3Foods provide us with calories but they are not the form of energy used by cells. Food is broken down by enzymes in the digestive system to form glucose.Celllular Respiration in the mitochondria forms ATP from these sugars.
4The Chemistry of Respiration energy and mitochondria clip
5Adenosine triphosphate The energy released during respiration is not used directly by cells.Instead it is used to make a molecule called ATP which stores the energy until it is needed.ATP = Adenosine triphosphate
6What does ATP do?ATP supplies energy for all the processes that need it.For example:movementchemical reactionsgrowth.slow twitch/fast twitch investigation
15glucose + OXYGEN carbon dioxide + water + ATP C6H12O6 + O2 ――> CO2 + H2O + ATP
16Aerobic respiration happens in 2 stages: Stage 1 – Glycolysisglyco lysisglucose splittingThis stage occurs in the cytoplasm.
17Glycolysis does not require oxygen In glycolysis, a glucose molecule is broken down into pyruvic acid. This process requires 2 ATP to start the reaction.glucoseseries of enzymecontrolled reactionsenergy released to make 4 ATP(-2ATP+4ATP=2ATP)Net gain of 2ATPpyruvic acidGlycolysis does not require oxygen
19Stage 2 – Breakdown of pyruvic acid The pyruvic acid made in glycolysis (stage1) still contains a lot of energy.It moves into the mitochondria to continue the process.It can only be broken down to release the rest of the energy in the presence of oxygen.
20pyruvic acidenergy released to make largequantity of ATP(~36 molecules)series of reactions, calledThe Kreb Cycle &Electron Transport Chaincarbon dioxide + water
24Summary of ATP production Stage 1 and 2 release all the chemical energy in one molecule of glucose to make a total of 36 ATP molecules.2 molecules ATP from glucose pyruvic acid34 molecules ATP from pyruvic acid carbon dioxide + waterTotal 36 molecules ATP
25Anaerobic Respiration (in animals) anaerobic = in the absence of oxygen
26In low oxygen conditions or during heavy exercise, when not enough oxygen can be supplied, muscle cells swap to anaerobic respiration
27in absence of oxygen pyruvic acid is turned into lactic acid. glucoseglycolysis still happens as it does not require oxygen2 ADP + 2 P2 ATPpyruvic acidin absence of oxygen pyruvic acid is turned into lactic acid.lactic acid
28A build up of lactic acid produces muscle fatigue A build up of lactic acid produces muscle fatigue. Muscle fatigue makes muscles ache and contract less powerfully. A recovery period is needed. During this time more oxygen is taken in to convert the lactic acid back into pyruvic acid again. The volume of oxygen needed is called the oxygen debt.
29Summary oxygen debt e.g. during hard exercise oxygen debt glucosepyruvic acidoxygen debte.g. during hard exerciseoxygen debtrepaid during recovery timelactic acid
30Anaerobic Respiration in plants The same process occurs in plants and yeast in low oxygen conditions, e.g. muddy, flooded soils.
31ethanol + carbon dioxide glucosepyruvic acid2 ADP + 2 P2 ATPglycolysis still happens, producing2 ATP moleculesThis time in absence of oxygen, pyruvic acid is turned into carbon dioxide and ethanolThis is irreversibleethanol + carbon dioxide
32Comparison of aerobic and anaerobic respiration in animalsin plants and yeastOxygen required?yesnoGlycolysis occursATP yield36ATP2ATPGlucose completely broke down?End productsCarbon dioxide and waterLactic acidEthanol and carbon dioxide