This app lets chemistry students draw the twenty amino acids for exam practice
Practice Mode - Lets you choose which amino acids you want to practice drawing. You can get help in this mode which reveals the proper structure in case you get stuck.
Sudden Death - Once you feel you're ready, you can try drawing all twenty amino acids without making a mistake. This mode does not provide help.
I love that this app allows you to actually draw out the amino acids compare to other apps that just match between structure and name. The one critique I have would be that I would like it to have more features like the other amino acid apps. Such as data tables with info just for reference purposes, and quizzes for the other properties of the amino acids (such as matching full name to three letter or one letter abbreviation--but if the devs do this, use the keyboard to input, not an answer bank)