Polysaccharide found in many parts of a plant, it is made up of chains of alpha glucose monosaccharides linked by glycosidic bonds formed by condensation reactions. The unbranched chain is wound into a tight coil making the molecule very compact.
The main role of starch is as energy storage something especially suited for because:
- It is insoluble an therefore does not tend to draw water into the cells by osmosis
- being insoluble, it does not easily diffuse out of cells
- it is compact, so a lot of it can be stored in a small space
- when hydrolysed it forms alpha glucose, which is both easily transported and readily used in respiration.
- Starch is never found in animal cells but a similar polysaccharide, glycogen is.
Similar in structure to starch but has shorter chains…