Question

.Below is the generic formula for an amino acid, one of the building blocks for proteins. 'R' stands for a variable functional group which is different in each type of amino acid. The rest of the molecule's structure is common to all of the amino acids. R Ι 0 - Ι OH I 1. Identify one place where an amino acid has a non-polar covalent bond 2. Identify one place where amino acids have a polar covalent bond Do you think amino acid monomers would dissolve in water? Yes No Maybe (why?)

Answer 1

1.

  Non-polar covalent bonds are very strong bonds. The electrons in the adjacent atoms are shared equally, which means that there is no push/pull effect .

Example of non-polar covalent bond here is

C-H bond.

2.

polar covalent bond is still very strong, but the electron sharing between the atoms is unequal. One atom is able to pull more strongly on the electrons than the other, so that the part of the molecule which pulls the electrons towards it is relatively negatively charged while the other part of the molecule which has had the electrons pulled away from it is relatively positively charged.

Example of polar covalent bond here is C-C and

C-N bond.

3.

Amino acids are generally soluble in water and insoluble in non-polar organic solvents such as hydrocarbons. This again reflects the presence of the zwitterions. In water, the ionic attractions between the ions in the solid amino acid are replaced by strong attractions between polar water molecules and the zwitterions.