Biology Fermentation Practical
"A comparison of the respiration of yeast in different sugar substrates"
Aim: The aim was to compare the respiration of yeast in different substrates of sugars, i.e. between a monosaccharide (glucose) and a disaccharide (maltose)
Theory: There are three types of Carbohydrates, monosaccharides, disaccharides, and polysaccharides. The two, which I will be looking at, are, monosaccharide (glucose) and the disaccharide (maltose)
Classification and major properties of carbohydrates
Monosaccharides general formula:(CH20)n(n = 3 to 0)Small molecules with low molecular mass; sweet tasting; crystalline; readily soluble in water.Trioses, e.g. glyceraldehyde (C3H603)Hexoses e.g. glucose, fructose (C6H12O6)
Disaccharides general formula:2[(CH2O)n] - H2OSmall molecules with low molecular mass; sweet tasting; crystalline; soluble in water, but less readily than monosaccharides.Sucrose, maltose, lactose, all with the general formula C12H22O11
From the above you can already see the differences in the properties, between the monosaccharide and the disaccharide. The disaccharides are soluble but "less readily than monosaccharides."
Monosaccharides contain carbon, hydrogen and oxygen, in the ration 1 : 2 : 1, so their general formula becomes (CH2O)n, where n an be any number between 3 and 9. All monosaccharides also contain C=O (carbonyl) group and at least two OH (hydroxyl) groups. These two groups of atoms within the molecule are called reactive groups and play important roles in the reactions that take place within the cells.
All the sugars that occur naturally are derived from trioses. All the aldoses are formed from glyceraldehydes and all the ketones from dihydroxyacetone.
Glucose can exist in two different ring forms: one where the hydroxyl group on carbon-1 is below the ring (ÃÂ¡-glucose) and one where the hydroxyl group is above the ring (ÃÂ¢-glucose). These are known as ÃÂ¡- and ÃÂ¢-isomers, and, because the atoms and groups are arranged differently in space, are examples of...