Enzyme

2. A chemical reaction that absorbs energy from the surroundings to build chemical bonds (products have more energy than reactants).
5. The starting material in a chemical reaction; in enzyme catalysis, this is specifically called the substrate.
7. The sum of all the chemical reactions occurring in a living cell.
10. The initial energy required to start a chemical reaction, even if it is exergonic.
12. The process of breaking down large molecules into smaller ones, releasing free energy.

1. A model of enzyme activity describing a flexible active site that changes shape to fit the substrate after binding.
3. A model of enzyme activity describing the active site as having a fixed shape that perfectly matches the substrate
4. The substance(s) formed as a result of a chemical or enzyme-catalysed reaction.
6. An organic cofactor (non-protein molecule), such as vitamins or NAD⁺, required by some enzymes to function.
8. Describes reactions that build larger molecules from smaller ones (synthesis), typically requiring energy.
9. A chemical reaction that has a net release of free energy ( reactants have more energy than products).
11. Molecules that reduce or stop an enzyme from functioning (e.g., competitive and noncompetitive inhibitors).