1. Cellular Respiration
Process whereby cells breakdown glucose and other food molecules to release energy.

2. The efficiency of cellular respiration
Provides a high % of energy in a controlled manner
Energy released from glucose banked in ATP
Energy released from glucose (as heat and light)
Gasoline energy converted to movement
100%
About 40%
25%
Burning glucose in an experiment
“Burning” glucose in cellular respiration
Burning gasoline in an auto engine
Figure 6.2B

3. BIOLOGY AND SOCIETY: FEELING THE “BURN”
When you exercise
Muscles need energy in order to perform work
Enzymes in muscle cells help a cell use glucose and oxygen to produce ATP

4. Aerobic metabolism
When enough oxygen reaches cells to support energy needs
Anaerobic metabolism
When the demand for oxygen outstrips the body’s ability to deliver it

5. Anaerobic metabolism
Without enough oxygen, muscle cells break down glucose to produce lactic acid
Lactic acid is associated with the “burn” associated with heavy exercise
If too much lactic acid builds up, your muscles give out

6. Physical conditioning allows your body to adapt to increased activity
The body can increase its ability to deliver oxygen to muscles
Long-distance runners wait until the final sprint to exceed their aerobic capacity
Figure 6.1

7. ENERGY FLOW AND CHEMICAL CYCLING IN THE BIOSPHERE
Fuel molecules in food represent solar energy
Energy stored in food can be traced back to the sun
Animals depend on plants to convert solar energy to chemical energy
This chemical energy is in the form of sugars and other organic molecules

8. Sunlight
energy
Ecosystem
Photosynthesis
(in chloroplasts)
Glucose
Carbon dioxide
Oxygen
Water
Cellular respiration
(in mitochondria)
for cellular work
Heat energy
Figure 6.3

9. Energy and Food
A large amount of energy is stored within the chemical bonds of food.
Burning 1g glucose (C6H12O6) releases 3811 C of heat.
Calorie - amount of energy needed to raise the temperature of 1g of H2O 1ºC.
Cells do not burn glucose , but gradually break it down to release the energy.

10. CELLULAR RESPIRATION: AEROBIC HARVEST OF FOOD ENERGY
The main way that chemical energy is harvested from food and converted to ATP
This is an aerobic process—it requires oxygen

11. The Relationship Between Cellular Respiration and Breathing
Cellular respiration and breathing are closely related
Cellular respiration requires a cell to exchange gases with its surroundings
Breathing exchanges these gases between the blood and outside air

12. Breathing Lungs Muscle cells Cellular respiration
Figure 6.4

13. Cellular Respiration Three Steps Glycolysis Krebs Cycle
Electron Transport Chain

14. The Overall Equation for Cellular Respiration
A common fuel molecule for cellular respiration is glucose
This is the overall equation for what happens to glucose during cellular respiration
Glucose
Oxygen
Carbon
dioxide
Water
Energy
Cellular respiration can produce up to 38 ATP molecules for each glucose molecule consumed
Unnumbered Figure 6.1

15. ATP the cell’s chemical energy
ATP molecules are the key to energy coupling
ATP molecules store energy during the process of cellular respiration
ATP power nearly all forms of cellular work

16. The Role of ATP Cellular money Cells “earn” ATP in exergonic reactions
Cells “spend” ATP in endergonic reactions
adenine P P P
ribose

17. Adenosine triphosphate Adenosine diphosphate (ADP)
Energy Coupling
Hydrolysis breaks a phosphate group bond from the ATP molecules releasing energy
The exergonic reaction supplies energy for cellular work
Adenine
Phosphate groups
Hydrolysis
Energy
Ribose
Adenosine triphosphate
Adenosine diphosphate (ADP)
Figure 5.4A

18. Potential energy of molecules
Phosphorylation
How ATP powers cellular work
Reactants
Products
Potential energy of molecules
Protein
Work
Figure 5.4B

19. Dehydration synthesis
The ATP cycle
Hydrolysis
Dehydration synthesis
Energy from exergonic reactions
Energy for endergonic reactions
Figure 5.4C

20. The Role of Oxygen in Cellular Respiration
During cellular respiration, hydrogen and its bonding electrons change partners
Hydrogen and its electrons go from sugar to oxygen, forming water

21. Why does electron transfer to oxygen release energy?
When electrons move from glucose to oxygen, it is as though they were falling
This “fall” of electrons releases energy during cellular respiration
Release
of heat
energy
Figure 6.5

22. Cell with Mitochondria (red spots)

23. Mitochondria
Site of Krebs cycle and Electron Transport Chain

24. An overview of cellular respiration
High-energy electrons carried by NADH
GLYCOLYSIS
ELECTRON TRANSPORT CHAIN AND CHEMIOSMOSIS
KREBS CYCLE
Glucose
Pyruvic acid
Cytoplasmic fluid
Mitochondrion
Figure 6.8

25. Stage 1: Glycolysis
A molecule of glucose is split into two molecules of pyruvic acid

26. Glycolysis breaks a six-carbon glucose into two three-carbon molecules
These molecules then donate high energy electrons to NAD+, forming NADH

27. Glycolysis makes some ATP directly when enzymes transfer phosphate groups from fuel molecules to ADP
Figure 6.9

28. Cell with Mitochondria (red spots)

29. Mitochondria
Site of Krebs cycle and Electron Transport Chain

30. An overview of cellular respiration
High-energy electrons carried by NADH
GLYCOLYSIS
ELECTRON TRANSPORT CHAIN AND CHEMIOSMOSIS
KREBS CYCLE
Glucose
Pyruvic acid
Cytoplasmic fluid
Mitochondrion
Figure 6.8

31. Stage 2: The Krebs Cycle
The Krebs cycle completes the breakdown of sugar

32. The Krebs cycle extracts the energy of sugar by breaking the acetic acid molecules all the way down to CO2
The cycle uses some of this energy to make ATP
The cycle also forms NADH and FADH2

33. II. Krebs Cycle Process whereby pyruvate is broken down into CO2 in a series of energy releasing reactions.
Only occurs if O2 is present (aerobic respiration).
Takes place within the mitochondria of the cell.
Each pyruvate that goes through the cycle produces 1 ATP, 4 NADH, 1 FADH2 and 3 CO2 (2 X that amount for each glucose molecule).

34. An overview of cellular respiration
High-energy electrons carried by NADH
GLYCOLYSIS
ELECTRON TRANSPORT CHAIN AND CHEMIOSMOSIS
KREBS CYCLE
Glucose
Pyruvic acid
Cytoplasmic fluid
Mitochondrion
Figure 6.8

35. Stage 3: Electron Transport
Electron transport releases the energy your cells need to make the most of their ATP

36. The molecules of electron transport chains are built into the inner membranes of mitochondria
The chain functions as a chemical machine that uses energy released by the “fall” of electrons to pump hydrogen ions across the inner mitochondrial membrane
These ions store potential energy

37. When the hydrogen ions flow back through the membrane, they release energy
The ions flow through ATP synthase
ATP synthase takes the energy from this flow and synthesizes ATP

38. The Versatility of Cellular Respiration
Cellular respiration can “burn” other kinds of molecules besides glucose
Diverse types of carbohydrates
Fats
Proteins

39. ELECTRON TRANSPORT CHAIN AND CHEMIOSMOSIS
Pathways of molecular breakdown
Food, such as peanuts
Polysaccharides
Fats
Proteins
Sugars
Glycerol
Fatty acids
Amino acids
Amino groups
Pyruvic acid
ELECTRON TRANSPORT CHAIN AND CHEMIOSMOSIS
Glucose
G3P
Acetyl CoA
KREBS CYCLE
GLYCOLYSIS
Figure 6.16

40. NADH and Electron Transport Chains
The path that electrons take on their way down from glucose to oxygen involves many stops
1/2
(from food via NADH)
Energy for
synthesis of
2 H
2 e
Electron transport chain
2 e
1/2
2 H
Figure 6.6

41. The Metabolic Pathway of Cellular Respiration
Cellular respiration is an example of a metabolic pathway
A series of chemical reactions in cells
All of the reactions involved in cellular respiration can be grouped into three main stages
Glycolysis
The Krebs cycle
Electron transport

42. FERMENTATION: ANAEROBIC HARVEST OF FOOD ENERGY
Some of your cells can actually work for short periods without oxygen
For example, muscle cells can produce ATP under anaerobic conditions
Fermentation
The anaerobic harvest of food energy

43. Fermentation in Human Muscle Cells
Human muscle cells can make ATP with and without oxygen
They have enough ATP to support activities such as quick sprinting for about 5 seconds
A secondary supply of energy (creatine phosphate) can keep muscle cells going for another 10 seconds
To keep running, your muscles must generate ATP by the anaerobic process of fermentation

44. Fermentation in Microorganisms
Various types of microorganisms perform fermentation
Yeast cells carry out a slightly different type of fermentation pathway
This pathway produces CO2 and ethyl alcohol

45. The food industry uses yeast to produce various food products
Figure 6.16

46. SUMMARY OF KEY CONCEPTS
Chemical Cycling Between Photosynthesis and Cellular Respiration
Heat
Sunlight
Cellular
respiration
Photosynthesis
Visual Summary 6.1

47. The Overall Equation for Cellular Respiration
Oxidation:
Glucose loses electrons
(and hydrogens)
Glucose
Carbon dioxide
Electrons
(and hydrogens)
Energy
Reduction:
Oxygen gains
electrons (and
hydrogens)
Oxygen
Visual Summary 6.2

48. The Metabolic Pathway of Cellular Respiration
Glucose
Oxygen
Water
Energy
Visual Summary 6.3

49. How is a Marathoner Different from a Sprinter?
Long-distance runners have many slow fibers in their muscles
Slow fibers break down glucose for ATP production aerobically (using oxygen)
These muscle cells can sustain repeated, long contractions

50. Sprinters have more fast muscle fibers
Fast fibers make ATP without oxygen - - anaerobically
They can contract quickly and supply energy for short bursts of intense activity

51. The dark meat is an example of slow fiber muscle
Leg muscles support sustained activity
The white meat consists of fast fibers
Wing muscles allow for quick bursts of flight

52. ATP needed to drive biosynthesis Cells, tissues, organisms
Biosynthesis of macromolecules from intermediates in cellular respiration
ATP needed to drive biosynthesis
GLUCOSE SYNTHESIS
KREBS CYCLE
Acetyl CoA
Pyruvic acid
G3P
Glucose
Amino groups
Amino acids
Fatty acids
Glycerol
Sugars
Proteins
Fats
Polyscaccharides
Cells, tissues, organisms
Figure 6.17