Chapter 14

Carbohydrates

Chapter 14

14.1 - Carbohydrates

Chemistry of Life

Carbohydrates

are produced by photosynthesis in plants

such as glucose are synthesized in plants from CO2, H2O, and energy from the sun

are oxidized in living cells to produce CO2, H2O, and energy

Types of Carbohydrates

monosaccharides, the simplest carbohydrates disaccharides, consist of two monosaccharides polysaccharides, contain many monosaccharides

Monosaccharides consist of

3-6 carbon atoms typically a carbonyl group

aldehyde (aldose) ketone (ketose)

several hydroxyl groups carbohydrates that cannot be

split (or broken down) in to

smaller carbohydrates

Monosaccharides (based on # of C)

Chapter 14

14.2 – Structure of Monosaccharides

Fischer Projections

Identifying D and L Isomers

Look for the chiral carbon furthest from the carbonyl group

Which direction is the hydroxyl group pointing in when the carbonyl group is drawn at the top?

If its on left –

give a L designation If its on right –

give a D designation

Important Monosaccharides

Most common hexose is D-glucose

(also known as dextrose or blood sugar) Found in fruits, vegis, corn syrup & honey Building block of disaccharides:

sucrose, lactose and maltose Building block of disaccharides:

starch, cellulose and glycogen

Important Monosaccharides

Galactose is an aldohexose that does not occur in the free form in nature

Obtained as a hydrolysis product of

the disaccharide lactose Important in the cellular membranes

of the brain and nervous system Only difference from D-glucose is

the –OH arrangement on C #4

Important Monosaccharides

Fructose is the sweetest carbohydrate (2x as sweet as sucrose – table sugar)

After it enters the bloodstream it is

converted to glucose Found in fruit juices and honey Also called levulose and fruit sugar Also obtained as one of the

hydrolysis products of sucrose

Important Monosaccharides