How many different amino acids are responsible for making up the thousands of different proteins found in a cell?
3
15
thousands
4
20

20 amino acids.

Explanation:

Amino acids are the monomers that combine together to form a protein. Two main types of amino acids are non- essential amino acids and essential amino acids.

Thousands of different proteins can be made by the simple 20 amino acids present in the cell. The amino acids can combine in different ways to form all the proteins present in the body.

Thus, the correct answer is option (5).

a physical change is being made.