PPT for EDEXCEL AS Biology

1. CARBOHYDRATES 2:
POLYSACCHARIDES

2. Learning objectives
• Know the difference between monosaccharides,
disaccharides and polysaccharides, including glycogen
and starch.
• Explain how monosaccharides join to form
polysaccharides through condensation reactions forming
glycosidic bonds, and how these can be split through
hydrolysis reactions.
• Relate the structures of monosaccharides, disaccharides
and polysaccharides to their roles in providing and
storing energy.

3. Introduction
• Polysaccharides, the polymers of sugars,
have storage and structural roles
• The structure and function of a
polysaccharide are determined by its sugar
monomers and the positions of glycosidic
linkages

4. Cellular respiration

6. Starch
• Starch, a storage polysaccharide of plants,
consists entirely of glucose monomers
• Plants store surplus starch as granules within
chloroplasts and other plastids
• Two major types are:
• 1. Amylose- contains only 1,4 glycosidic bonds
• 2. Amylopectin- contains 1,4 and 1,6 glycosidic
bonds.
• Amylopectin releases glucose units more rapidly.

8. Glycogen
• Glycogen is a storage polysaccharide in
animals and fungi, also known as “animal
starch”
• Humans and other vertebrates store
glycogen mainly in liver and muscle cells
• Very similar with amylopectin, but
contains more 1,6 glycosidic bonds.