Starch

• Starch is a polysaccharide that is found in many parts of a plant in the form of small grains.
• The two main types of starch are amylose and amylopectin.
• Starch forms an important component of food and is the major energy source in most diets.
• Starch is made up of chains of alpha-glucose monosaccharides linked by glycosidic bonds that are formed by condensation reactions.
• Starch chains may be branched or unbranched.
• The unbranched chain in starch is wound into a tight coil that makes the molecule very compact.
• Structure of starch:

  
• The main role of starch is energy storage.
• Starch is adapted by: it is insoluble and therefore dosen't affect water potenial, so water isn't drawn into the cells by osmosis.
• Starch is adapted by: it is compact, so a lot can be stored in a small space
• Starch is adapted by: being large and insoluble, it dosen't diffuse out of cells
• Starch is adapted by: When hydrolysed it forms alpha-glucose, which is both easily transported and readily used in respiration.
• Starch is adapted by: the branched form has many ends, each of which can be acted on by enzymes simultaneously meaning that glucose monomers are released very rapidly.
• Starch is never found in animal cells.