Give reason for the following : (i) Amino acids have high melting points and are soluble in water. (ii) What is meant by the secondary structure of proteins ?

Give reason for the following : (i) Amino acids have high melting poin

1.	Give reason for the following : (i) Amino acids have high melting points and are soluble in water. (ii) What is meant by the secondary structure of proteins ?
Answer» Solution :(i) `alpha`-Amino acids contain both an acidic carboxyl group and a BASIC amino group. These two GROUPS neutralize each other. As a result, `alpha`-amino acids largely exist as dipolar ions or zwitterions. `NH_(2)-underset(R)underset(\|)CH-COOHhArroverset(+)NH_(3) -underset("Zwitterion")underset(R)underset(\|)(CH)-COO^(-)` Due to dipole interactions , the molecules of `alpha`-amino acids are HELD together by STRONG forces of attraction and hence amino acids have hight melting points. Further , due to strong interactions between the `+ve` and `-ve` poles of `alpha`-amino acids with molecules , `alpha`-amino acids are moderately soluble in water. (ii) Secondary structure of proteins refers to the conformation or the shape which the polypeptide chains Assume as a result of H-bonding . there are two types of secondary structures of proteins. These are `alpha`-helix and `beta`-PLEATED sheet structure.