3.  Composed of C, H, and O  General molecular formular – CH 2 O  Function: ◦ Energy ◦ Energy storage ◦ Raw materials ◦ Structural materials  Monomer: sugars  Examples: sugars, starches, cellulose

4.  Most names for sugars end in –ose  Classified by number of carbons ◦ 6 carbons – glucose ◦ 5 carbons – ribose ◦ 3 carbons - glyceraldehyde

5.  5 C and 6 C sugars form rings in solutions

7.  Monosaccharides ◦ Simple 1 monomer sugars ◦ Glucose  Disaccharides ◦ 2 monomers ◦ Sucrose  Polysaccharides ◦ Many monomers ◦ Starch, cellulose

8.  Dehydration synthesis

9.  Polymers of sugars ◦ Costs little energy to build ◦ Easily reversible = releases energy  Function ◦ Energy storage  Starch (plants)  Glycogen (liver and muscles of animals) ◦ Structure  Cellulose (cell wall of plants)  Chitin (arthropods and fungi)

10.  Molecular structure determines function

11.  Starch – easy to digest  Cellulose – hard to digest

12.  Most abundant organic compound on Earth ◦ Herbivores have evolved a mechanism to digest cellulose ◦ Most carnivores have not  That’s why they eat meat to get their energy and nutrients  Cellulose = undigestable roughage

13.  How can herbivores digest cellulose so well? ◦ Bacteria live in their digestive systems and help digest cellulose-rich food