Harvesting Chemical Energy ATP--main fuel for cells Cellular Respiration--process cells use to make ATP by breaking down organic compounds

Glucose Glycolysis Krebs cycle Electron transport Fermentation (without oxygen) Alcohol or lactic acid

Glucose Glycolysis Cytoplasm Pyruvic acid Electrons carried in NADH Krebs Cycle Electrons carried in NADH and FADH 2 Electron Transport Chain Mitochondrion

The Cell Respiration Equation 6O 2 + C 6 H 12 O 6 6CO 2 + 6H 2 O + Energy oxygen + sugar carbon dioxide + water + energy

Glucose2 Pyruvic acid

Glycolysis The process of breaking 1 molecule of glucose in half Happens in the cytoplasm Produces pyruvic acid and NADH Produces 4 ATPs overall 2 ATPs used up to in the reaction Net gain = 2 ATPs

NAD+ and NADH NAD+ is a carrier molecule, it becomes NADH when it picks up energy (an electron) It is similar to NADPH, used in photosynthesis Carries high energy electrons to other places they are needed in the cell

Glycolysis This is a FAST process Thousands of ATPs can be produced in a few milliseconds However, there are a limited number of NAD+ carriers, so more must be made Without additional NAD+, glycolysis cannot continue

Glucose Glycolysis Krebs cycle Electron transport Fermentation (without oxygen) Alcohol or lactic acid

The next step of cell respiration depends on whether or not oxygen is available If no oxygen, then the next step is called FERMENTATION Fermentation is an anaerobic process Two types of fermentation--alcoholic fermentation and lactic acid fermentation

Alcoholic Fermentation Yeasts and a few other microorganisms use this pyruvic acid + NADH --> alcohol + CO 2 + NAD+ Used to produce bread, wine, beer, homeade rootbeer, etc. The “holes” in bread are from pockets of CO 2 that got trapped.

Lactic Acid Fermentation This type of fermentation happens in your muscles, and also in certain microorganisms pyruvic acid + NADH --> lactic acid + NAD+ Used to produce cheese, yogurt, soy sauce, sauerkraut, etc. Lactic acid gives these things the sharp, sour taste. YUMMMMY!

Lactic Acid Fermentation This is also the reason for runner’s fatigue or cramps When exercising strenously, your muscle cells use up all your oxygen and must switch to lactic acid fermentation Lactic acid burns when it builds up inside the cells

Lactic Acid Fermentation Since NAD+ is produced… pyruvic acid + NADH --> lactic acid + NAD+ …glycolysis can continue and more ATP can be made

Krebs Cycle Electron Transport Chain Carbon Dioxide (CO 2 ) + Water (H 2 O) Glucose (C 6 H ) + Oxygen (0 2 ) Glycolysis

After Glycolysis... Most of the energy in glucose is still not released even after glycolysis Oxygen is needed to release the remaining energy from the glucose molecule The next step is called the Krebs Cycle (if oxygen is available)

Mitochondrion

Krebs Cycle What goes IN? pyruvic acid from glycolysis Where? Mitochondrial matrix (space inside the inner membrane of mitochondria) What comes OUT? NADH and FADH 2 (both are carrier molecules for high energy electrons). These go to the next step of cellular respiration...

When pyruvic acid enters mitochondria, it reacts with coenzyme A to make acetyl CoA & releases CO 2 Krebs Cycle christae

Krebs Cycle 5 Major Steps –1) combines with oxalocetic acid to form citric acid –2) releases CO2 and NAD+ to NADH –3) CO2 released and NAD to NADH, also ATP synthesized –4) FAD (carrier molecule) to FADH2 –5) NAD+ to NADH, more oxalocetic acid created

Mitochondrion 5 Major Steps 1) combines with oxalocetic acid to form citric acid 2) releases CO2 and NAD+ to NADH 3) CO2 released and NAD to NADH, also ATP synthesized 4) FAD (carrier molecule) to FADH2 5) NAD+ to NADH, more oxalocetic acid created

Electron Transport Hydrogen Ion Movement ATP Production ATP synthase Channel Inner Membrane Matrix Intermembrane Space Mitochondrion

Electron Transport Chain What goes IN? NADH and FADH 2 from Krebs Cycle Where? Inner membrane of mitochondria What comes OUT? Lots and lots of ATP molecules!!!! (34 to be exact)

Electron Transport Hydrogen Ion Movement ATP Production ATP synthase Channel Inner Membrane Matrix Intermembrane Space Mitochondrion

Electron Transport Chain High energy electrons are passed from NADH and FADH 2 along a series of molecules As they go from molecule to molecule, they lose their energy. It is used to pump H+ into the space between inner and outer mitochondrial membrane.

Electron Transport Chain Chemiosmosis takes place, H+ ions diffuse from high to low through ATP synthase As the ATP synthase spins, this generates ATP molecules Sound familiar?

Electron Transport Chain Oxygen is the final electron acceptor in this reaction This gets rid of low energy electrons and extra H+ ions Byproduct that results is H 2 O

The Totals (Net Gains) Glycolysis + Fermentation = 2 ATP Glycolysis + Krebs + ETC = 36 ATP Even 36 ATP is only about 66% of the energy available in one glucose molecule. Where does the rest of the energy go???

The remaining 34% is given off as body heat (keeps you warm in this chilly room!)

Pacing Yourself Fermentation--used during strenuous exercise (fast breakdown of sugar) Krebs Cycle and ETC- -used during longer, paced exercises (like long-distance running) Slower, but more energy released

Why do runners breathe heavily after a race?

They are “repaying” the oxygen debt they have built up!

Photosynthesis--removes CO 2 from the atmosphere, puts back O 2 Cellular Respiration--removes O 2 from the atmosphere, puts back CO 2 6O 2 + C 6 H 12 O 6  6CO 2 + 6H 2 O + Energy 6H 2 O + 6CO 2 + light energy  C 6 H 12 O 6 + 6O 2