Cellular respiration: glycolysis, fermentation, aerobic respiration and the respiratory balance sheet
This course follows the chapter on respiration in plants, from why organisms need energy and how plants exchange gases, through glycolysis, fermentation, aerobic respiration, the electron transport system and oxidative phosphorylation, to the respiratory balance sheet, the amphibolic pathway and the respiratory quotient. It is built entirely from the supplied document, using its terminology and order of ideas.
The lessons are arranged as a connected sequence. Full lesson content and assessments can be generated and published separately.
The chapter opens by connecting breathing to the release of energy from food, and explains that all energy for life processes is obtained by oxidation of macromolecules called food.
This lesson defines respiration as the breaking of C-C bonds of complex compounds through oxidation within cells, introduces respiratory substrates, and explains why energy is trapped as ATP rather than released in one step.
The lesson answers the question of whether plants breathe, explaining that plants require O2 and give out CO2 but have no specialised organs for gaseous exchange, using stomata and lenticels instead.
This lesson explains why diffusion distances are short even in large plants, and contrasts the complete combustion of glucose with the cell's strategy of oxidising glucose in several small steps coupled to ATP synthesis.
The lesson considers cells and organisms living where oxygen may or may not be available, distinguishes facultative from obligate anaerobes, and introduces glycolysis as the breakdown of glucose to pyruvic acid without oxygen.
This lesson covers the origin of the term glycolysis, the scientists who gave the scheme, its location in the cytoplasm, and the conversion of sucrose into glucose and fructose before entry into the pathway.
This lesson follows the ten reactions of glycolysis, noting where ATP is used and where ATP and NADH + H+ are formed, and introduces the three major ways cells handle pyruvic acid.
This lesson describes fermentation under anaerobic conditions, the conversion of pyruvic acid to CO2 and ethanol by yeast, the production of lactic acid by some bacteria and in animal muscles, and the small energy yield.
This lesson explains why organisms carry out complete oxidation of glucose, introduces aerobic respiration in the mitochondria, and describes the oxidative decarboxylation of pyruvate to acetyl CoA.
This lesson follows the Krebs' cycle from the condensation of acetyl group with oxaloacetic acid to citric acid, through decarboxylations and oxidations, noting GTP, NADH + H+ and FADH2 formation.
This lesson explains how NADH + H+ and FADH2 are oxidised through the electron transport system on the inner mitochondrial membrane, how electrons pass through complexes I to IV to oxygen, and how ATP is synthesised by ATP synthase.
This lesson describes ATP synthase (complex V) with its F1 and F0 components, the passage of protons through F0 coupled to ATP synthesis at F1, and the chemiosmotic hypothesis.
This lesson presents the assumptions used to calculate net ATP gain, explains why they are not really valid in a living system, and states the net gain of 38 ATP molecules during aerobic respiration of one glucose molecule.
This lesson explains how fats, glycerol and proteins enter the respiratory pathway at different points, and why the respiratory pathway is better considered amphibolic rather than only catabolic.
This lesson defines the respiratory quotient as the ratio of the volume of CO2 evolved to the volume of O2 consumed, and gives its values for carbohydrates, fats and proteins.
Use the lesson order as your study path, then return to the matching quiz focus before moving ahead.
Work through the lessons in sequence, or jump directly to the topic you need.