In general, starch is confined to the plastid compartments of fruit cells, where it exists as
granules made up of both amylose and amylopectin molecules. The enzymes that catabolize
starch are also found in this compartment and their activities increase during ripening. The
glucose-1-phosphate generated by starch degradation (Fig. 3.2) is mobilized into the cytoplasm
where it can enter into various metabolic pools such as that of glycolysis (respiration),
pentose phosphate pathway, or for turnover reactions that replenish lost or damaged cellular
structures (cell wall components). It is important to visualize that the cell always tries to
extend its life under regular developmental conditions (the exceptions being programmed
cell death that occurs during hypersensitive response to kill invading pathogens, thus killing
both the pathogen and the cell/tissue, formation of xylem vessels, secondary xylem tissues,
etc.), and the turnover reactions are a part of maintaining the homeostasis. The cell ultimately
succumbs to the catabolic reactions during senescence. The compartmentalization
and storage of chemical energy in the form of metabolizable macromolecules are all the
inherent properties of life, which is defined as a struggle against increasing entropy