Question

How many tripeptides are possible when following three amino acids make tripeptide? (No amino acid should repeat twice) 
(A) Glycine 
(B) Alanine 
(C) Valine 
 

• A. 4
• B. 6
• C. 8
• D. 9

Hint:

Peptide sequences are counted using permutations, not combinations.

Answer 1

The Correct Option is B

To solve this problem, we need to determine the number of unique tripeptides possible when we have three different amino acids: Glycine (Gly), Alanine (Ala), and Valine (Val). A tripeptide consists of three amino acids linked together in a specific sequence, and no amino acid is repeated within the same tripeptide.

The number of permutations of n distinct items is given by n! (factorial of n). Since we have three different amino acids, the total number of permutations is 3!.

Let's calculate 3!:

3! = 3 \times 2 \times 1 = 6

Therefore, there are 6 possible unique tripeptides that can be formed. Each permutation represents a different sequence of the three amino acids.

The possible tripeptides are:

• Gly-Ala-Val
• Gly-Val-Ala
• Ala-Gly-Val
• Ala-Val-Gly
• Val-Gly-Ala
• Val-Ala-Gly

Thus, the correct answer is 6, which is consistent with the provided correct option.