The number of tripeptides formed by three amino acids: glycine, alanine and serine is

Answer

To determine the number of tripeptides that can be formed from three amino acids: glycine (Gly), alanine (Ala), and serine (Ser), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Amino Acids**:
We have three amino acids:
- Glycine (Gly)
- Alanine (Ala)
- Serine (Ser)

2. **Understand the Concept of Tripeptides**:
A tripeptide consists of three amino acids linked together by peptide bonds. The order in which the amino acids are arranged matters, as different sequences will yield different tripeptides.

3. **Calculate the Number of Arrangements**:
Since we have three distinct amino acids, the number of different arrangements (permutations) of these three amino acids can be calculated using the factorial notation. The formula for the number of permutations of n distinct objects is given by n! (n factorial).

Here, n = 3 (the three amino acids: Gly, Ala, Ser).
Therefore, the number of arrangements is:
\[ 3! = 3 \times 2 \times 1 = 6 \]

4. **List All Possible Tripeptides**:
To ensure we have accounted for all combinations, we can list them:
- Gly-Ala-Ser
- Gly-Ser-Ala
- Ala-Gly-Ser
- Ala-Ser-Gly
- Ser-Gly-Ala
- Ser-Ala-Gly

5. **Conclusion**:
Therefore, the total number of distinct tripeptides that can be formed from glycine, alanine, and serine is 6.

### Final Answer:
The number of tripeptides formed by glycine, alanine, and serine is **6**.