What is the exact number of Amino acids in nature?
technically… of course in reality the number is limited
There will be millions of organic compounds that contain amine groups and carboxylic acid groups and so could be called amino acids.
There are about 20-21 amino acids found in nature and many other amino acids(about 500 or so) are artificially synthesised.
There are 21 proteinogenic amino acids (that can form proteins). The 21st is selenocysteine.