Question

How many different tripeptides can be formed by lysine and alanine?

Short answer

Eight different tripeptides can be formed by the amino acids lysine and alanine.

Step-by-step solution

Understand the Terms

A peptide is a molecule composed of two or more amino acids. Tripeptides are those peptides which are composed of three amino acids. Here, the given amino acids are lysine and alanine. Since repetition is allowed, each of the three positions in the tripeptide can be either of lysine or alanine.

Calculate Permutations

To calculate the permutation, each of the three positions in the tripeptide can have one of two options, alanine or lysine, hence the total permutations would be \(2^3\). The base, 2, represents the number of choices for amino acids, and the exponent, 3, the number of positions in a tripeptide.

Final Calculation

\[2^3 = 2*2*2 = 8\].Therefore, eight different tripeptides can be formed by the amino acids lysine and alanine.