Carbohydrates
•Carbohydrates are made from carbon, hydrogen and oxygen. The formula for carbohydrates can be generalised as Cx(H2O)y.
•These molecules can exist in a range of forms, from very small molecules to very large polymers.
•Carbohydrates are commonly found as a group of chemicals known as saccharides.
•There are three types of saccharides. They are monosaccharides, disaccharides and polysaccharides.
•These molecules can exist in a range of forms, from very small molecules to very large polymers.
•Carbohydrates are commonly found as a group of chemicals known as saccharides.
•There are three types of saccharides. They are monosaccharides, disaccharides and polysaccharides.
Monosaccharides
Monosaccharides are a simple sugar. There are three main types of monosaccharides. They are glucose, fructose and galactose.
These are white crystalline solids that are highly soluble in water. These molecules consist of a number of functional groups. Functional groups are the parts of molecules that affect the properties of the molecule. The hydroxy (-OH) is the functional group present on each of these molecules. Making the molecules polar and therefore highly soluble in water. •Glucose (C6H12O6) is found in all living things. It is the key energy source for most life forms. •Fructose is found mainly in fruit juice and honey. It is 1.7 times sweeter than table sugar. It use in the body is similar to glucose in that it is a major energy source. • Galactose is not found as a free molecule in nature. •The above three monosaccharides are all the building blocks for other types of saccharides, eg disaccharides and polysaccharides. DisaccharidesDisaccharides are formed when 2 monosaccharides undergo a condensation reaction.
•The diagram on the right shows the equation for the condensation reaction. In this reaction, as with all condensation reactions, water is produced. The only change to the structures of the reactants is in the linkage between the two monosaccharides that for the disaccharide. The link is called a glycosidic (or ether) linkage. •There are three important disaccharides. They are Maltose, lactose and sucrose. •Maltose is formed by the condensation of glucose to glucose •Lactose is formed by the condensation of glucose to galactose •Sucrose is formed by the condensation of glucose to fructose PolysaccharidesPolysaccharides - also known as complex carbohydrates.
•They are formed by the polymerisation of the monomer glucose, again by a condensation reaction. They are insoluble in water and tasteless. Three important polysaccharides: •Glycogen •Starch •Cellulose Glycogen: Animals store energy in the body. One of the methods used to store energy is to convert excess glucose in the body into the polymer glycogen. The glycogen is stored in muscle and body tissue, and when required converted back into glucose ready to be turned into energy. Starch: Plants store glucose in the form of starch rather than glycogen. Cellulose - is another form of the polysaccharides. This particular type varies in the orientation of the components in the polymer. It is not readily broken down into the glucose monomer and so not easily used as a source of energy. It is important in keeping our digestive system regular. Cellulose is referred to as dietary fibre or roughage. Glycogen and starch are energy storers. Single branched strand of glucose in a glycogen molecule By CeresVesta at English Wikipedia - Transferred from en.wikipedia to Commons., Public Domain, https://commons.wikimedia.org/w/index.php?curid=53007229
|
Monosaccharides diagram By OpenStax College - Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun 19, 2013., CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=30131152
Condensation reaction diagram By OpenStax synthesis of biomolecules Download for free at http://cnx.org/contents/ea44b8fa-e7a2-4360-ad34-ac081bcf104f@12.
Disaccharides diagram By OpenStax Anatomy and Physiology - https://cnx.org/contents/[email protected]:fEI3C8Ot@10/Preface, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=49891316
Triple strand of cellulose showing hydrogen bonding between the glucose molecules By CeresVesta (talk) (Uploads) - Own work, Public Domain, https://en.wikipedia.org/w/index.php?curid=24862334
Polysaccharides diagram By OpenStax- Download for free at http://cnx.org/contents/42119086-be31-4267-8a53-59266f2d58af@7.
|