Cell Respiration 2 - PDF

Cellular Respiration 1  The food we eat contain usable energy. Much of the energy is stored in a sugar form, but also as proteins, carbohydrates, and fats. That energy is transferred into ATP. Cells transfer the energ...

Cellular Respiration 1  The food we eat contain usable energy. Much of the energy is stored in a sugar form, but also as proteins, carbohydrates, and fats. That energy is transferred into ATP. Cells transfer the energy in organic compounds, especially glucose, to ATP through a process called lar Respiration 2  Cellular Respiration--is the process cells use to harvest the energy in organic compounds. The equation for cellular respiration is: 6O2 + C6H12O6 → 6CO2 + 6H2O + Energy oxygen + glucose → carbon dioxide + water + ATP ATP 3  Cellular Respiration involves three phases: 1) Glycolysis 2) Citric Acid cycle 3) Electron transport Chain 4  1) Glycolysis Glycolysis takes place in the cytoplasm. Glycolysis is the process in which one molecule of glucose is broken in half, producing two molecules of pyruvate a 3-carbon compound. 5 6 As glucose is broken down, some of its hydrogen atoms and electrons are transferred to an electron acceptor called.. NADH This forms an electron carrier called... 7 For cellular respiration to continue, the electrons carried by e NADH are donated to proteins in the Electron Transport Chain + D This turns NADH into making it available to accept more electrons. A N 8  Electrons Electrons carried carried via NADH and via NADHe FADH2 NADH Oxidative Glycolysis Citric phosphorylation: acid electron transport Glucose Pyruvate cycle and chemiosmosis Mitochondrion Cytosol ATP ATP ATP Substrate-level Substrate-level Oxidative phosphorylation phosphorylation phosphorylation 9 Glycolysis produces four ATP molecules but uses two ATP molecules yielding an net gain of two ATP 2 ATP 2 ADP 4 ADP 4 ATP It also produces 2 NADH 2NAD+ 2 2 Pyruvic acid To the electron transport chain 10 11  The end product of glycolysis is... Pyruvate What happens next to pyruvate depends on oxygen If oxygen is not available, pyruvate is further metabolized in the cytoplasm by a process called.. Fermentation Reactions without oxygen is called anaerobic 12 If oxygen is present, pyruvate enters a Mitochondrion Matrix Because oxygen is required it is said to be an aerobic pathway 13 If oxygen is present, pyruvate enters the matrix where carbon dioxide is enzymatically removed from pyruvate to form acetic acid O C O e C O e e CH e NAD+ 3 pyruvate NAD+ removes electrons to form NADH 14 acetic acid The remaining acetic acid joins an enzyme called coenzyme A Oxaloacetate Citric Acid to form coenzyme A acetyl coenzyme A acetyl-CoA C O Four carbons are added to the acetyl group CH now its called 3 Coenzyme A is removed Citric Acid C C C C Oxaloacetate Citric acid cycle Krebs Cycle Takes place in the mitochondrial matrix Citric Acid Is now within the Krebs cycle 17  The citric acid cycle turns twice for each original glucose molecule You end up with: 4---CO2 2---ATP 2---FADH2 6---NADH After the Krebs cycle, NADH and FADH now contain much of the energy that was previously stored in glucose and pyruvate. The reason for the Krebs cycle is to produce electron carriers 19 Cellular Respiration involves three phases: 1) Glycolysis Electron transport chain 2) Citric Acid cycle 3) Electron transport Chain 20  Electrons Electrons carried carried via NADH and via NADH e FADH2 NADH Oxidative Glycolysis Citric e phosphorylation: NADH acid electron transport Glucose Pyruvate cycle and chemiosmosis Mitochondrion Cytosol ATP ATP ATP Substrate-level Substrate-level Oxidative phosphorylation phosphorylation phosphorylation 21 Quiz 22  3) Electron transport Chain In prokaryotes the ETC is on the cell membrane The ETC in eukaryotes is located in the inner membrane of the mitochondrion The NADH and FADH produced by the first two steps donate their electrons to the ETC 23  Inner membrane The electrons are passed along the ETC H+ H+ H+ Outer membrane There energy is used to transport H+ ions across the membrane H+ H+ H+ H+ H+ This creates a concentration gradient of H+ 24  High concentration gradient of H+ ions Low 25 concentration gradient of H+ ions Bc. of the concentration gradient H+ want to cross the membrane They do this through the protein called ATP synthase Channel ATP synthase As H+ go through ATP synthases it causes the ATP synthases to spin. ATP Each time it rotates an ATP is produced from ADP 26  Channel At the end of the ETC, the electron ATP synthase combine with H+ ions then with O2 oxygen molecules, O 2 , form ATP water molecules The Final Electron Acceptor is Oxygen ETC 27 28 29 On average, each pair of high-energy electrons that moves down the electron transport chain provides enough energy to produce three molecules of ATP from ADP. Cellular respiration can produce 36 ATP molecules for each glucose molecule, The energy in these ATP molecules is equivalent to about 39% of the energy that was available in glucose. This conversion is more efficient than cars, who can only produce 25% of the energy from gasoline 30  What happens to the remaining 61% ? It is released as heat, which is one of the reasons our body feels warmer after exercise. 31  What is needed for pyruvate to enter the Krebs cycle? What happens if oxygen is not present following glycolysis? Pyruvate goes through the process called... Fermentation 32 Fermentation releases energy from food molecules by producing ATP in the absence of oxygen and electron transport chain Reactions without oxygen is called anaerobic During fermentation, cells convert NADH to NAD+ by passing energy electrons back to pyruvate derivatives 33 34 This action converts NADH back into NAD+, and allows glycolysis to continue producing a steady supply of ATP. 2 ATP 2 ADP 4 ADP 4 ATP Glycolysis pyruvate 2NAD+ 2 2 Pyruvic acid Fermentation 35 36 The two main types of fermentation are alcoholic fermentation. lactic acid fermentation 37  alcoholic fermentation. Glucose Glycolysis Pyruvate CO2 NAD+ NADH Ethanol 2-carbon compound Pyruvate derivatives 38 39  When yeast in dough runs out of oxygen, it begins to ferment, giving off bubbles of carbon dioxide that causes bread to rise. The small amount of alcohol produced in the dough evaporates when the bread is baked 40  lactic acid fermentation Glucose Glycolysis Pyruvate NAD+ NADH What is not produced by lactic acid fermentation? CO2 Lactic acid 41  Muscles produce lactic acid during exercise Cells contain a small amount of ATP after a few mins. of intense activity there is no ATP left. Cells begin producing ATP by lactic acid fermentation When lactic acid develops depends on a person’s fitness level. The body clears lactic acid when it develops, but it may not be able to keep up when the levels start to increase rapidly. 42 43 It is the presence of lactic acid in yogurt that gives it its sour taste, Lactic acid produced by bacteria and/or fungi in cheeses gives those cheeses their characteristic flavors 44 45 46 The End The End The End 47