Posted 16 December 2007 - 02:06 PM
One way to look at the energetics of life is to look at the hydrogen. If you look at H2, all by itself, without any other atoms present, the H is at its lowest possible energy state. This is reflected in solid hydrogen having the lowest melting point of any material in nature. In other words, the H in H2 is so stable there is almost no surface potential for attraction.
Although H2 is very stable by itself, the H2 is a high energy molecule with respect to oxygen. In this case, the potential for change is within the O and not in the H, since to become H2O, although the system energy is lower, the H now has a potential. In other words, the H2 doesn't interact but the H in H2O will interact strongly via hydrogen bonding. The H2 and O2 system energy is lowest as H20. The O's energy is also lowest as H2O. But hydrogen gains potential by becoming water, i.e., dipole charge.
That being said, when cells accumulates reduced food molecules,i.e., C-H, it is placing the H is a very low energy state relartive to H2, since both C and H have similar electro negativities. This low energy state for H is high energy with respect to O. The cell is designed to lower the potential of the H. But by lowering the H potential, the cell increases the O potential, until the system needs to discharge, driving the cell cycle.
At the lower end of hydrogen potential we have H2, which very few cells can make. The drag of the O, by going in the opposite direction makes this difficult. The cell sort of settles on low potential H using C-H, then N-H and then O-H. The latter, in turn, uses hydrogen bonding states. The H+ is the other end of the H spectrum having maximum potential.
An analogy of the cell are children in a playground. The lowest system energy will typically involve the biggest kids dominating play. The big kids are sort of O which be define the lowest system energy. The little kids (H) can't play easily with the aggressive big kids, dominating. The rest of inert nature is dominate by the big kids called oxygen, end of story. The cell is sort of like a teacher that comes to the playground to even the play allowing the small kids to participate in the games. But by doing this, the big kids are not allowed to play at full pace, so the little kids can better participate. But eventually, the teacher is called away (cell cycle) and the big kids take over again as the cell metabolizes very aggressively. But eventually the teacher returns (new cell) and helps the little kids so they can play.