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Learn about the process of cellular respiration, where cells break down stored energy in food to produce ATP, the energy currency of life. Discover the different stages of cellular respiration and understand the importance of oxygen and electron carriers. Explore aerobic and anaerobic respiration, including fermentation, and see how these processes relate to the overall energy needs of living organisms.
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Cell Energy Part 2: Cellular Respiration:Section 4.4 & 4.5
What’s thepoint? The pointis to makeATP! ATP
The energy needs of life What do we need energy for? • synthesis • building biomolecules • reproduction • movement • active transport • temperature regulation
food O2 ATP What do we need to make energy? Make ATP!Make ATP!All I do all day…And no oneeven notices! • The “Furnace” • mitochondria • Fuel • food • carbohydrates, fats, proteins • The Helpers • oxygen • enzymes
Mitochondria MITOCHONDRION Outermembrane Intermembranespace Innermembrane Cristae Matrix
Overview of cellular respiration High-energy electrons carried by NADH GLYCOLYSIS ELECTRONTRANSPORT CHAIN Krebs Cycle Pyruvicacid Glucose Mitochondrion Cytoplasmicfluid
Cellular Respiration Equation: • Does this look familiar? Oxygen gas Carbon dioxide Water Energy Glucose
Cellular Respiration: • Series of reactions in which cells break down stored energy in food to make chemical energy (ATP) for performing all life functions. • Happens in the mitochondria of both plant and animal cells.
glucose pyruvate 3C 6C 2x It starts with Glycolysis In thecytoplasm?Why doesthat makeevolutionarysense? • Breaking down glucose • “glyco – lysis” (means splitting sugar) • ancient pathway which harvests energy • inefficient • generates only 2 ATP for every 1 glucose • occurs in cytoplasm of the cell
After Glycolysis? The fate of Pyruvate NO O2 Anaerobic Fermentation happens (occurs in cytoplasm) O2 present Aerobic Respirationhappens (occurs in a mitochondria) Krebs Cycle Yeast Bacteria, Animal muscles Alcohol Lactic Acid ETC
If O2 is present, Aerobic Respiration occurs • If is present in the cells, aerobic respiration will happen • Aerobic Respiration:series of reactions that happen in the presence of oxygen, in a mitochondria, and produce LOTS of ATP • Happens in 2 parts: • Krebs cycle (aka: Citric Acid Cycle) • Electron Transport Chain (ETC)
Krebs cycle • aka: Citric Acid Cycle • Occurs in mitochondrial matrix • 8 step pathway • each step catalyzed by specific enzyme • Evolved later than glycolysis • does that make evolutionary sense? • bacteria 3.5 billion years ago (glycolysis) • free O22.7 billion years ago (photosynthesis) • eukaryotes 1.5 billion years ago (aerobic respiration = organelles mitochondria) Hans Krebs 1900-1981
H+ H+ H+ H+ H+ H+ H+ H+ H+ Electron Carriers = Hydrogen Carriers • Krebs cycle produces large quantities of electron carriers • NADH • FADH2 • These go to Electron Transport Chain ADP+ Pi ATP What’s so important about electron carriers?
No Oxygen Anaerobic RespirationChapter 4.6
O2 What if oxygen is missing? • Can’t complete aerobic respiration • Anaerobic respiration / Fermentation: • Happens in the cytoplasm of the cell • The pyruvate from glycolysis is broken down to either lactic acid (animals or bacteria) or alcohol and CO2 (yeast) • This is done when organisms are low in oxygen • Ex. Hibernating animals, people doing strenuous exercise, bacteria or yeast living in low oxygen environments.
O2 2 Types of Fermentation • alcohol fermentation • Done by yeast • glucose ATP + CO2+ alcohol • make beer, wine, bread • lactic acid fermentation • Done by bacteria, animals • glucose ATP + lactic acid • make yogurt • Waste product in muscles during anaerobic exercise But both only make a little bit of ATP!
pyruvate ethanol + CO2 3C 2C 1C NADH NAD+ bacteria yeast Alcohol Fermentation • Dead end process • at ~12% ethanol, kills yeast • can’t reverse the reaction Count thecarbons!
O2 pyruvate lactic acid NADH NAD+ 3C 3C animals Lactic Acid Fermentation • Reversible process • once O2 is available, lactic acid is converted back to pyruvate by the liver Count thecarbons!
O2 O2 Pyruvate is a branching point Pyruvate fermentation anaerobicrespiration mitochondria Krebs cycle aerobic respiration
Products of Fermentation • Lactic Acid fermentation: • cheese, yogurt (bacteria), • Lactic Acid builds up in human muscles during strenuous extercise • Alcoholic fermentation: • beer, wine, & bread.
Check this out! • Cellular Respiration Video • http://www.youtube.com/watch?v=j7gPtASv0SQ