My Favorite Cycle Of Pain And Suffering

Every biochem and physics student knows that pain. Top image shows the Krebs cycle (aka citric acid cycle) with its maddening array of enzymes and intermediates that powers cellular respiration. Bottom shows the Carnot cycle, that thermodynamic nightmare with isothermal and adiabatic processes that engineering students memorize while crying into their coffee.

The monkey's expression perfectly captures that moment when your professor says "this will definitely be on the exam" and your brain just shuts down. The "neuron activation" part is the brief moment of clarity before realizing you still don't understand either cycle.

Fun fact: The Krebs cycle produces just 2 ATP molecules directly but sets up the electron transport chain to make about 34 more. That's efficiency that would make even a thermodynamics professor proud!