Question

You have been given three amino acids in excess
Phenylalanine (P)
Glutamine (Q)
Histidine (R)

All three amino acids are put in a container which already contain some acid and excess of water. How many tripepetides are possible which contain three different amino acids?

Answer 1

Possible combinations are
$P–Q–R$
$P–R–Q$
$Q–P–R$
$Q–R–P$
$R–P–Q$
$R–Q–P$