Question

About how many typical amino acids are found in proteins?

Answer 1

Hint: Amino acids are structural or building blocks of proteins. They are monomers, which combine to form proteins. When the proteins are broken down or digested, amino acids are left. They are principally organic compounds, which are made up of the amino group, carboxylic group, and a side chain, which is specific to each amino acid. The key elements of amino acids are nitrogen, oxygen, carbon, and hydrogen.

Complete answer:

                                            Fig: Constitution of Protein by Amino Acids
As of $1983$, there are $500$ naturally occurring amino acids, though only $20$ amino acids appear in the genetic code.
There is no boundary for the number of amino acids which can compose a protein. Protein has enough amino acids in it to attain a relatively stable conformation.
Protein signalling molecules like cytokine may have forty amino acids. The chain of amino acids, which are too small compared to protein, is called polypeptide.
Also, there is no upper boundary for protein size. A mid-size kinase, which is a standard globular protein, has $1200$ residues.
Depending on the number of amino acids, the linear structure can be distinguished into a polypeptide chain and protein. If more than $50$ amino acids are present, the linear structure is named protein, otherwise, it is called a polypeptide chain. If only $20$ amino acids are present, then it is called a peptide.
Trp-cage is a smaller protein, which is derived from the saliva of Gila monsters. It consists of only $20$ amino acids. Titin is the largest known protein, containing more than $34000$ amino acids.

Note:
As long as the protein folds into a stable form after synthesis, the number of amino acids present in a protein is endless. The length of the protein is dependent on the length of RNA, which is synthesized from DNA. A codon of three nucleotides of RNA encodes an amino acid. Even, several smaller proteins join together to form a bigger protein. However, in the human body, only $20$ amino acids make up the proteins.