Isomerism some different arrangements of atoms within a molecule

9 Isomerism some different arrangements of atoms within a molecule 

Remember the athlete who lost his bronze medal Keep reading. 

A11 the molecules of sugars, amino acids, proteins will have optical isomers, because there are many asymmetric carbon atoms in their structures that have four different groups joined to a central carbon atom, but the body is very selective of the type of isomer it can use D-glucose is sweet but its L-isomer is not. The body cells like D-glucose and uses them for cell building and energy sources, but they hate L-glucose. 

Consider another actual molecule where this property occurs, i.e. lactic acid, CH3C H(OH)COOH. The asterisked carbon atom has four different groups arranged around it (CH3, H, OH and COOH) and so this molecule must be optically active and have two different isomers. We say the starred carbon atom is asymmetric , i.e. not symmetrical. You can draw out the two forms. It is impossible to say which is the d or l form by simply looking at them they must be tested for their twisting properties with polarized light beams. 

Look at this amino acid - NH2CH(CH3)COOH. Can you spot the asymmetric carbon atom Remember, the three-dimensional fruit model can be used. 

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ISOMERISM SOME DIFFERENT ARRANGEMENTS OF ATOMS WITHIN A MOLECULE... 

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