alimentation), compared to guanine, cytosine for GTP and CTP. If theres is a reason for ATP, to my mind, its more upstream that we have to search an explanation, if we could be able to find it. Finally, in other "earths" in universe, perhaps exit living organsims like us, but built with silicium (Hoaw ! transparent ?) and breathing an atmosphere composed of fluor