1. Ch. 9 Cellular Respiration & Fermentation

2. 9.1, Cellular Respiration Overview
chemical energy & food
food provides living things w/ chemical building blocks to grow & reproduce
organisms get energy they need from food
molecules have chemical energy that is released when chemical bonds are broken
calorie: amount of energy needed to raise temperature of 1 gram of H2O by 1°C
1 Calorie on food labels(kilocalorie)= 1000 calories

3. 9.1, Cellular Respiration cellular respiration: can occur two ways
1. Process that releases energy from food in presence of O2, called aerobic (with oxygen). 2. When no oxygen is present its called anaerobic (without oxygen).

4. Cellular Respiration: Harvesting energy stored in food
Cellular respiration: the breaking down of food to produce ATP.
Occurs in the MITOCHONDRIA
Uses oxygen (O2)
usually digesting glucose
for the energy source.
Movement of hydrogen atoms from glucose to water
Cellular Respiration Equation
glucose + oxygen  carbon + water + energy
dioxide
C6H12O6
6O2
6CO2
6H2O
ATP  +
+ heat

5. 9.1, Cellular Respiration Stages of Cellular Respiration
Glycolysis: produces little energy; ~90% stays locked in pyruvic acid after glycolysis
Krebs Cycle: little additional energy generated
Electron Transport Chain: produces most energy in cellular respiration, using O2 as electron acceptor
Fig. 9-2, pg. 252

6. 9.1 Cellular Respiration
Glycolysis: glucose, is broken down into two molecules called pyruvate. This change is accompanied by the production of 2 ATP molecules (ENERGY) and 2 NADH molecules (ENERGY TRANSPORTER). Those are the products.

7. 9.1 Cellular Respiration
Krebs Cycle: pyruvate is transported into the mitochondria and loses carbon dioxide to form acetyl-CoA. When acetyl-CoA is changed to carbon dioxide in the Krebs cycle, chemical energy is released and captured in the form of NADH, FADH2, and ATP (energy products).

8. 9.1 Cellular Respiration
Electron Transport Chain: The electron transport chain allows the release of the large amount of chemical energy stored in break down of NADH and FADH2 (gives up electron). The energy released is captured in the form ATP from ADP. 34 ATP made here. Respiration makes 36 ATP total.

9. 9.1 Cellular Respiration Where does it happen?
Glycolysis: outside the mitochondria
Krebs Cycle: inside membrane of mitochondria
Electron Transport Chain: inside membrane of mitochondria

10. Comparing Photosynthesis & Cellular Respiration
9.1, Cell Respiration
Comparing Photosynthesis & Cellular Respiration
photosynthesis removes CO2 from atmosphere, & cellular respiration puts it back.
photosynthesis releases O2 into atmosphere, & cellular respiration uses O2 to release energy from food
reactants of cellular respiration are products of photosynthesis & vice versa
Fig. 9-3, pg. 253

11. 9.2, process of cellular respiration
glycolysis
in glycolysis, 1 molecule of glucose (6-C compound) turns into molecules of pyruvic acid (3-C compound)
pyruvic acid is reactant in Krebs cycle
ATP production
2 ATP needed to start
4 ATP made (gain = 2)
Fig. 9-4, pg. 255

12. 9.2, process, cont glycolysis, cont NADH production
electron carrier NAD+ (nicotinamide adenine dinucleotide) accepts pair of high-energy electrons to become NADH
NADH carries high-energy electrons to electron transport chain
2 NADH made for every molecule of glucose in glycolysis
glycolysis works fast & w/o O2 for quick energy release

13. 9.2, process, cont Krebs cycle
in Krebs cycle, pyruvic acid broken down into CO2 by series of energy-extracting reactions
a.k.a. citric acid cycle (citric acid is 1st compound formed in series)
citric acid production
pyruvic acid from glycolysis enters matrix (innermost part of mitochondrion)

14. 9.2, process, cont Krebs, cont citric acid production, cont
w/ pyruvic acid in matrix, NAD+ accepts 2 high-energy electrons to form NADH & 1 molecule of CO2
remaining 2 C atoms react to form acetyl-CoA
acetyl-CoA combines w/ 4-C molecule to make citric acid

15. 9.2, process, cont Krebs, cont energy extraction
citric acid broken into 5-C compound, then 4-C compound; 2 CO2 released & 4-C compound can re-start cycle by combining w/ acetyl-CoA
energy released by rearranging of C bonds captured as ATP, NADH, & FADH2
each turn of cycle converts 1 ADP into ATP

16. 9.2, process, cont Krebs, cont energy extraction, cont
electron carriers NAD+ & FAD accept pairs of high-energy electrons to form NADH and FADH2 for electron transport chain to generate ATP
since glycolysis made 2 pyruvic acid, each glucose = 2 turns of cycle
each glucose molecule makes 6 CO2, 2 ATP, 8 NADH, & 2 FADH2 in cycle

17. 9.2, process, cont electron transport chain & ATP synthesis
electron transport chain uses high-energy electrons from glycolysis & Krebs cycle to turn ADP into ATP
NADH & FADH2 pass high-energy electrons to electron carrier proteins in electron transport chain
energy from chain used to move H+ ions against concentration gradient across inner mitochondrial membrane into intermembrane space

18. 9.2, process, cont chain & ATP, cont
H+ ions go back across membrane through ATP synthase, so ATP synthase molecule spins
w/ each rotation, ATP synthase attaches phosphate to ADP, making ATP
Fig. 9-6, pg. 259

19. 9.2, process, cont chain & ATP, cont
@ end of chain, electrons combine w/ H+ ions & O2 to form H2O
totals
glycolysis, Krebs cycle, & electron transport chain release ~ 36 ATP per glucose molecule
represents ~ 36 % of total energy of glucose; remaining 64 % released as heat

20. 9.3, fermentation general fermentation
w/o O2, fermentation releases energy from food molecules by producing ATP
occurs in cytoplasm
follows glycolysis; cells convert NADH from glycolysis back into NAD+, for glycolysis to continue producing ATP
Fig. 9-8, pg. 263

21. 9.3, fermentation, cont alcoholic fermentation
in yeast & some other microorganisms, produces ethyl alcohol & CO2
used to make alcoholic beverages & raise bread dough
word equation: pyruvic acid + NADH  alcohol + CO2 + NAD+
lactic acid fermentation
in most organisms, converts pyruvic acid to lactic acid
word equation: pyruvic acid + NADH  lactic acid + NAD+

22. 9.3, fermentation, cont energy & exercise
for short, quick bursts of energy, body uses ATP already in muscles & ATP made by lactic acid fermentation
extra O2 needed afterward to get rid of lactic acid produced
for exercise > 90 seconds, cellular respiration is only way to keep making ATP
releases energy more slowly than fermentation
cells in muscles have extra mitochondria for more cellular respiration

23. 9.3, fermentation, cont energy & exercise, cont
exercise > 90 seconds, cont
body stores energy in form of glycogen
glycogen stores are enough for minutes of activity
after that, body begins to break down other stored molecules (fats, etc.) for energy
hibernating animals rely on stored fat for energy