cellular respiration
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Cellular Respiration. I. Laws of Thermodynamics. A. Energy can never be created or destroyed . The sum of energy in the universe is constant. 1. 1 st law of thermodynamics – cells cannot take energy out of thin air it must harvest it somewhere - PowerPoint PPT PresentationTRANSCRIPT
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Cellular Respiration
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I. Laws of Thermodynamics
• A. Energy can never be created or destroyed. The sum of energy in the universe is constant.– 1. 1st law of thermodynamics – cells cannot take energy
out of thin air it must harvest it somewhere– 2. 2nd law of thermodynamics – energy transfer leads to
less organization or increase in entropy
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II. Chemical Energy & Food
• A. One gram of sugar can release 3811 calories of heat (1 kilocalorie found on food labels is 1000 calories)
• B. Cells do not “burn” glucose, instead, they gradually release energy by breaking down the molecular bonds
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III. Cellular Respiration• A. Cellular Respiration is the process that releases
energy by breaking down glucose and other food molecules in the presence of oxygen.
6O2 + C6H12O6 6CO2 + 6H2O + EnergyOxygen + Glucose Carbon dioxide + Water + Energy
• B. Cellular Respiration does not release the energy at once instead it occurs in steps releasing energy little by little
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III. Cellular Respiration• C. Steps of Cellular Respiration:– 1. Glycolysis (substrate phosphorylation)• Formation of acetyl CoA
– 2. Krebs Cycle – 3. Oxidative phosphorylation/Electron Transport
Chain (ETC)• D. Each step captures some of the chemical
energy available in food molecules and uses it to produce ATP.
What is ATP?????
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IV. ATP
• A. Adenosine triphosphate (ATP) – is a molecule of adenosine bonded to three phosphates. – 1. An enormous amount of
energy is packed in between the phosphate bonds, specifically the 3rd one.
ATP ADP + Pi + energy
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Steps of Cellular Respiration
– 1. Glycolysis (substrate phosphorylation)• Formation of acetyl CoA
– 2. Krebs Cycle – 3. Oxidative phosphorylation/Electron Transport
Chain (ETC)
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V. Glycolysis• A. Glycolysis is the process in which
one molecule of glucose is broken in half, producing 2 molecules of pyruvic acid, a 3-carbon compound.
• B. Glycolysis releases energy(4) but needs a little bit of energy(2) to begin the process.
• C. During glycolysis 4 high-energy electrons are removed and carried by NAD+ converting it into 4 NADH
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Formula for glycolysis (glucose breaking)Occurs in the cytoplasmGlucose + 2ATP+2NAD+2Pyruvic acid+4ATP+ 2NADH
Several smallEnzyme rxn.s
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VI. Glycolysis Without Oxygen
• A. If oxygen is not present during glycolysis it follows a slightly different path known as fermentation.
• B. Because fermentation does not require oxygen it is said to be anaerobic. There are 2 types of fermentation– 1. Alcoholic fermentation– 2. Acid fermentation
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VI. Glycolysis Without Oxygen• a. Yeast and other microorganisms use alcoholic
fermentation, transforming pyruvic acid into ethyl alcohol and carbon dioxide waste
• b. Lactic acid is produced during rapid exercise when your muscles aren’t supplied with plenty of oxygen. (muscle cramps)
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VII. Where are we in the cell?
• Structure of a mitochondria
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IIX. Formation of Acetyl CoA
• A. When oxygen is present pyruvic acid is transported to the mitochondion.
• B. Each pyruvic acid (3-carbon molecule) is converted into acetyl coenzyme A (2-carbon molecule) and CO2 is released.
Equation: 2 Pyruvic acid + 2 Coenzyme A + 2 NAD+
2 Acetyl CoA + 2 CO2 + 2 NADH
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IX. Krebs Cycle (Citric acid)• A. In order for the Krebs cycle to follow glycolysis
you need oxygen to be present this process is said to be aerobic. (cellular respiration)
• B. During Krebs cycle acetyl coenzymes are broken down into carbon dioxide in a series of energy-extracting reactions in the mitochondria matrix. – 1. During the Krebs cycle oxaloacetate combines with
acetyl CoA to create citric acid (6-carbon molecule)– 2. The electron carriers accepting the e- (NAD+ &
FAD)will generate huge amounts of ATP
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2 pyruvic acid + 8NAD+ + 2FAD + 2ADP 6CO2 + 8NADH + 2FADH2 + 2ATP
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X. Electron Transport “Pay off”
• A. ETC uses the high-energy electrons to convert ADP to ATP– 1. e- come from NADH and FADH2
• B. The electron transport chain is located along the mitochondria inner membrane (cristae)
• C. Oxygen is the final accepter of these high-energy electrons, creating water (waste product) at the end of the reactions. This is called oxidative phosphorylation
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• All together we created 12 high energy carries2 NADH glycolysis, 2NADH Acetyl CoA, 6 NADH
Krebs, 2 FADH2 Krebs
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X. Electron Transport “Pay off”
• D. NADH & FADH2 shuttle electrons to the ETC and the hydrogen atoms are split.
H2 2H+ + 2e-• E. The e- are passed down protein carries
(cytochromes); while the hydrogen ions are pumped using some the energy across the inner membrane into the intermembrane space creating a pH gradient/proton gradient. – H ions only diffuse back through ATP synthase
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XI. The Totals
• Glycolysis: ____
• Krebs Cycle: ___
• ETC:____For every 1 NADH 3 ATP madeFor every 1 FADH2 2 ATP made
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Photosynthesis vs. Cellular Respiration
FunctionLocation (organelle)ReactantsProductsEquation