Imagine that you are a cell and you want to join two low energy molecules together. They resist joining. What two special types of molecules would you need to supply to overcome this obstacle?
An enzyme is the term that is used for the catalysts in the living system which work to lower the activation energy of a reaction and hence, accelerate the rate at which the chemical reactions can occur.
ATP is an organic molecule - Adenosine triphosphate which is responsible for providing energy to drive different processes in the living organisms, and thus, is also known as the energy currency of the cell.
In the given case, the molecules that are to be joined have low energy and a resistance to come together, in such a situation the ATP will provide the energy for the molecules to come together and the enzymes will help orient the molecules in a suitable manner and accelerate the rate of reaction to ultimately join them.