Carbohydrates

Carbohydrates – energy molecules

Composed of C, H, and O General molecular formular – CH2O Function:

◦ Energy◦ Energy storage◦ Raw materials◦ Structural materials

Monomer: sugars Examples: sugars, starches, cellulose

Carbohydrates

Most names for sugars end in –ose Classified by number of carbons

◦ 6 carbons – glucose◦ 5 carbons – ribose◦ 3 carbons - glyceraldehyde

Carbohydrates

5 C and 6 C sugars form rings in solutions

Sugar Structure

Carbons are always numbered

Monosaccharides◦ Simple 1 monomer sugars◦ Glucose

Disaccharides◦ 2 monomers◦ Sucrose

Polysaccharides◦ Many monomers◦ Starch, cellulose

Simple and Complex Sugars

Dehydration synthesis

Building Sugars

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)

Polysaccharides

Molecular structure determines function

Polysaccharide Diversity

Starch – easy to digest

Cellulose – hard to digest

Digesting Starch vs. Cellulose

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

Cellulose

How can herbivores digest cellulose so well? ◦ Bacteria live in their digestive systems and help

digest cellulose-rich food

Helpful Bacteria