Question

Where do the competitive and non competitive enzymes come from? Is it the product from negative feedback?

Answer 1

Inhibitors are small molecules (usually) which bind to the enzyme and essentially 'lock' it in a catalytically inactive conformation.

Competitive inhibitors bind to the enzyme at the its active site. That is, they 'compete' with the reactant molecules for the binding site and once bound prevent the enzyme from binding its reactants. Non-competitive inhibitors are a little subtler: they bind some other part of the enzyme and essentially lock it in a conformation where it can still bind to the reactants but where it cannot go on to catalyze the reaction.

Enzyme inhibition is sometimes part of a negative feedback loop. For example, if the product of the reaction stimulated production of an inhibitor, the enzyme would be under negative feedback control. Sometimes that's the case; sometimes it isn't.