Hank explains the Electron Transport Chain stage of cellular respiration. He notes that this stage is the "money maker" because it generates a lot more ATP than any other stage.
Venus gives Arnold a 2-minute lesson on the atom. He makes allusions to inner city life (gangs, the neighborhood, etc.) to explain the different parts of the atom in a highly relatable manner.
Hank walks through the first stage of cellular respiration, Glycolysis, which is the breaking down of glucose. This stage is different from the other stages in that it is an anaerobic process, so it does not require oxygen. This video also covers the inputs and outputs of Glycolysis.
Bill Nye explains that an atom is composed of protons, neutrons, and electrons. Protons and neutrons are found in the nucleus and have a positive and a neutral charge, respectively. Electrons, taking on a negative charge, move around the nucleus. Bill Nye demonstrates that an atom is mostly empty space by illustrating the distance between the nucleus and the electrons.
Hank explains the Bohr Model of an atom. He also discusses the correct and incorrect assumptions Bohr made when presenting the model to the scientific community.