1. Chapter 9: Cellular Respiration

2. Chemical Energy and Food
A calorie is the energy required to raise 1g of water 1˚C
1g of glucose releases 3811 calories
1 Calorie (capital “C”) on food labels is actually a kilocalorie (1000 calories)
1g of glucose releases Calories

6. Using Chemical Energy
Plants and animals both use glucose for metabolic fuel
Glucose is not directly usable
Must be converted into ATP first

7. Cellular Respiration Overview
Converts glucose into ATP
Occurs in both plants and animals
Cellular Respiration Reaction:
C6H12O6 + 6O2 → 6CO2 + 6H2O
Opposite of photosynthesis
- 6CO2 + 6H2O → C6H12O6 + 6O2

9. to electron transport chain
Glycolysis
Series of reactions which break a 6-carbon glucose molecule into two 3-carbon molecules called pyruvic acid (a.k.a. pyruvate)
Occurs in the cytoplasm
Glucose
2 Pyruvate
2 G3P
to electron transport chain

10. to electron transport chain
Glycolysis
Process is ancient
all organisms from simple bacteria to humans perform it the same way
Yields 2 ATP and 2 NADH per glucose molecule
Glucose
2 Pyruvate
2 G3P
to electron transport chain

11. Glycolysis
Overview:
Glucose is converted into 2 pyruvic acid molecules
A.K.A. pyruvate
Pyruvic acid is a reactant in the Krebs Cycle

12. Glycolysis
Step 1:
The cell invests 2 ATP to convert glucose  2 G3P

13. Glycolysis
Step 2:
4 ATP molecules are produced from the conversion of 2 G3P  2 pyruvic acid
2 NADH molecules are produced
Used in E.T.C.

14. Glycolysis

17. Aerobic Cellular Respiration
Oxygen required = aerobic
2 more sets of reactions which occur in a specialized organelles called mitochondria
1. The Krebs Cycle
2. The Electron Transport Chain

19. The Krebs Cycle AKA The Citric Acid Cycle
Completes the breakdown of glucose
Carbon and oxygen atoms end up in CO2 and H2O, respectively
Produces only 2 more ATP
but produces electron carriers NADH and FADH2 which move to the 3rd stage (The Electron Transport Chain)

20. The Krebs Cycle
Citric Acid Production

21. The Krebs Cycle Products (per glucose): 6 CO2 2 ATP 8 NADH 2 FADH2
to E.T.C.

25. Electron Transport Chain
Powered by electron carriers from the Kreb’s Cycle
Produces a total of 32 ATP
Water is formed when oxygen combines with protons

26. The Electron Transport Chain
Hydrogen Ion Movement
Electron Transport
H+ Active Transport
H+ Diffusion
Intermembrane
Space
ATP synthase
Inner Membrane
Mitochondrial Matrix
ATP Production

28. Energy Tally 36 ATP for aerobic vs. 2 ATP for anaerobic
Glycolysis ATP
Krebs ATP
Electron Transport Chain 32 ATP
36 ATP
Anaerobic organisms can’t be too energetic but are important for global recycling of carbon

33. Anaerobic Cellular Respiration
Also called fermentation
Some organisms thrive in environments with little or no oxygen
Marshes, bogs, digestive tracts, sewage treatment tanks, etc.
No oxygen used = anaerobic
Results in no more ATP
The final steps in these pathways serve ONLY to regenerate NAD+ so it can keep glycolysis running
End products such as ethanol and CO2 (yeast in beer/bread) or lactic acid (muscle cells)

34. Fermentation Overview

35. Alcoholic Fermentation
Used by yeasts and other microorganisms
Produces carbon dioxide and ethanol
Used to make bread and alcoholic drinks (beer, wine, etc.)

36. Lactic Acid Fermentation
Used by both unicellular and multicellular organisms
Lactic acid buildup in muscles causes a burning sensation
Used in the production of sour cream, cheese, yogurt, and many other foods & beverages
Glucose
Pyruvic Acid
Lactic Acid

37. Fermentation Overview