Biology Reference
In-Depth Information
gradients (Ji 1974b, 1979, 2000). Enzymes are like someone borrowing a large
amount of money, M, from a bank overnight and paying it back before the bank
opens the next morning. The important ingredient here is this: The money, M
0
, used
to pay the bank back before it opens is not the same as M borrowed from the bank
during the night, because M was used to complete a business transaction during the
night which led to M
0
(which is assumed to be greater than M), out of which M was
paid back. In other words, although the
amount
of the money paid back is the same as
that of the money borrowed from the bank overnight, the
identity
of the money, M
0
,
can be different from that of the money, M, borrowed overnight. This analogy
explains what is meant by thermal energy playing an essential role in living
processes. Thermal energy is analogous to M and free energy is analogous to M
0
.
So, just as the profit, M
0
M, from the above imaginary business transaction required
the initial investment of money M borrowed from the bank, so the free energy
released, M
0
, from, say, the oxidation of NADH to NAD
+
, requires the initial input of
thermal energy, M, without which no catalysis can occur nor free energy released
from chemical reactions. We may refer to this analogy between
energies
and
monies
as the “
overnight-bank-loan analogy
(OBLA)” enzymic catalysis.
The content of OBLA is consistent with the Second Law of thermodynamics
reformulated in (McClare (1971) (see Sect.
2.1.4
below). McClare introduced time
into his reformulation of the Second Law so that the law now becomes applicable to
systems at the molecular level. If McClare's version of the Second Law is valid, the
application of the traditional version of the Second Law to molecular processes
such as Brownian motions may lead to invalid conclusions or contradictions.
Free energy is necessary but not sufficient for catalysis or for life. You can have
a cell population in a test tube with high concentration of nutrients such as glucose
and oxygen, but cells cannot use these nutrients to do any useful work such as
pumping ions or crawling around at 0
C, simply because enzymes cannot work at
this temperature due to lack of sufficient thermal energies or thermal fluctuations.
We can therefore make the following generalization:
Enzymes must first be “heated up” before they can catalyze chemical reactions to drive
living processes
(2.2)
Equivalently, we can state that:
Living processes cannot occur unless a sufficient amount of thermal energy is provided first
followed by free energy. (2.3)
Statement 2.3 may be referred to as the “thermal-energy-first-free-energy-later
(TEFFEL)” hypothesis.
2.1.3 The First Law of Thermodynamics
This law states that the energy of the Universe (or of any isolated system) remains
constant. In other words, the amount of energy of an isolated system cannot be
