Concept 5.2: Carbohydrates provide fuel and building

material

Counting “Carbs” (aka Sugars)

• Carbohydrates contain carbon, hydrogen, and oxygen in the ratio: 1C : 2H : 1O

• Basic molecular formula: CH2O.

• Usually found as carbon skeletons that have a ring shape.

Which of the following is NOT a valid formula for a

carbohydrate?A. C4H10O4

B. C5H10O5

C. C6H12O6

D. C7H14O7

Basic molecular formula:

CH2O

“carbo”(carbon)

“hydrate”(water)

Carbohydrates Come in Many Forms

• Monomer = Monosaccharides Example: Glucose (C6H12O6)

• Dimer = DisaccharidesExample: Sucrose (C12H22O11)

• Polymer = PolysaccharidesExample: Starch

What is the name of this carbohydrate?

A. starchB. glucoseC. sucroseD. fructose

Note the six carbon atoms ina ring-shaped arrangement.

Glucose: C6H12O6

Lactose is a monosaccharide.

A. TrueB. False

Lactose

Lactose is a disaccharide composed of twomonosaccharides: glucose &galactose.

People who are “lactose intolerant” are unable tometabolize lactose.

MIL

K

Glucose is hydrophilic.

A. TrueB. False

This is due to its many hydroxyl groups. Recall that the hydroxyl functional group attracts water. Therefore, monosaccharides and disaccharides dissolve readily in water, forming sugary solutions. Starch and cellulose donot dissolve readily, but they do attract water.

Functions of Carbohydrates

1) Short Term Energy– Monosaccharides (plants & animals)

• Example: fructose

2) Long Term Energy– Polysaccharides

• Starch (plants)• Glycogen (animals)

3) Structure– Polysaccharides

• Cellulose (plant cell walls)• Chitin (animal exoskeletons)

potatoes turkey

cellulose chitin

Examples of Polysaccharides

Which of the following carbohydrates would you NOT

expect to find in a plant?

A. chitinB. starchC. glucoseD. cellulose

Chitin is found in the exoskeletons of arthropods like this spider, not in

plants.