1. Starch: a compact plant energy store
Specification: 3.1.2 · Starch structure and function
Starch is built from alpha-glucose and consists of amylose and amylopectin. Amylose is an unbranched polymer with α(1→4) glycosidic bonds and coils into a helical shape. Amylopectin contains α(1→4) chains with α(1→6) branches.
Starch is largely insoluble, so it does not markedly lower the water potential of the cell and is suitable for storage. Its compact organisation allows many glucose units to be stored in a relatively small volume.
Branches in amylopectin offer multiple ends for enzyme action, making glucose units more accessible than if there were only one chain end.