Polysaccharides

Describe polysaccharides

• Formed by condensation of many glucose units

• Polysaccharides are insoluble so have no osmotic effect

How is glycogen formed?

• Condensation of a-glucose

How is cellulose formed?

Condensation of B-glucose

What type of bond forms between the glucose monomers in amylose?

1,,4 glycosidic bond

Which cell types have the most glycogen & why?

• Liver & muscle cells have a high concentration of. glycogen, as the cellular respiration rate is high in these cells

How does the structure of starch relate to its function?

Function = main energy store in plants.

‣ Polymer of alpha-glucose → joined by glycosidic bonds

formed by condensation reactions.

‣ Made of two polymers:

‣ AMYLOSE → long, unbranched chain (1,4-glycosidic bonds

only) → coiled → compact → good for storage → fit lots in a

small space.

‣ AMYLOPECTIN → long, branched chain (1,4 and 1,6-

glycosidic bonds) → branches allow enzymes to access &

hydrolyse glycosidic bonds easily → releases glucose

How does the

structure of glycogen

relate to its function?

1. ‣ Function = main energy store in animals.

   ‣ Polymer of alpha-glucose → joined by glycosidic bonds

   formed by condensation reactions.

   ‣ Long, highly branched (1,4 and 1,6-glycosidic bonds)→

   glycosidic bonds easily hydrolysed → releases lots of

   glucose quickly.

   ‣ Compact → good for storage → fit lots in a small space.

   ‣ Insoluble in water → doesn’t affect water potential of cell.

How does the structure of cellulose relate to its function?

• Function = structural role in plant cell walls.

• Properties of cellulose that make it suitable for use in cell walls = insoluble / high tensile strength / unreactive / flexible.

• Polymer of beta-glucose → joined by glycosidic bonds formed by condensation reactions.

• Every other beta-glucose monomer is rotated by 180°.

• Results in long, straight, unbranched chains → linked by hydrogen bonds → form microfibrils → strong, so provide structural support.

• Microfibrils join to form macrofibrils which combine to form fibres.