If you're seeing this message, it means we're having trouble loading external resources for Khan Academy.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.


7 videos
1 skill
5D: DNA makes RNA, and RNA makes proteins,, which are one of the most important biomolecules of our bodies. They are comprised of even smaller amino acids, which are held together by peptide bonds to form proteins. You will discover the structure and functions of proteins at the cellular level in this tutorial.

Amino acid structure

VIDEO 10:55 minutes
In this video, you'll learn about the general structure of amino acids, which include an amine group, a carboxylic acid group, and a unique side chain (R-group) attached to the alpha carbon. In addition, we'll explore where amino acids fit ...

Classification of amino acids

VIDEO 6:06 minutes
Amino acids can be classified according to their side chain's chemical properties (the R-group). This video will show you how! By Tracy Kovach.

Peptide bonds: Formation and cleavage

VIDEO 7:11 minutes
Peptide bonds are formed when the amine group of one amino acid binds with the carbonyl carbon of another amino acid. We will learn more about peptide bonds and how the cleaving process occurs.  By Tracy Kovach.

Four levels of protein structure

VIDEO 8:49 minutes
The four levels of protein structure are primary, secondary, tertiary, and quaternary. It is helpful to understand the nature and function of each level of protein structure in order to fully understand how a protein works.  By Tracy ...

Amino acids and proteins quiz

Amino acids and proteins quiz