So remember that in step one of beta oxidation, inside the matrix of the mitochondria, we have an enzyme that catalyze the reaction in which we basically oxidize the fatty acid and that helps us generate an Fad H two molecule. Now, what about inside the proxosomes? Well, inside the proxysome, it's this step that takes place. So let's suppose we have some type of very long chain fatty acid. Let's suppose our N value here is 16 or greater so that this entire molecule contains at least 20 carbon atoms. Now, in step one, we basically transform this single bond between carbon number two and three into a double bond.