Glucose C6H12O6
Glucose is a hexose sugar with 6 carbon atoms and is soluble in water, making it hydrophilic. The structure of glucose includes an OH group on each carbon. There are two forms of glucose: alpha glucose and beta glucose, and fructose and galactose are also examples of monosaccharides.
Disaccharides
Disaccharides are formed when two monosaccharides bond together. The OH groups on the glucose molecules form hydrogen bonds with water molecules. For example, alpha glucose and alpha glucose combine to form maltose, while glucose and fructose form sucrose, and glucose and galactose form lactose.
Amylopectin
Amylopectin is a polymer of alpha glucose molecules and is insoluble in water, so it does not affect water potential. It consists of branches with a hydroxyl group on carbon 1 that points above the plane of the ring, which is characteristic of alpha glucose. Amylopectin is broken down by enzymes that act at the ends of the branches, and its branches mean enzymes can break it down quicker.
Polysaccharides
Starch is made up of alpha glucose molecules and is insoluble in water, while cellulose is a polymer of beta glucose. Every 2nd molecule of cellulose flips to change its size. Another type of polysaccharide, amylose, consists of unbranched alpha glucose molecules that twist into a compact helix and can store a large amount of glucose.
Different Structures of Carbohydrates
Carbohydrates have different structures, including monosaccharides, disaccharides, and polysaccharides. Monosaccharides are hydrophilic and can affect water potential. They are the building blocks of carbohydrates and include examples like glucose, fructose, and galactose, among others.
Carbohydrates play a crucial role in biological molecules, and understanding their structures and functions is fundamental in the field of biology. This knowledge is essential for students studying at the OCR A level, especially when preparing for the biological molecules exam and answering questions related to carbohydrates.
