Metabolism
organism; all energy and material transformations that occur within living cells. It includes essentially
the
material changes (i.e., changes undergone by substances during all periods of life, for instance:
growth, maturity, and senescence), and
energy changes (i.e., all transformations of chemical energy of
food stuffs to mechanical energy or heat). Metabolism involves
two fundamental processes, namely:
anabolism
(viz., assimilation or building-up processes), and catabolism (viz., disintegration or tearing,
down processes). Anabolism is the conversion of ingested substances into the constituents of
protoplasm;
Catabolism
is the breakdown of substances into simpler substances, the end products usually being
excreted.
The broad spectrum of these reactions gives rise to a plethora of excellent opportunities to characterize
and differentiate categories of microorganisms.
Examples:
(
a) Absorption of Light: Certain microbes may derive energy via absorption of light.
(
b) Oxidation: A few microorganisms may obtain energy through oxidation of a host of inorganic
and organic compounds.
(
c) Redistribution of Atoms: Some organisms engage actively in the redistribution of atoms
within certain molecules thereby rendering the resulting molecules less stable.
(
d) Synthesis of Cell Components: The microorganisms also vary a lot in the manner whereby
they invariably synthesize their prevailing cell components in the course of their usual growth.
(
e) Role of Enzymes: The wide variety of chemical reactions of an organism are duly catalyzed
by certain proteineous substances termed as
enzymes. Interestingly, the complement of enzymes
invariably owned by one specific type of organism, and the manners whereby such
enzymes are meticulously modulated, may differ rather appreciably from that of other microbes.