Question

what is the theoretical number of chemically different dipeptides that may be assembled from two amino acids
1. one
2. two
3. three
4. four ​

Answer 1

Dipeptide = two amino acids connected by amide linkage.

Two amino acids can be selected out of these 20 amino acids without any restriction.

The number of ways first amino acid can be chose out of 20 = 20

Number of ways in which second amino acid can be chosen is again 20.

Total number of choosing randomly to make a dipeptide= 20x20=400  

If question was that you are given only these 20 amino acid molecules (i.e. You have just 20 different molecules) and you have to make dipeptide out of these available amino acids then…

Ways for chosing first amino acid= 20 (as any one out of 20 can be taken)

then number of ways to select second= 19 (as one less is there now due to above selection)

Total number of ways now= 20x19= 380

Answer 2

4. Four is the theoretical number of chemically different dipeptides that may be assembled from two amino acids.

Explanation:

• A dipeptide is an organic compound formed when a peptide bond joins two amino acids.
• Four dipeptides can be formed from two different amino acids depending on which groups are involved in the peptide bond.
• Proteins are formed in a condensation reaction when amino acid molecules join together and a water molecule is removed.
• The new bond formed in protein molecules where amino acids have joined is called an amide link or a peptide link.