Chapter 14 Carbohydrates

Chapter Carbohydrates

Chemistry of Life

Carbohydrates are produced by photosynthesis in plants such as glucose are synthesized in plants from CO 2, H 2 O, and energy from the sun are oxidized in living cells to produce CO 2, H 2 O, 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 – 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