Re: Enzymes, _sophiestudies_ Answer is really good!
I’d suggest that we don’t really need to know anything more complex than this for VCE - but I think I know what you are talking about with the whole ‘bringing reactants together’.
I believe there is a khan academy video where he talked about the reaction between an Alkene and water. (An Alkene being a carbon chain with a Carbon=Carbon double bond in the middle)
The enzyme/catalyst moves or bends the hydrogens away from the double bond - allowing for the water molecule to attack it (performing a nucleophilic attack). This - without the catalyst - is harder; because the hydrogens would get in the way of the water molecule. This is called a hydration/addition reaction in Chem.
While you don’t need to know that for bio - I found it quite interesting last year.
Another example is that of ATP synthase. It acts like a windmill - using the flow of H+ ions to provide energy to attach a phosphate group to ADP - forming ATP.
So overall, perhaps:
An enzyme lowers activation energy by stimulating conditions favourable to the reaction - and weakening intramolecular forces.
