How many peptide linkages are there in a nano peptide?

8

The correct answer is option 2.  8.

A nanopeptide is a short peptide consisting of between 10 and 100 amino acids.

A peptide linkage, also known as a peptide bond, is the covalent bond formed between the carboxyl group \((-COOH)\) of one amino acid and the amino group \((-NH_2)\) of another amino acid.

Each peptide bond connects one amino acid to the next along the peptide chain.

Calculating Peptide Linkages in a Nanopeptide:

In a nanopeptide with 9 amino acids:

The first amino acid has a free amino group \((-NH_2)\).

The last amino acid has a free carboxyl group \((-COOH)\).

Between each pair of adjacent amino acids, there is one peptide bond.

Therefore, if a nanopeptide contains 9 amino acids, there will be 8 peptide linkages (peptide bonds):

The first amino acid contributes its carboxyl group to form the first peptide bond.

Each subsequent amino acid contributes its amino group to form a peptide bond with the carboxyl group of the preceding amino acid.

Conclusion:

Based on the definition of a nanopeptide and the structure of peptide bonds, a nanopeptide with 9 amino acids will contain 8 peptide linkages. Each linkage represents the covalent bond between successive amino acids in the peptide chain. Hence, the correct answer remains: 8.