AQA A-Level Chemistry Amino Acids, Proteins + DNA

Amino Acids,
Proteins, and
DNA

, ZWITTERIONS:
Amino Acids Ions that have both a permanent
negative charge, though the compo
- Have 2 functional groups (an amine overall.
and a carboxylic acid) The carboxylic acid group has a ten
- 20 important naturally occurring a proton (produce the negative ch
amino acids and all exist as a-amino amine group has the tendency t
acids proton (produce the positive
- Chiral molecule The ionic interaction between z
- Almost all naturally occurring amino explains the relatively high meltin
acids exist as the - enantiomer amino acids as opposed to the wea
bonding that would occur in the no

Acid:
In strongly acidic conditions, the lone pair of the H2-N
group accepts a proton to form a positive ion
The amino group has gained a hydrogen ion – it is
protonated.

Alkali:
In strongly alkali conditions, the –OH group loses a
proton to form the negative ion.
The carboxylic acid group has lost a hydrogen ion – it is Isoelectric Point – the pH at which a molecule
deprotonated. net electrical charge or is electrically neutral.