Glucose

• Carbohydrates are made up of carbon, hydrogen and oxygen.
• Monosaccharides are simple sugars that provide a rapid energy source. For example glucose, galactose and fructose.
• Glucose is a hexose sugar containing 6 carbon atoms. It's highly soluble and is the main source of energy for cells.
• Alpha glucose has the OH group attached below carbon 1 whereas beta glucose has it attached above.
• Pentose is a monosaccharide containing 5 carbon atoms. For example ribose and deoxyribose (constitutes of RNA and DNA).
• Ribose has one H and one OH attached too it's second carbon whereas deoxyribose has two H.
• Maltose (malt sugar) is formed from two a-glucose molecules joined by an alpha 1–4 glycosidic bond.
• Sucrose (table sugar) is formed from a-glucose and fructose joined by a glycosidic bond.
• Lactose (milk sugar) is formed from b-galactose and a-glucose joined by a beta 1–4 glycosidic bond.
• Lactose, maltose and sucrose are disaccharides. Glycogen, cellulose and starch are polysaccharides. Glucose, fructose, galactose and ribose are monosaccharides.
• Polysaccharides are polymers containing many monosaccharides linked by glycosidic bonds formed by condensation reactions.
• Glycosidic bonds in the polysaccharide can be broken to release monosaccharide units for cellular respiration. The glycosidic bond between two glucose units is split by hydrolysis.
• Polysaccharide chains can be straight, helical, coiled or branched.

  There very compact molecules ideal for storing carbohydrates in cells.
• Starch is made up from α-glucose and has two components amylose

  and amylopectin.
• Amylose is composed of straight chains (200-5000 glucose). The

  chain is coiled into a spiral due to the position of the 1,4 glycosidic bonds.
• Amylopectin is a polymer of glucose but it has side branches. It has 1,4 glycosidic bonds and 1,6 glycosidic bonds holding each side branch onto the main chain.
• Amylopectin has a lot of terminal glucose molecules that can be broken off rapidly when energy is needed.
• Glycogen contains many alpha 1–6 glycosidic bonds that produce an

  even more branched structure. It's stored as small granules, particularly in muscles and liver.
• Cellulose is another polysaccharide and is the main part of plant

  cell walls. It's very strong, and prevents cells from bursting when they take in excess water.
• Cellulose consists of long chains of B glucose joined by B 1–4 glycosidic bonds. Chains form rope like microfibrils layered to form a network.
• Cellulose is formed through a condensation reaction. The second glucose molecule is rotated 180° forming a 1,4 glycosidic bond.
• Monosaccharides have the formula (CH2O)n. Triose sugars have the formula C3,H6,O3. Pentose sugars have the formula C5,H10,O5. Hexose sugars have the formula C6,H12,O6.
• Energy is supplied for chemical reactions supplied by ATP. ATP comes from the breakdown of the glucose, using oxygen, in the process of cellular respiration.
• The sugars produced by photosynthesis are rapidly converted into starch which is insoluble and compact but can be broken down rapidly during respiration to release glucose when it is needed.