Sugars

• Amylose is a long, unbranched chain of alpha glucose. It has 1-4 gylcosidic bonds. and is found in starch. The angles of the glycosidic bonds give it a coiled structure almost like a cylinder.So its really good for storage because you can fit more in to a small space.
• Amylopectin is a long branched chain of alpha glucose. Its side branches allow the enzymes that break down the molecule to get at the glycosidic bonds easily. This means glucose can be released quickly. Amylopectin contains 1-4 and 1-6 glycosidic bonds.
• Plants store excess glucose as starch. When the plant needs more glucose energy it breaks down starch to release the glucose. Starch is a mixture of two polysaccharides of alpha glucose amylose and amylopectin.
• Cellulose is made up of beta glucose units joined by 1-4 glycosidic bonds. Cellulose forms microfibrils which are bundles of cellulose chains held together with hydrogen bonds between adjacent chains. These fibrils form macrofibrils which are then arranged into fibres. They have a very high tensile strength so they make great structural material
• Starch is insoluble in water and doesnt effect water potential so it doesnt cause water to enter cells by osmosis which would cause swelling.This makes it good for storage.
• Animals store excess glucose as glycogen which is another polysaccharide of alpha glucose.Its structure is very simliar to amylopectin except it has more side branches so that glucose can be released very quickly. It is also a very compact molecule and so its good for storage.
• Glycogen is soluble in water so when an animal needs more glucose energy it dissolves some glycogen and releases the glucose. Glycogen causes water to enter cells by osmosis which causes them to swell slightly. This allows the muscle cells to contract better during exercise. Glycogen has 1-4 and 1-6 glycosidic bonds.
• Cellulose is made of long, unbranched chains of beta glucose. When beta glucose molecules bond they form straight cellulose chains. The cellulose chains are linked together with hydrogen bonds to form strong fibres called microfibrils. This gives cellulose structural support for cells.
• All carbohydrates contains the elements carbon hydrogen and oxygen. Carbohydrates are made out of monosaccharides. Glucose is a hexose sugar - a monosaccharide with six carbon atoms in each molecule. There are two types of glucose alpha glucose and beta glucose. they are isomers ( molecules with the same molecular formula but atoms connected in a different way)
• A disaccharide is formed when two monosaccharides join together. Monosaccharides are joined together by condensation reaction. A glycosidic bond is formed between the two monosaccharides as a molecule of water is released.
• The most common disaccharide is sucrose. Its made up of one molecule of alpha glucose and one molecule of fructose
• Lactose is another diassacharide formed from alpha glucose and a galactose molecule.
• Reducing sugars include all monosaccharides and some disaccharides. You add benedicts reagent and heat in a water bath that has been brought to a boil. If the test is posotive it will produce a coloured precipitate if the sample remains blue then there is no reducing sugaers present.
• If the result of a reducing sugar is negative there could still e a chance that a non-reducing sugar is present. To test for non reducing sugars you have to break them down into monosacharrides. You do this by add dilute HCl to the solution and bringing to a boil. Then you neutralise by adding sodium hydrogencarbonate finally carry out the benedicts test as normal.
• Maltose is made up of two alpha glucose monosaccharides.
• To test for starch, add iodine dissolved in potassium iodide to the sample. If starch is present the sample will turn from orangey-brown to a dark blue-black.