<span>Amino acids are the basic structural unit of all proteins. A 'free' amino acid (a single amino acid) always has:
an amino group -NH2,
a carboxyl group -COOH
a hydrogen -H
a chemical group or side chain -"R".
Since the amino acids (except glycine) have 4 different groups attached to the a-carbon, they are optically active stereoisomers (recall 23.101 Organic Chemistry) although only L-isomers are found in proteins.
At a neutral pH, both the amino and the carboxyl groups are ionised, giving what is termed the zwitterionic</span>
Paraldehyde
It is a central nervous system
depressant and was soon found to be an effective anticonvulsant, hypnotic and
sedative. Paraldehyde has a hot burning taste and can upset the stomach. It is
often mixed with milk or fruit juice in a glass cup and stirred with a metal
spoon.
its c at the end of meiosis each gamete has two full sets of chromosomes
