Answer:
A substrate is a molecule acted upon by an enzyme. A substrate is loaded into the active site of the enzyme, or the place that allows weak bonds to be formed between the two molecules. An enzyme substrate complex is formed, and the forces exerted on the substrate by the enzyme cause it to react, and become the product of the intended reaction. The bonds that form between the substrate and enzyme cause the confrontational change, or shape change, in the enzyme. The resulting shape change is what applies pressure to the substrate, either forcing molecules together or tearing them apart.