2.2.a Describe the ring forms of α-glucose and β-glucose. 

• Glucose is sugar called monosaccharide containing carbon atoms.
• All sugars have names ending with ‘-ose’. 
• Sugars are classified by the number of carbon atoms present. 
• A monosaccharide containing 3 carbons is called a triose, containing 5 carbons is called a pentose, and containing 6 carbons is called a hexose.
• Glucose, fructose and galactose are examples of hexoses.
• Glucose forms a ring structure containing oxygen and six carbon atoms.  
• There are two kinds of glucose ring forms (isomers of glucose) known as ‘α-glucose’ and ‘β-glucose’. 
• In α-glucose, the hydroxyl group (-OH) is below the ring plane. 
• In β-glucose, the hydroxyl group (-OH)  is above the ring plane.

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 References: 

• Jones, M., & Parkin, M. (2018). Cambridge International AS and A Level Biology. Cambridge: Cambridge University Press.
• Tlamjs. (2017, January 17). Biological Molecules: Carbohydrates. Retrieved from https://tlamjs.com/2017/01/13/biological-molecules-carbohydrates/