1. Cell Respiration

2. Glycolysis Electrons carried in NADH Pyruvic acid Glucose Cytoplasm
in NADH and
FADH2
Pyruvic acid
Glucose
Glycolysis
Cytoplasm
Mitochondrion

3. Cellular respiration
6O2 + C6H12O6  6CO2 + 6H2O + energy
oxygen + sugar  carbon + water + energy
dioxide
releases energy by breaking down glucose & other molecules in the presence of oxygen

4. Glycolysis in the cytoplasm and
1 glucose is broken, making 2 pyruvic acids
2 ADP
4 ADP
2 ATP
4 ATP
Glucose
2 Pyruvic
acid

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Glycolysis
This process uses 2 ATP but produces 4 ATP, so there is a net of 2 ATP
2 ADP
4 ADP
2 ATP
4 ATP
Glucose
2 Pyruvic
acid
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6. This reaction also gives 4 high-energy electrons to the NAD*
Glycolysis
This reaction also gives 4 high-energy electrons to the NAD*
2 ADP
4 ADP
2 ATP
4 ATP
2NAD+
2 Pyruvic
acid 2
To the electron transport chain

7. The Advantages of Glycolysis
glycolysis is fast, cells can produce thousands of ATP molecules in a few milliseconds
glycolysis does not require oxygen

8. Fermentation
After glycolysis and when oxygen is not present… …fermentation occurs
Fermentation releases energy from food molecules by producing ATP in the absence of oxygen.  it is an anaerobic process.

9. Fermentation Two types:
Alcoholic Yeasts and a few other microorganisms use alcoholic fermentation, forming ethyl alcohol and carbon dioxide as wastes.
Pyruvic acid + NADH  alcohol + CO2 + NAD*
Lactic acid
Pyruvic acid + NADH  lactic acid + NAD*

10. Fermentation
The first part is glycolysis.

11. Fermentation
The second part shows the conversion of pyruvic acid to lactic acid.

12. Aerobic vs. Anaerobic Aerobic:
requires oxygen  electron transport chain
Anaerobic:
does not require oxygen  glycolysis and fermentation

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The Krebs Cycle
1 carbon is removed, forming CO2
and
electrons are removed, changing NAD+ to NADH.
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The Krebs Cycle
Coenzyme-A joins the 2-carbon molecule, forming acetyl-CoA.
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The Krebs Cycle
Acetyl-CoA then adds the 2-carbon acetyl group to a 4- carbon compound, forming citric acid.
Citric acid
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The Krebs Cycle
Citric acid is broken down into a 5-carbon compound, then into a 4-carbon compound.
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The Krebs Cycle
2 more CO2 are released and electrons join NAD+ and FAD, forming NADH and FADH (electron carriers)
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The Krebs Cycle
1 molecule of ATP is generated.
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19. What does the cell do with all those high-energy electrons in carriers like NADH?
With oxygen, they can be used to make lots and lots of ATP  in the electron transport chain
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP

20. NADH and FADH2 are passed from one carrier protein to the next
Electron Transport
NADH and FADH2 are passed from one carrier protein to the next

21. Electron Transport
an enzyme combines these electrons with hydrogen ions and oxygen to form water

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Electron Transport
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Electron Transport
When those electrons move down the electron transport chain, their energy is used to move H+ across the membrane
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Electron Transport
H+ ions build up in the intermembrane space  becomes positively charged
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Electron Transport
The other side of the membrane is now negatively charged
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Electron Transport
The inner membranes of the mitochondria contain ATP synthases.
ATP synthase
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Electron Transport
Just like in photosynthesis, the H+ ions go thru the ATP synthase channels.
Channel
ATP synthase
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Electron Transport
The ATP synthase is able to make ATP because of the H+ ions.
Channel
ATP synthase
ATP
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29. TOTAL: 36 ATP!!! Summary Glycolysis: 2 ATP per glucose
Krebs cycle: 1 ATP from 1 pyruvic acid (2 ATP per glucose)
Electron transport chain: approx. 3 ATP from 1 electron (approx. 12 electrons  32 ATP per glucose)
TOTAL: 36 ATP!!!
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP

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The Totals
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31. Comparing Photosynthesis and Cellular Respiration
Sunlight