Carbohydrates PDF

Carbohydrates  Role in energy/metabolic pathways Photosynthesis 6CO2 + 6H2O + energy C6H12O6 + 6O2 Cellular glucose Respiration Glucose, a simple carbohydrate is involve...

Carbohydrates  Role in energy/metabolic pathways Photosynthesis 6CO2 + 6H2O + energy C6H12O6 + 6O2 Cellular glucose Respiration Glucose, a simple carbohydrate is involved not only as the end product of photosynthesis but also as the starting point in cellular respiration and is critically important in living organisms.  Types of Carbohydrates Monosaccharides- the smallest carbohydrate units Disaccharides-two monosaccharides linked together Polysaccharides-many monosaccharides linked together Classification of Monosaccharides Classified by functional groups Classified by # of carbon atoms A monosaccharide with a ketone 3 carbons = triose functional group is called a 4 carbons=tetrose ketose 5 carbons= pentose A monosaccharide with an aldehyde functional group is 6 carbons =hexose called an aldose 7 carbons= heptose 8 carbons =octose  Examples of monosaccharides Aldose Ketose Aldose Aldose Hexose Pentose Tetrose Pentose  Structures of Glucose Even though the open chain structure is easiest to look at most of the glucose in our bodies is in one of these cyclic structures.  Oxidation of monosaccharides: Benedicts test Red Solid Selective oxidation. The Cu2+ ions are only powerful enough to oxidize the aldehyde leaving the alcohols alone Selective test for aldoses; ketoses do not oxidize in this test A simple color changing test; in a positive test the Cu2+ ions which are blue will turn into a red solid.  Formation of Disaccharides Disaccharides are formed by the combining of OH groups from 2 monosaccharides forming an “Ether like” linkage between the 2 monosaccharides and producing H2O as a byproduct This linkage typically happens from the OH groups on the 1 position of the first monosaccharide and the 4 position of the second monosaccharide The geometric orientation of the OH groups with respect to each other (up/down) will manifest itself in two different types of linkages in the product. Although the differences in the 2 forms is subtle these differences end up being critically important Alpha linkages Beta Linkages  Examples of Polysaccharides Amylose-20% of plant starch, alpha linkages, all 1-4 linkages so forms a straight chain structure Amylopectin-80% of plant starch, alpha linkages, mostly 1-4 linkages but will occasionally have a 1-6 linkage creating highly branched structures  Examples of Polysaccharides Continued Glycogen- animal starch that is stored in the liver and muscles. Alpha linkages, mostly 1-4 linkages but contains some 1-6 resulting in highly branched structures Cellulose-Forms the structural components of wood and plants. Formed from Beta 1-4 linkages forming straight chain structures. Humans are not able to break down and digest Beta linkages because we lack the enzymes to break down these linkages. Grazing animals such as cows, horses, deer, rabbits, etc are able to break down these Beta linkages because their digestive tracts have bacteria that possess the enzyme needed to break down these linkages.