In this case, given that each amino acid is bonded via the peptidic bond (CONH) for each tetrapeptide we obtain the structures on the attached picture. Take into account that each tetrapeptide has an initial amino side and a ending carboxylic side.
If we observe the outer part of the bread, which contains tiny hole like structure, due to the gas formation inside the bread dough.
In the bread dough rising process, the industries are using the yeast, which makes the gas that separates the protein particles in the bread move apart and makes the dough of the bread rise.
In this reaction, the yeast utilizing the carbohydrate to make a gas namely carbon-di-oxide gas which makes the dough to rise
The iron nail displaces the Cu from the copper sulfate solution. This results in the color of CuSO4's disappearance. Copper is less reactive than iron.