1. Metabolism
All the chemical reactions in an organism

2. Catabolic pathways Break down complex molecules into simpler molecules
Releases energy
Examples?
Digestive enzymes break down food to release energy

3. Anabolic pathway Build complex molecules from simple molecules
Consume energy
Example: Body links amino acids to form muscle in response to exercise

4. Free energy

5. Free energy G
The available energy able to perform work when the temperature of a system is uniform
Chemical reaction. In a cell, a sugar molecule is broken down into simpler molecules. .
Diffusion. Molecules in a drop of dye diffuse until they are randomly dispersed.
Gravitational motion. Objects
move spontaneously from a
higher altitude to a lower one.
More free energy (higher G)
Less stable
Greater work capacity
Less free energy (lower G)
More stable
Less work capacity
In a spontaneously change
The free energy of the system decreases (∆G<0)
The system becomes more stable
The released free energy can
be harnessed to do work
(a)
(b)
(c)
Figure 8.5 

6. Exergonic reaction Energy is released
Reactions are spontaneous (not necessarily quick) and release free energy into the system
Figure 8.6
Reactants
Products
Energy
Progress of the reaction
Amount of
energy
released (∆G <0)
Free energy
(a) Exergonic reaction: energy released

7. Endergonic reaction Requires energy to proceed. Absorb free energy
Figure 8.6
Energy
Products
Amount of
energy
released (∆G>0)
Reactants
Progress of the reaction
Free energy
(b) Endergonic reaction: energy required

8. Equilibrium and Metabolism
Reactions in a closed system
Eventually reach equilibrium
Figure 8.7 A
(a) A closed hydroelectric system. Water flowing downhill turns a turbine that drives a generator providing electricity to a light bulb, but only until the system reaches equilibrium.
∆G < 0
∆G = 0

9. Cells in our body constant flow of materials in and out
metabolic pathways cannot reach equilibrium
Figure 8.7
(b) An open hydroelectric system. Flowing water keeps driving the generator because intake and outflow of water keep the system from reaching equlibrium.
∆G < 0

10. ATP - Adenine Phosphate groups Ribose Figure 8.8 NH2 HC CH C N O CH2 HOH N C HC
NH2
Adenine
Ribose
Phosphate groups - CH

11. Energy coupling Use of exergonic process to drive an endergonic one
Means that once ATP is made, the ATP can be used to fuel a process.

12. ATP Primary source of energy for coupling
Made up of adenine bound to ribose and three phosphate groups
When ATP is hydrolyzed energy is released in an endergonic reation

13. Energy is released from ATP When the terminal phosphate bond is broken
Figure 8.9 P
Adenosine triphosphate (ATP)
H2O +
Energy
Inorganic phosphate
Adenosine diphosphate (ADP)
P i
ATP drives endergonic reactions
By phosphorylation, transferring a phosphate to other molecules

14. ADP When ATP is hydrolyzed it become ADP
How many phophates does ADP have?
ATP synthesis from
ADP + P i requires energy
ATP
ADP + P i
Energy for cellular work
(endergonic, energy-
consuming processes)
Energy from catabolism
(exergonic, energy yielding
processes)
ATP hydrolysis to
ADP + P i yields energy
Figure 8.12

15. Cellular respiration

16. Mitochondria Evidence suggests they were once free living prokaryotes
Endosymbiotic theory

17. Evidence Bilayer membrane
Circular DNA separate from that of nuclear DNA
Contain ribosomes similar to those of bacteria
Formation of new mitochondria is similar to binary fission
Mitochondria and prokaryotes are similar size

18. Catabolic pathways
Energy stored in chemical bonds is released when the bond is broken
Released energy is used for work – the leftover is released as heat
Called catabolism

19. 2 types of Catabolism
Fermentation – partial breakdown of sugars that occurs without oxygen

20. 2 types of catabolism
Cellular respiration – most efficient catabolic pathway
Oxygen is consumed as a reactant, along with organic fuels such as carbohydrates, fats, and proteins to release energy
Glucose is primary nutrient used in cellular respiration

21. Cellular respiration reaction
C6H12O6 + 6O2 → 6 CO2 + 6 H2O + ATP Exergonic reaction (energy released is in the form of heat and ATP) ATP used to power all cellular activity

22. Phosphorylation
When something gains a phosphate it is called phosphorylation.
When a molecule loses a phosphate what the process called?
Dephosphorylation

23. Stages of cellular respiration
Glycolysis
Citric acid cycle
Oxidative phosphorylation: electron transport and chemiosmosis

24. Electrons carried via NADH ATP Substrate-level phosphorylation
Fig
Electrons
carried
via NADH
Glycolysis
Glucose
Pyruvate
Cytosol
Figure 9.6 An overview of cellular respiration
ATP
Substrate-level
phosphorylation

25. Electrons carried via NADH Electrons carried via NADH and FADH2
Fig
Electrons
carried
via NADH
Electrons carried
via NADH and
FADH2
Glycolysis
Citric
acid
cycle
Glucose
Pyruvate
Mitochondrion
Cytosol
Figure 9.6 An overview of cellular respiration
ATP
ATP
Substrate-level
phosphorylation
Substrate-level
phosphorylation

26. Electrons carried via NADH Electrons carried via NADH and FADH2
Fig
Electrons
carried
via NADH
Electrons carried
via NADH and
FADH2
Oxidative
phosphorylation:
electron transport
and
chemiosmosis
Glycolysis
Citric
acid
cycle
Glucose
Pyruvate
Mitochondrion
Cytosol
Figure 9.6 An overview of cellular respiration
ATP
ATP
ATP
Substrate-level
phosphorylation
Substrate-level
phosphorylation
Oxidative
phosphorylation

27. Substrate level phosphorylation
ATP produced in glycolysis and krebs cycle by substrate level phosphorylation
ATP made when enzyme transfers a phosphate group from a substrate molecule to ADP

28. Enzyme Enzyme ADP P Substrate + ATP Product Fig. 9-7
Figure 9.7 Substrate-level phosphorylation
Product

29. Energy molecules in Cell Resp
NAD+ (nicotiniacin) – coenzyme electron acceptor that acts as an oxidizing agent during cellular respiration
NADH – when NAD+ receives 2 electrons, and a proton. Used to store energy
*Similar molecules FAD, and FADH2

30. Glycolysis Location: cytosol (cytoplasm) Process
1. 6 -carbon glucose is split into carbon sugars
2. 3-carbon sugars are oxidized to form pyruvate

31. Net result Energy investment phase: Energy payoff phase:
2 ATP used to split glucose
Energy payoff phase:
2 NAD+ is used, and reduced to 2 NADH
Energy released from formation of NADH is used to produce 4 ATP
BOTTOM LINE: How many ATP are produced?
2 ATP

32. Is glycolysis aerobic? NO!!! What was the point of making the NADH?
Does not require oxygen
What was the point of making the NADH?
Remember it is an energy storing molecule!
If oxygen is present, chemical energy stored in pyruvate and NADH can be used in the next phase of cellular respiratoin

33. Conversion of pyruvate
1. Pyruvate enters the mitochondrial matrix (active transport) 2. Enzymes catalyze the conversion of pyruvate into Acetyl coenzyme A or Acetyl CoA

34. CYTOSOL MITOCHONDRION NAD+ NADH + H+ 2 1 3 Acetyl CoA Pyruvate
Fig. 9-10
CYTOSOL
MITOCHONDRION
NAD+
NADH
+ H+ 2 1 3
Acetyl CoA
Figure 9.10 Conversion of pyruvate to acetyl CoA, the junction between glycolysis and the citric acid cycle
Pyruvate
Coenzyme A
CO2
Transport protein

35. Citric acid cycle (Krebs cycle)
Cycle with many steps, each of which is catalyzed by different enzymes.
Is this process aerobic or anaerobic?

36. Pyruvate CO2 NAD+ CoA NADH + H+ Acetyl CoA CoA CoA Citric acid cycle 2
Fig. 9-11
Pyruvate
CO2
NAD+
CoA
NADH
+ H+
Acetyl CoA
CoA
CoA
Citric
acid
cycle 2
CO2
Figure 9.11 An overview of the citric acid cycle
FADH2
3 NAD+
FAD 3
NADH
+ 3 H+
ADP + P i
ATP

37. Krebs cycle (con’t) Each turn of the cycle requires one acetyl CoA
Must make 2 turns to get the products

38. Net results of Krebs Cycle
4 CO2
2 ATP
6 NADH
2 FADH2
Carbon is released during the krebs cycle! (remember the formula)

39. Review How many total molecules of ATP have been produced so far?

40. Oxidative phosphorylation
Powered by redox reactions
NADH and FADH2 are used in the next steps to make LOTS of ATP
90% of ATP made in cellular respiration made by this method

41. Electron transport chain
Electron transport chain produces energy used to make ATP during oxidative phosphorylation

42. Figure 9.13 Free-energy change during electron transport
NADH 50 2 e–
NAD+
FADH2 2 e–
FAD
Multiprotein
complexes  40
FMN
FAD
Fe•S 
Fe•S Q

Cyt b
Fe•S 30
Cyt c1 IV
Free energy (G) relative to O2 (kcal/mol)
Cyt c
Cyt a
Cyt a3 20
Figure 9.13 Free-energy change during electron transport e– 10 2
(from NADH
or FADH2)
2 H+ + 1/2 O2
H2O

43. Electron transport chain
Consists of molecules (mostly proteins) embedded in inner mitochondrial membrane
Millions located in inner mitochondrial membrane!!

44. Electron transport chain
Proteins have molecules on top that alternately oxidize and reduce
Accepting electrons reduces
Donating electrons oxidizes
Initial electron acceptor is a flavoprotein (FMN) that accepts an electron from NADH

45. Figure 9.13 Free-energy change during electron transport
NADH 50 2 e–
NAD+
FADH2 2 e–
FAD
Multiprotein
complexes  40
FMN
FAD
Fe•S 
Fe•S Q

Cyt b
Fe•S 30
Cyt c1 IV
Free energy (G) relative to O2 (kcal/mol)
Cyt c
Cyt a
Cyt a3 20
Figure 9.13 Free-energy change during electron transport e– 10 2
(from NADH
or FADH2)
2 H+ + 1/2 O2
H2O

46. Electron transport chain
FADH2 also donates electrons at a lower energy level!!
Provides one-third less energy for ATP synthesis if electron donor is FADH2 instead of NADH

47. Electron transport chain
Electrons are passed down a series of remaining molecules until they reach oxygen
Most of the remaining molecules are called cytochromes
Cytochromes-membrane bound, electron accepting proteins in the ETC

48. Figure 9.13 Free-energy change during electron transport
NADH 50 2 e–
NAD+
FADH2 2 e–
FAD
Multiprotein
complexes  40
FMN
FAD
Fe•S 
Fe•S Q

Cyt b
Fe•S 30
Cyt c1 IV
Free energy (G) relative to O2 (kcal/mol)
Cyt c
Cyt a
Cyt a3 20
Figure 9.13 Free-energy change during electron transport e– 10 2
(from NADH
or FADH2)
2 H+ + 1/2 O2
H2O

49. Electron transport chain
FINAL ELECTRON ACCEPTOR – oxygen
Binds with 2 hydrogen ions to form water
(remember formula!!)

51. Look at the picture again. Where is high energy located?
Where is low energy located?
That means the reaction is endergonic or exergonic?
exergonic

52. Result of electron transport chain
Energy from electrons used to create a proton motive force that will be used in chemiosmosis to make ATP

53. Chemiosmosis
Embedded in the mitochondrial inner membrane are ATP synthases.
What does “ase” mean the protein is?

54. Chemiosmosis
1. Energy from ETC is used to pump H+ against concentration gradient (proton-motive force)
What type of transport is this?
2. H+ move through ATP synthases down the concentration gradient
3. Movement of H+ drives the oxidative phosphorylation of ADP to ATP

55. i INTERMEMBRANE SPACE H+ Stator Rotor Internal rod Cata- lytic knob
Fig. 9-14
INTERMEMBRANE SPACE H+
Stator
Rotor
Internal
rod
Figure 9.14 ATP synthase, a molecular mill
Cata-
lytic
knob
ADP + P
ATP i
MITOCHONDRIAL MATRIX

56. Electron transport chain 2 Chemiosmosis
Fig. 9-16 H+ H+ H+ H+
Protein complex
of electron
carriers
Cyt c V Q
 
ATP synthase 
2 H+ + 1/2O2
H2O
FADH2
FAD
NADH
NAD+
Figure 9.16 Chemiosmosis couples the electron transport chain to ATP synthesis
ADP + P
ATP i
(carrying electrons
from food) H+ 1
Electron transport chain 2
Chemiosmosis
Oxidative phosphorylation

57. ATP production Glyolysis – 2 ATP Krebs cycle – 2 ATP
Oxidative phosphorylation – 34 ATP
TOTAL ATP – 36 ATP

58. Fig. 9-17
CYTOSOL
Electron shuttles
span membrane
MITOCHONDRION
2 NADH or
2 FADH2
2 NADH
2 NADH
6 NADH
2 FADH2
Glycolysis
Oxidative
phosphorylation:
electron transport
and
chemiosmosis 2
Pyruvate 2
Acetyl
CoA
Citric
acid
cycle
Glucose
+ 2 ATP
+ 2 ATP
+ about 32 or 34 ATP
Figure 9.17 ATP yield per molecule of glucose at each stage of cellular respiration
About
36 or 38 ATP
Maximum per glucose: