Cellular Respiration & Fermentation

1. Cellular Respiration & Fermentation

2. How much energy is in food? • When 1 gram of glucose (C6H12O6) is burned in the presence of oxygen, 3811 calories are released! What is a calorie? • The amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius

3. Chemical Energy & Food • On a food label, Calories (with a capital “C”) represent kilocalories! • 1 kilocalorie = 1000 calories!

4. How many calories are in 2 crackers? • 60 • 6,000 • 60,000 • Not enough info. 60,000!

5. Cellular Respiration • The slow release of energy from glucose We think of “respiration” as breathing! We take in oxygen & exhale carbon dioxide…

6. Cellular Respiration • Gas exchange occurs at the cellular level to drive cellular respiration! • O2 is a reactant. • CO2 is a waste product. • Breathing is our body’s way of getting these gases into and out of our body to perform cellular respiration!

7. Cellular Respiration & Fermentation • Methods by which organisms break down food molecules to release energy for life functions

8. Cellular Respiration & Fermentation • Both processes begin with glycolysis, breaking down glucose into 2 smaller molecules of pyruvate. • From here, whether oxygen is present or not determines the process that happens next!

9. Cellular Respiration & Fermentation • All organisms must perform some sort of respiration or fermentation in order to obtain energy from storage molecules (food)!

10. Cellular Respiration • The process that releases energy by breaking down glucose & other food molecules in the presence of oxygen O2 + C6H12O6 CO2 + H2O + ATP Oxygen + Glucose  Carbon Dioxide + Water + Energy

11. What is the balanced chemical equation for cellular respiration? • 6O2 + C6H12O66CO2 + 6H2O + 36 ATP • 4O2 + C6H12O64CO2 + 4H2O + 16 ATP • 2O2 + C6H12O62CO2 + 2H2O + 4 ATP • All ready balanced! 6O2 + C6H12O66CO2 + 6H2O + 36 ATP

12. Mitochondria – ENERGY! • Inner membrane is highly folded to increase surface area!

13. Glycolysis • The process by which 1 molecule of glucose is broken in half to produce 2 molecules (3-carbon) of pyruvate (pyruvic acid) • Occurs in the cytoplasm!

14. Glycolysis • 10 enzymatic reactions occur during glycolysis! • The 1st half of glycolysis requires 2 ATPs and the 2nd half forms 4 ATPs and 2 NADHs. • Net! There are 2 ATPs and 2 NADHs formed!

15. Fermentation – Option 1 after Glycolysis! • Occurs when no oxygen is present! • Also called “anaerobic respiration” (means without oxygen) • Turns NADH back into NAD+ so that it can be recycled & glycolysis can continue • Two types: • Alcoholic Fermentation • Lactic Acid Fermentation

16. Alcoholic Fermentation • Yeast & other microorganisms perform this Pyruvic Acid + NADH  Alcohol + CO2 + NAD+

17. Alcoholic Fermentation • Used to help us make things like bread & wine!

18. Lactic Acid Fermentation • In a shortage of oxygen in your muscle cells, it regenerates NAD+, so glycolysis can continue. • Lactic Acid builds up in your muscles, which causes pain & soreness! Pyruvic Acid + NADH  Lactic Acid + NAD+

19. Lactic Acid Fermentation • Also used by bacteria, which are used to produce yogurt & other foods (like sourdough breads, sauerkraut, pickles, & olives)!

20. Aerobic Cellular Respiration – Option 2 after Glycolysis! • The remaining 90% of the energy from the glucose molecule that was not used in glycolysis is used in the part of cellular respiration that requires oxygen (aerobic). Glycolysis

21. Cellular Respiration • Occurs when oxygen is present (aerobic respiration) • Occurs in the mitochondria! • Two parts: • Krebs Cycle • Electron Transport Chain

22. The Krebs Cycle (Citric Acid Cycle) • Pyruvate is broken down into carbon dioxide molecules in a series of steps that also form ATP, NADH, and FADH2 for use in the Electron Transport Chain! • Occurs in the matrix of the mitochondria!

23. The Electron Transport Chain • Uses high energy electrons from NADH and FADH2 from Krebs Cycle to build up H+ ions in the intermembrane space • This makes the intermembrane space positive & the matrix negative!

24. The Electron Transport Chain • The H+ ions will then move through the ATP Synthase to the negative side causing the ATP Synthase to turn. • Each turn brings ADP and a phosphate together to form high energy ATP.

25. The Krebs Cycle & ETC occur in the mitochondria!

28. Totals • Cellular Respiration produces 36 ATP molecules! • More ATP is produced with oxygen than without. • Cellular Respiration is more efficient using oxygen!

29. Energy & Exercise • Running a short race, you use ATP in your muscles & produce new ATP by lactic acid fermentation & cellular respiration!

30. Energy & Exercise • When sprinting, you produce most of your ATP using lactic acid fermentation, because you have run out of oxygen for the Krebs Cycle! You breathe heavily after a race to rebuild your ATP supply!

31. Energy & Exercise • When running a long race, you use carbohydrate energy (stored as glycogen) from your muscles & other tissues. • This will give you enough energy for up to 20 minutes of activity! • After using up the glycogen, your body will use fats for energy! • This is why aerobic exercises (like running & swimming) are beneficial for weight control!

32. Photosynthesis vs. Cellular Respiration • If storing energy is compared to money in a savings account, photosynthesis deposits the energy & cellular respiration withdraws the money! Have you noticed that Cellular Respiration is the reverse reaction of Photosynthesis?!

33. 6CO2 + 6H2O + Light  6O2 + C6H12O6 • Photosynthesis • Cellular Respiration Photosynthesis!

34. Photosynthesis vs. Cellular Respiration • PS uses CO2 in the atmosphere, but CR puts it back! • PS releases O2 into the atmosphere, but CR uses O2 to release energy from food! • CR occurs in all eukaryotes & some prokaryotes! • PS occurs only in plants, algae, & some bacteria. Other organisms (heterotrophs) get their energy by consuming other organisms!