Cell Respiration

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

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

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

Copyright Pearson Prentice Hall 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 Copyright Pearson Prentice Hall

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

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

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.

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*

Fermentation The first part is glycolysis.

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

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

Copyright Pearson Prentice Hall The Krebs Cycle 1 carbon is removed, forming CO2 and electrons are removed, changing NAD+ to NADH. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Krebs Cycle Coenzyme-A joins the 2-carbon molecule, forming acetyl-CoA. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Krebs Cycle Acetyl-CoA then adds the 2-carbon acetyl group to a 4- carbon compound, forming citric acid. Citric acid Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Krebs Cycle Citric acid is broken down into a 5-carbon compound, then into a 4-carbon compound. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Krebs Cycle 2 more CO2 are released and electrons join NAD+ and FAD, forming NADH and FADH2 (electron carriers) Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall The Krebs Cycle 1 molecule of ATP is generated. Copyright Pearson Prentice Hall

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

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

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

Copyright Pearson Prentice Hall Electron Transport Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Electron Transport When those electrons move down the electron transport chain, their energy is used to move H+ across the membrane Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Electron Transport H+ ions build up in the intermembrane space  becomes positively charged Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Electron Transport The other side of the membrane is now negatively charged Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Electron Transport The inner membranes of the mitochondria contain ATP synthases. ATP synthase Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Electron Transport Just like in photosynthesis, the H+ ions go thru the ATP synthase channels. Channel ATP synthase Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Electron Transport The ATP synthase is able to make ATP because of the H+ ions. Channel ATP synthase ATP Copyright Pearson Prentice Hall

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

Copyright Pearson Prentice Hall The Totals Copyright Pearson Prentice Hall

Comparing Photosynthesis and Cellular Respiration Sunlight