While there are 20 standard amino acids commonly found in the proteins of living organisms, there are actually many more amino acids that exist in nature.

Here's a breakdown:

* 20 Standard Amino Acids: These are the building blocks of proteins and are encoded by the genetic code. They are essential for life and perform a wide variety of functions in the body.

* Non-Standard Amino Acids: These are amino acids that are not directly encoded by the genetic code. Some are modified forms of the standard amino acids, while others are synthesized by specific enzymes.

Therefore, the answer to your question depends on how you define "contain":

* If you're only considering the standard amino acids used in protein synthesis: There are 20.

* If you consider all amino acids found in living organisms: There are many more, but the exact number is difficult to pin down due to the vast diversity of life and ongoing research.