Crash Course Biology #7: In which Hank does some push ups for science and describes the "economy" of cellular respiration and the various processes whereby our bodies create energy in the form of ATP.

Paul Andersen explains how enzymes are used to break down substrates. The correct shape of the active site allows a key/lock fit between the enzyme and the substrate. The enzyme catalase is used to break down hydrogen peroxide. The importance of cofactors and coenzymes is emphasized. Competitive and allosteric inhibition is also included.