Does Nature use only 20 amino acids?

Does Nature use only 20 amino acids?
How the experimental verification of the genetic code was accomplished
Countless scientists contributed to its clarification with brilliance, ingenuity, intuition, and luck
An inspirational example of not letting obstacles discourage you, but using them as stepping stones instead
The Nobel Prize in Physiology or Medicine in 1953 and Krebs' thoughts about life as a displaced person
The life of the discoverer of the citric acid and urea cycles from 1933 to 1981
Discoverer of the citric acid and urea cycles forced to leave Nazi Germany in 1933
Does everybody's urine smell after eating asparagus?
How does asparus change when it is cooked?
Why does asparagus produce odorous compounds?