<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>
A direct linear function
A direct relationship is linear b/c they go in a straight line.
The direction of the reaction.
The correct answer is D.
Hope this helps, and Brainliest answer would be appreciated!
<span>Sink
A sink is an area where sugars are used or stored; typically, these are the roots and fruits of a plant.</span>
