How many different combinations are possible for a tetrapeptide containing two glycines (Gly,) one alanine (Ala,) and one phenylalanine (Phe)?

Question

Quizplus · Accepted Answer

There are 12 possible combinations for a tetrapeptide containing two glycines, one alanine, and one phenylalanine. This is because the order of the amino acids in the peptide can be varied. For example, the following are all possible combinations:Gly-Gly-Ala-PheGly-Gly-Phe-AlaGly-Ala-Gly-PheGly-Ala-Phe-GlyAla-Gly-Gly-PheAla-Gly-Phe-GlyPhe-Gly-Gly-AlaPhe-Gly-Ala-GlyPhe-Ala-Gly-GlyPhe-Ala-Gly-GlyAla-Phe-Gly-GlyAla-Phe-Gly-Gly

How Many Different Combinations Are Possible for a Tetrapeptide Containing