Polysaccharides Notes

Polysaccharides

• Polysaccharides are polymers of glucose.
• Different monosaccharides are linked together using dehydration synthesis reactions to form several different polysaccharides.
• The three most important polysaccharides are:
  • Starch
  • Glycogen
  • Cellulose

Starch

• Different organisms link monosaccharides together to form several different polysaccharides.
• The most important 3 are starch, glycogen, and cellulose.
• Starch is used for long term energy storage in plants.
• Can be branched (amylopectin) or unbranched (amylose).

Glycogen

• Glycogen has the same kind of bond between monomers as starch but it is always highly branched.
• It is used for long-term energy storage in animals, and in muscles to provide a local supply of energy when needed.
• Glycogen can be broken down by a hydrolysis reaction to obtain glucose when organisms need energy.

Cellulose

• Cellulose is a carbohydrate used to make cell walls in plants.
• Cellulose has a different kind of bond between glucose molecules, forming chains that are cross-linked by hydrogen bonds.

Breakdown of Cellulose

• Because cellulose is the principal structural molecule in cell walls of plants, it needs to be strong.
• Animals cannot break down cellulose without the help of intestinal bacteria.
• It is commonly referred to as fiber.

Getting Usable Energy

• In order for cells to obtain energy from polysaccharides, they must be first broken down into monosaccharides.
• Hydrolysis occurs, breaking the polysaccharide into glucose molecules.