How many tripeptides containing one residue each of L-alanine,L-valine,and glycine are possible?

Question

Quizplus · Accepted Answer

A tripeptide is composed of three amino acids. Since we know one of each type of amino acid (L-alanine, L-valine, and glycine) is required, we just need to figure out how many combinations of those three amino acids are possible. We can simply multiply the number of possible amino acids in each position to find the overall number of combinations:

1st position: 1 (L-alanine) 
2nd position: 1 (L-valine) 
3rd position: 1 (glycine)

Total number of tripeptide combinations = 1 x 1 x 1 = 1

Therefore, there is only 1 unique tripeptide that contains one residue each of L-alanine, L-valine, and glycine. However, we can arrange the amino acids in different orders: 
- L-alanine, L-valine, glycine
- L-alanine, glycine, L-valine
- L-valine, L-alanine, glycine
- L-valine, glycine, L-alanine
- glycine, L-alanine, L-valine
- glycine, L-valine, L-alanine

This gives us a total of 6 possible tripeptides.

Therefore, the best answer choice is D (6).

How Many Tripeptides Containing One Residue Each of L-Alanine,L-Valine,and Glycine