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1. Harvesting Chemical Energy • Plants and animals both use products of photosynthesis (glucose) for metabolic fuel • Heterotrophs: must take in energy from outside sources, cannot make their own e.g. animals • When we take in glucose (or other carbs), proteins, and fats-these foods don’t come to us the way our cells can use them
2. Cellular Respiration • Cellular Respiration is the process that releases energy by breaking down food molecules in the presence of oxygen. • These reactions proceed the same way in plants and animals. • 6O2 + C6H12O6 6CO2 + 6H2O + ATP Energy • Oxygen + Glucose Carbon Dioxide + Water + Energy
3. Cellular Respiration Overview • Breakdown of glucose begins in the cytoplasm: the liquid matrix inside the cell • At this point life diverges into two forms and two pathways • Anaerobic cellular respiration (aka fermentation) • Aerobic cellular respiration
Chemical Pathways Section 9-1 Glucose Electrontransport Krebs cycle Glycolysis Alcohol or lactic acid Fermentation (without oxygen)
4. Glycolysis • Series of reactions which break the 6-carbon glucose molecule down into two 3-carbon molecules called pyruvate • Process is an ancient one-all organisms from simple bacteria to humans perform it the same way • Yields 2 ATP molecules for every one glucose molecule broken down • Yields 2 NADH per glucose molecule
Glycolysis Section 9-1 Glucose 2 Pyruvic acid To the electron transport chain
5. Fermentation • Releases energy from glucose without the presence of oxygen. • There are two types of fermentation: alcoholic and lactic acid. • Alcoholic fermentation is done by yeasts and some microorganisms. It produces alcohol & Carbon Dioxide • Lactic Acid is produced by muscles during rapid exercise when the body cannot supply enough oxygen.
6. Anaerobic Cellular Respiration • Some organisms thrive in environments with little or no oxygen • Marshes, bogs, gut of animals, sewage treatment ponds • No oxygen used= ‘an’aerobic • Results in no more ATP, final steps in these pathways serve ONLY to regenerate NAD+ so it can return to pick up more electrons and hydrogen in glycolysis. • End products such as ethanol and CO2(single cell fungi (yeast) in beer/bread) or lactic acid (muscle cells)
Lactic Acid Fermentation Section 9-1 Glucose Lactic acid Pyruvic acid
7. Aerobic Cellular Respiration • Oxygen required=aerobic • 2 more sets of reactions which occur in a specialized structure within the cell called the mitochondria • Kreb’s Cycle • Electron Transport Chain
Cellular Respiration: An Overview Section 9-1 Mitochondrion Electrons carried in NADH Electrons carried in NADH and FADH2 Pyruvic acid Glucose Electron Transport Chain Krebs Cycle Glycolysis Mitochondrion Cytoplasm
8. The Krebs Cycle • During the Krebs Cycle, pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions. • Citric Acid is created in this cycle thus giving it the nickname Citric Acid cycle. • Net ATP Production is 2 ATP.
8. Kreb’s Cycle • Completes the breakdown of glucose • Takes the pyruvate (3-carbons) and breaks it down, the carbon and oxygen atoms end up in CO2 and H2O • Hydrogen and electrons are stripped and loaded onto NAD+ and FAD to produce NADH and FADH2 • Production of only 2 more ATP but loads up the coenzymes with H+ and electrons which move to the 3rd stage
9. Electron Transport Chain • The electron transport chain uses the high-energy electrons from the Krebs Cycle to convert ADP to ATP. • Total ATP 32.
9. Electron Transport Chain • Electron carriers loaded with electrons and protons from the Kreb’s cycle move to this chain-like a series of steps (staircase). • As electrons drop down stairs, energy released to form a total of 32 ATP • Oxygen waits at bottom of staircase, picks up electrons and protons and in doing so becomes water
Electron Transport Chain Section 9-2 Electron Transport Hydrogen Ion Movement Channel Mitochondrion Intermembrane Space ATP synthase Inner Membrane Matrix ATP Production
10. Energy Tally • 36 ATP for aerobic vs. 2 ATP for anaerobic • Glycolysis 2 ATP • Kreb’s 2 ATP • Electron Transport 32 ATP • 36 ATP • Anaerobic organisms can’t be too energetic but are important for global recycling of carbon
Aerobic Cellular Respiration Section 9-2 Glucose(C6H1206) + Oxygen(02) Glycolysis KrebsCycle or Citric Acid Cycle ElectronTransportChain Carbon Dioxide (CO2) + Water (H2O)
11. Energy & Exercise • Quick energy– Lactic Acid fermentation is used to get quick energy and gives off lactic acid as a by product, thus the muscle pain. • Long-Term Energy – Use cellular respiration to produce energy. Exercising or activities that last for at least 15 to 20 minutes. Best form for weight control.