BIOCHEMISTRY 1. explain carbohydrate nonmenclature (aldose vs. ketose and number of carbons, numbering of carbons), including characterizations of chirality (optical isomers, enantiomers, diastereomers, and epimers) 2.identify common and important disaccarides 3.distinguish all structural and biochemical similarities and differences between starch, cellulose, and glycogen 4.what are fat soluble vitamins and what are their roles in the body Solution 1. The monosaccharides are the simple sugar molecules with general formula (CH2O) n. They are mainly composed of Carbon, Hydrogen and Oxygen. Monosaccharides possess functional groups such as aldehydes and ketones in their structure. Basing on the functional group present they are named as aldose - that contains an aldehyde group, ketose - that contains a ketone group. They also contain many hydroxyl groups. Hence, monosaccharides are called as polyhydroxy aldehydes or polyhydroxy ketones. A Hexose having ketone group is known as Ketohexose. Fructose is an example of ketohexose. . Hexose with an aldehyde group is called as Aldohexose. Example of an Aldohexose is Glucose. A Triose is a monosaccharide having three carbon atoms in its skeleton. Glyceraldehyde is an example of a triose.A Pentose is a monosaccharide having five carbon atoms in its structure. Ribose is an example of a pentose. Both triose and pentose are monosaccharides differing in number of carbon atoms in their skeleton. The molecules having a Carbon atom bonded to four different functional groups are called ‘chiral molecules’. The center carbon atom is called chiral carbon. Any molecule having a chiral carbon exists in a pair of enantiomers, which are nonsuperimposable mirror images. Stereo isomers are the molecules having same molecular formula and same bonding but differ in spatial arrangement of atoms. They are mirror images. They rotate the plane polarized light either to clockwise or to counter clockwise. If they rotate the plane polarized light to clockwise, they are called as ‘dextro rotatory’ (D forms) and are indicated by (+) sign. If they rotate the plane polarized light to counter clockwise, they are called as ‘levo rotatory’ (L forms) and are indicated by (-) sign. Diastereomers can be defined as a pair of stereo isomers that are not enantiomers. This indicates that the isomers are not mirror images and they totally differ from each other. Enantiomers though nonsuperimposable mirror images they have same physical and chemical properties, they differ only in rotation of plane polarized light. Diastereomers have different physical and chemical properties. 2. The disaccharides are composed of two monosaccharide units. Maltose, Lactose and Sucrose are the examples of disaccharides. These are referred by their common names like, Malt sugar, Milk sugar and Table sugar. Galactose is a hexose molecule. It is one of the components of disaccharide Lactose or milk sugar. It is found in the milk of mammals. -D - N - acetylgalactosami.