1. Cellular Respiration 9-1 – 9-2

2. Chemical Energy and Food
All living things consume and use energy
Heterotrophs take in food which is digested and broken down into C6H12O6
Autotrophs can’t “eat” so they make C6H12O6 through photosynthesis
Mitochondria then transform the “food energy” into chemical energy ( )
ATP

3. Chemical Energy and Food
Calories
Unit of measurement for energy
Amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius
Nutrition information on food is Calories (1000 calories)

4. Chemical Energy and Food
Calories
1 gram of glucose (sugar) produces 3811 calories when burned
A lot of energy for a cell
Our bodies use glycolysis and cellular respiration to gradually release energy in food

5. Overview of Cellular Respiration
Mitochondria “make change” energetically
Take the energy in a sugar and convert it into more conveniently-sized packages 
ATP

6. Overview of Cellular Respiration
Definition: process that releases energy by breaking down glucose and other food molecules
Requires oxygen

7. Overview of Cellular Respiration
C6H12O6 + 6O2 → 6CO H2O + energy
ATP
Carbohydrate
Oxygen
Carbon
dioxide
Water

8. Overview of Cellular Respiration
Step 1: Glycolysis
Step 2: Krebs cycle
Step 3: Electron transport chain

9. Overview of Cellular Respiration
CYTOPLASM:
Glycolysis
Outer membrane
MATRIX:
Breakdown of
pyruvic acid,
Krebs cycle
INNER MEMBRANE:
Electron transport
chain
MITOCHONDRION

10. Step 1: Glycolysis Occurs in cytoplasm of ALL cells
Does not require oxygen
Process of splitting a glucose (C6H12O6) molecule in half

11. Step 1: Glycolysis Products: 2 pyruvic acid molecules
What you get when you split glucose in half
Used in Krebs cycle
Energized electrons
Carried to the electron transport chain (ETC) by
Used to generate
NADH
ATP

12. Step 1: Glycolysis Products: 2 Net yield = 2 Uses up 2 ATP
Produces 4 ATP
Net yield = 2
ATP
ATP

13. Step 1: Glycolysis
1 Glucose
C6H12O6

14. Step 1: Glycolysis
ATP 2
2 ADP
1 Glucose
C6H12O6

15. Step 1: Glycolysis
ATP 2
2 ADP P
1 Glucose
C6H12O6 P
2 PGAL

16. Step 1: Glycolysis ATP 2 2 ADP 4ADP + 4 Pi 4ATP 1 Glucose C6H12O6
2 NAD+
2 NADH P
2 PGAL
To ETC

17. Step 1: Glycolysis ATP 2 2 ADP 4ADP + 4 Pi 4ATP 1 Glucose C6H12O6
2 Pyruvic
acid
2 NAD+
2 NADH P
2 PGAL
To ETC

18. Step 1: Glycolysis
If oxygen is present pyruvic acid molecules enter the mitochondria for the Krebs cycle
Leads to production of lots of
If oxygen is absent pyruvic acid molecules stay in the cytoplasm for fermentation
No more ATP is produced 
ATP

19. Cellular Respiration C6H12O6 + 6O2 → 6CO2 + 6H2O + energy Carbohydrate
ATP
Carbohydrate
Oxygen
Carbon
dioxide
Water

20. Cellular Respiration Step 1: Glycolysis Step 2: Krebs cycle
Step 3: Electron transport chain

21. Step 2: Krebs Cycle Requires oxygen
If there is no oxygen present pyruvic acid stays in the cytoplasm and does fermentation

22. Step 2: Krebs Cycle
Involves first breaking down pyruvic acid formed during glycolysis
Occurs as pyruvic acid crosses the mitochondrial membrane
Rest of the cycle occurs in the mitochondrial matrix

23. Step 2: Krebs Cycle Products: 3 CO2 2 Lots more energized electrons
Exhaled 2
Lots more energized electrons
Carried to ETC by and
Used to generate more
ATP
NADH
FADH2
ATP

24. Step 2: Krebs Cycle – Break Down of Pyruvic Acid
CYTOPLASM
Mitochondrial
membrane
MITOCHONDRION
To ETC
3 carbons
NADH
NAD+ TO
KREBS
CYCLE
Co-A
Pyruvic
acid
(from glycolysis)
Acetyl Co-A
Co-A
CO2
Exhaled

25. KREBS CYCLE Co-A Co-A FADH2 FAD Citric NADH Acid NAD+ CO2 4 carbon
compound
NAD+
NADH
ATP
5-carbon
compound
ADP
NADH
NAD+
CO2

26. Cellular Respiration C6H12O6 + 6O2 → 6CO2 + 6H2O + energy Carbohydrate
ATP
Carbohydrate
Oxygen
Carbon
dioxide
Water

27. Cellular Respiration Step 1: Glycolysis Step 2: Krebs cycle
Step 3: Electron transport chain

28. Cellular Respiration CYTOPLASM MITOCHONDRION Outer membrane
Inner membrane
Mitochondrial
matrix
MITOCHONDRION
Intermembrane
space

29. Step 3: Electron Transport Chain
Happens on inner membrane of mitochondria
Major production of
Uses energized electrons delivered by and created during glycolysis and the Krebs cycle
ATP
NADH
FADH2

30. Step 3: Electron Transport Chain
Energized electrons are passed along a series of molecules embedded in the inner mitochondrial membrane
ETC molecules take the electrons’ energy
Uses energy to make
ATP

31. Step 3: Electron Transport Chain
CYTOPLASM
OUTER
MEMBRANE
ELECTRON TRANSPORT CHAIN
INTER
MEMBRANE
SPACE
INNER
MEMBRANE
MITOCHONDRIAL
MATRIX

32. Step 3: Electron Transport Chain
Oxygen is the final electron acceptor
If oxygen is not present electrons stop flowing through ETC
ATP production stops
Combines with H+ ions to form water

33. Step 3: Electron Transport Chain
CYTOPLASM
OUTER
MEMBRANE
ELECTRON TRANSPORT CHAIN
INTER
MEMBRANE
SPACE
INNER
MEMBRANE
MITOCHONDRIAL
MATRIX

34. Cellular Respiration C6H12O6 + 6O2 → 6CO2 + 6H2O + energy Carbohydrate
ATP
Carbohydrate
Oxygen
Carbon
dioxide
Water

35. Overall ATP Production
FOR EVERY GLUCOSE MOLECULE:
ATP
Glycolysis produces 2
ATP
Krebs cycle produces
Electron transport chain
produces **32
ATP
**Makes ATP from electrons carried
to it from the first 3 steps

36. Overall ATP Production
cellular
respiration
makes 36

37. Fermentation
Occurs when there is no oxygen available

38. Fermentation
Pyruvic acid molecules are still formed through glycolysis
Occurs in the cytoplasm
Mitochondria are not involved
Pyruvic acid is broken down differently:
No ATP is produced after glycolysis

39. Fermentation
2 types:
Alcoholic fermentation
Lactic acid fermentation

40. Alcoholic Fermentation
Ethyl alcohol and CO2 are byproducts
Occurs in organisms that live in environments lacking oxygen

41. Alcoholic Fermentation
Glycolysis
2 CO2
2 Ethanol

42. Alcoholic Fermentation
Example: yeast
When spores are placed in a food-rich, oxygen-free environment the organisms come to life
Begin doing alcoholic fermentation
CO2 produced makes bread rise
Tiny amounts of alcohol produced evaporate as bread bakes

43. Lactic Acid Fermentation
Performed by cells when they run out of oxygen
After glycolysis pyruvic acid is transformed into lactic acid
Causes burning sensation in muscles

44. Lactic Acid Fermentation
Glycolysis
Glucose
Pyruvic acid
Lactic acid

45. Energy and Exercise
Muscle cells use tremendous amounts of ATP to contract and create movement
Cells keep a small amount of ATP on hand
Enough for only a few seconds of intense exercise
After that ATP is produced by lactic acid fermentation

46. Energy and Exercise
Lactic acid fermentation can provide ATP for about 90 seconds of intense exercise
Lactic acid is produced by a series of reactions that require extra oxygen
Reason for breathing heavily at the end of a longer race

47. Energy and Exercise
Cellular respiration is the only way to generate ATP after 90 seconds
Slow process
Why a marathon and a sprint look differently

48. Energy and Exercise
Cellular respiration is the only way to generate ATP after 90 seconds
Slow process
Why a marathon and a sprint look differently
Training allows a person to exercise more vigorously beyond the 90 second barrier

49. Energy and Exercise Fuel for making ATP is stored as glycogen
Carbohydrate
Body contains enough glycogen to fuel cellular respiration for minutes
Body burns fat after that