University:
Emory University
Course:
CHEM 141 | General Chemistry I
Academic year:

2021
Views:

370

Pages:

3
Author:

Aiden F.

Carbohydrates Cont. Lecture 04 20 21 Disaccharides Maltose, often called malt sugar, is present in fermenting grains and can be prepared by enzyme-catalyzed degradation of starch. Is it is used in prepared foods as a sweetener. Lactose (milk sugar) is a disaccharide composed of B-D-galactose and B-D-glucose. ↳ The two monosaccharides are connected by a B-1, 4 link Glyceofie hood at 14 link CHOH CH.OH lumiscetal at Ci CHOH OH OH CHOH OH CH --Glucane 011 3-Glucose CH pe-Galactose OH CH₂OH OH OH a-D-Glucose HOCH 1,2 anomeric link Bo-Fructose HOA2 CH₂OH OH Polysaccharides Polysaccharides are polymers of tens, hundreds, or even Sucrose many thousands of monosaccharides linked together through glycosidic bonds. - Three of the most important polysaccharides are cellulose. Starch, and glycogen. Starch is fully digestible and is an essential part of the human diet. Only OM SEND termites, moths, cows and other grazing animals are able to digest cellulose. - Amylose accounts for about 20% of starch and consists of up to 1000d-D-glucose units connected by a-1,4 links. Instead of lying side by side and fiat as in cellulose, amylose tends to coil into helices. Amylopcetin, which accounts for about 80%. of starch, is similar to amylose but has much larger molecules Cup to 100,000 glucose units per molecule) and has a-1, 6 branches approx. cvery 25 units along its chain. Branch point in amylopectas (also glycugend Amylopectin 20 110 CHOHO HO hlink Amylose HO- HO H CH 07 link HO- CH.OHO HO 11 110 - Glycogen Canimal starch), is similar to amylopectin in being a long polymer of a-D-glucose with the same type of branch points in its chain Glycogen has many more branches than amylopectin and is larger, with up to I million glucose units per molecule. - Another abundant linear polysaccharide in nature is Chitin. Chitin consists of repeating N-acetylglucosamine units Carbohydrate Links - Carbohydrate linked to lipid molecules, or glycolipids, are common components of biological membranes. Proteins that have covalently linked carbohydrates are called glycoproteins. - Glycoproteins have important functions at the surfaces of cells, they function as receptors for molecular messengers, other cells, pathogens, or drugs. They are also responsible for the familiar A, B. O system of typing blood. Reactions: Reducing sugar "Reducing sugar" meaning that it can serve as a REDUCING AGENT, it can BE OXIDIZED - The silver diamine complex is reduced by glucose to metallic Silver. Glucose is oxidized to gluconic aad. CHOF