Glucose + Oxygen  Carbon Dioxide + Water (+38 ATP) CELLULAR RESPIRATION VIDEO: CRASHCOURSE RESPIRATION SUMMARY

Cellular Respiration Overview RESPIRATION is a process in which organic molecules act as fuel They are broken down in stages to release chemical potential energy which is used to make ATP The main fuel for most cells is a carbohydrate, usually glucose The 3 main processes are: 1 – GLYCOLYSIS 2 – KREBS CYCLE 3 – OXIDATIVE PHOSPHORYLATION (The electron transport chain) The overall conversion is: enzymes GLUCOSE + OXYGEN  CARBON DIOXIDE + WATER (+38 ATP) or C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 0 (+38 ATP) GLYCOLYSIS (2 ATP) KREBS CYCLE (2 ATP) OXIDATIVE PHOSPHORYLATION (34 ATP) 36 net gain as 2 ATP used right at the beginning #NOTE: These figures vary slightly depending on the text being used!!!

A.T.P – ADENOSINE TRIPHOSPHATE ATP  ADP + Pi ATP can be broken down into ADP and inorganic phosphate to release energy to drive other chemical reactions ADP + Pi  ATP ADP and inorganic phosphate can be joined to create ATP. This stores energy and allows it to be transported around the cell To make 1 ATP requires 30.7KJ to be stored in the last bond Any reactions that produce less than 30.7KJ can’t store the energy which is then lost as HEAT Any reactions that produce more than 30.7KJ have the excess released as HEAT HELPS KEEP US WARM + WHY ENERGY IS LOST OUT OF FOOD WEBS Catabolic Reaction Hydrolysis Anabolic Reaction Rephosphorylation

GLYCOLYSIS

GLYCOLYSIS LOCATION: CYTOPLASM GLUCOSE  2 x PYRUVATE + 2 ATP + 2 NADH GLYCOLYSIS: USES 2ATP – MAKES 4ATP – NET GAIN 2ATP Glycolysis is the splitting of GLUCOSE (6C) to produce 2 x PYRUVATE (3C) molecules The 6C glucose is phosphorylated then split into 2 triose phosphate molecules (3C) which are then oxidised further to produce the pyruvate, some ATP and reduced NAD NAD can be reduced to NADH - it accepts H+ and transports ions around the cell - the hydrogen can be transferred easily to other molecules Glycolysis is the only part of respiration that USES energy Glycolysis consists of a series of 10 chemical reactions, each controlled by its own enzyme Pyruvate are sent to the mitochondria to be converted via KREBS CYCLE The released Hydrogen is carried away by NAD to be used elsewhere Glycolysis DOES NOT require oxygen

KREBS CYCLE

Transition Reaction & KREBS CYCLE LOCATION: TRANSITION – MITOCHONDRIAL MEMBRANE KREBS CYCLE – MITOCHONDRIAL MATRIX PYRUVATE  2CO 2 + 1FADH + 3NADH + 1ATP *remember 2 Pyruvates from each glucose TRANSITION Pyruvate passes by active transport from the cytoplasm, through the outer and inner membranes of a mitochondria and into the mitochondrial matrix Pyruvate is DECARBOXYLATED (Carbon’s lost to form CO 2 ) – this requires O 2 hence it is AEROBIC A 2C compound forms – ACETYL CO ENZYME A NAD is reduced to form Acetyl Co A x 2 which then enters Krebs Cycle

Transition Reaction & KREBS CYCLE KREBS CYCLE Acetyl CoA joins a 4C to form 6C CITRATE Citrate is decarboxylated and dehydrogenated (releases CO2, NAD is reduced) A series of steps results back in 4C oxaloacetate - this then combines with Acetyl CoA and the process can start again Glycolysis produces 2 pyruvate molecules from a glucose molecule Each glucose molecule need s 2 cycles to be completely processed Therefore 1 glucose = 2 x 3NADH (6 NADH) 2 x FADH (2 FADH) 2 x ATP (2 ATP) The most important contribution of Krebs Cycle is the release of H + to be used in oxidative phosphorylation

OXIDATIVE PHOSPHORYLATION and the ELECTRON TRANSPORT CHAIN LOCATION: INNER MITOCHONDRIAL MEMBRANE NADH + FADH  ATP (2 x 17) electron acceptors The reduced NAD and FAD from Krebs Cycle donate the H + (electrons) to a series of hydrogen/electron carriers on the CRISTAE MEMBRANES The electrons are passed from one electron carrier to the next, losing energy as they go The hydrogen ions pass through the protein channels on the membrane - creates a CHEMIOSTATIC gradient - the H + ions returning across the membrane activate ATP SYNTHASE - 3 ATP for each NADH - 2 ATP for each FADH

OXIDATIVE PHOSPHORYLATION and the ELECTRON TRANSPORT CHAIN cont Then Oxygen is used as the FINAL ELECTRON ACCEPTOR - the H+ ions combine with the oxygen to form water 2H + + ½ O 2 + 2e -  H 2 O Oxygen is crucial and the electron transport chain cant work without it - it helps create a concentration gradient by taking away H+ 1 NADH (from Glycolysis) = 3 ATP 3 NADH (from Krebs) = 9 ATP 1 FADH (from Krebs) = 2 ATP 1 NADH (from Transition) = 3 ATP Total = 17 ATP per Pyruvate therefore 34 ATP PER GLUCOSE VIDEO: MINDBITES ELECTRON TRANSPORT CHAIN

CELLULAR RESPIRATION – Where it all occurs

ANAEROBIC RESPIRATION Cellular Respiration generally requires oxygen (for the removal of CO 2 and as the last H + acceptor during the electron transport chain) Aerobic Respiration generates A LOT OF ENERGY (36 ATP) Anaerobic Respiration is the partial breakdown of glucose to obtain energy WITHOUT OXYGEN It occurs in the cytoplasm of the cell The products of anaerobic respiration (ethanol & lactic acid) are toxic The reactions cant carry on indefinitely and do not produce a large amount of energy VIDEO: BOZEMAN ANAEROBIC RESPIRATION SUMMARY

Anaerobic Respiration The Ethanol Pathway In Yeast The Lactate Pathway In Mammals Alcoholic fermentation: SUGAR  ETHANOL + CO 2 + ENERGY Anaerobic respiration in muscle cells that produces lactic acid Lactic Acid causes burning and tiring of muscles during strenuous exercise Lactic Acid is transported to the liver via the blood  converted into pyruvate requiring oxygen  the O 2 required is called OXYGEN DEBT