polysaccharides

definition of polysaccharide

a complex carbohydrate formed from the condensation reactions of many repeated monosaccharides joined by glycosidic bonds

main types of polysaccharides found in living organisms

glycogen, starch and cellulose

property of polysaccharides that makes them suitable for storage?

they are insoluble, making them suitable for storage

properties of glycogen

• storage in animals

• made of many alpha glucose

• highly branched structure with 1,4 and 1,6 glycosidic bonds, allowing enzymes to rapidly hydrolyse glycogen into glucose (to be used in respiration)

• found in animal cells, particularly in liver and muscle cells

• insoluble, preventing osmotic effects in animal cells as it does not affect the water potential

• large molecule meaning it cannot diffuse out of cells

properties of starch

• storage in plants

• made of many alpha glucose molecules

• exists as amylose and amylopectin

• amylose - helical, unbranched structure with 1,4 glycosidic bonds, making it compact, which means that it can be stored in a small space

• amylopectin - branched, with 1,4 and 1,6 glycosidic bonds allowing rapid hydrolysis by enzymes to release glucose for respiration

• insoluble, preventing osmotic effects in plant cells as it does not affect the water potential

• large molecule meaning it cannot diffuse out of cells

properties of cellulose

• structural in plants

• made of many beta glucose molecules

• long, straight, unbranched chains with 1,4 glycosidic bonds

• straight chains held together by many hydrogen bonds to form microfibrils

• microfibrils joined together to make macrofibrils

• many hydrogen bonds help give structural strength to cellulose and plant cell walls, preventing plant cells from bursting under osmotic pressure