Anaerobic respiration

• Anaerobic respiration is respiration in the absence of oxygen, which only occurs in the cytoplasm of the cell.
• Unlike aerobic respiration, where the majority of the stages occur in the mitochondria, anaerobic respiration only occurs in the cytoplasm.
• For plants, microbes, and animals, anaerobic respiration begins with glycolysis, which creates pyruvate.
• In plants and microbes, the pyruvate is converted into lactate, while in animals, it is converted into lactate.
• The purpose of anaerobic respiration is to release small amounts of ATP, but the key is to oxidize NAD, so that NAD can be used in glycolysis again and again, even in the absence of oxygen.
• In plants, microbes, and animals, glycolysis begins with the conversion of glucose into pyruvate, and the next step is for pyruvate to gain a hydrogen, reducing it to lactate.
• The net gain of ATP from glycolysis is two, and the purpose of this stage is to re-oxidize NAD, so that NAD can then be used again in glycolysis, allowing anaerobic respiration to continue even in the absence of oxygen.
• Lactate is an acid that will eventually denature enzymes, preventing anaerobic respiration from occurring indefinitely.
• In plants and microbes, the stage of glycolysis that results in the production of ethanol and carbon dioxide is the same as the stage that results in the production of ATP.
• The conversion of pyruvate to lactate is necessary to re-oxidize NADH into NAD so that glycolysis can continue.
• Anaerobic respiration is even less efficient than aerobic respiration because from one glucose molecule, only two ATP molecules are produced in glycolysis.
• From one molecule of glucose, aerobic respiration should be able to produce 38 molecules of ATP, but due to inefficiencies, it only produces 32 molecules of ATP.
• ATP has to be used to actively transport pyruvate and reduced NAD into the matrix in oxidative phosphorylation.
• Some of the energy is lost as heat in oxidative phosphorylation, which is why it is only 32 efficient.
• Even in the absence of oxygen for a short period of time, anaerobic respiration can still occur and produce small amounts of ATP.
• In oxidative phosphorylation, protons are meant to be moving through the ATP synthase by facilitated diffusion, but some can leak across the mitochondrial membrane.
• The efficiency of anaerobic respiration is lower than that of aerobic respiration due to the loss of energy as heat and the inability of protons to move through the ATP synthase by facilitated diffusion.