Cellular respiration consists of several interconnected metabolic pathways that occur in the mitochondria to convert the chemical energy from glucose into usable ATP. These pathways include glycolysis, the link reaction, the Krebs cycle, the electron transport chain, and chemiosmosis. In glycolysis, glucose is broken down to pyruvate in the cytoplasm, producing a small amount of ATP. In the link reaction, pyruvate is converted to acetyl-CoA, with carbon dioxide released. The Krebs cycle further oxidizes acetyl-CoA, producing carbon dioxide and reducing electron carriers NADH and FADH2. These electrons are passed through the electron transport chain in the inner mitochondrial membrane, pumping hydrogen ions across the membrane.

1. 8.2 Cellular Respiration
Essential idea: Energy is converted to a useable form in cellular
respiration
https://usatftw.files.wordpress.com/2013/09/gty-1775738061.jpg?w=1024&h=681
World's strongest man lift 975 pounds

2. Understandings
Statement Guidance
8.2 U.1 Cell respiration involves the oxidation and reduction of electron
carriers.
8.2 U.2 Phosphorylation of molecules makes them less stable.
8.2 U.3 In glycolysis, glucose is converted to pyruvate in the cytoplasm. The names of the intermediate
compounds in glycolysis is not
required.
8.2 U.4 Glycolysis gives a small net gain of ATP without the use of oxygen. The names of the intermediate
compounds in glycolysis is not
required.
8.2 U.5 In aerobic cell respiration pyruvate is decarboxylated and oxidized,
and converted into acetyl compound and attached to coenzyme A to
form acetyl coenzyme A in the link reaction.
8.2 U.6 In the Krebs cycle, the oxidation of acetyl groups is coupled to the
reduction of hydrogen carriers, liberating carbon dioxide.
The names of the intermediate
compounds in the Krebs cycle is not
required.
8.2 U.7 Energy released by oxidation reactions is carried to the cristae of
the mitochondria by reduced NAD and FAD.
8.2 U.8 Transfer of electrons between carriers in the electron transport
chain in the membrane of the cristae is coupled to proton pumping.
8.2 U.9 In chemiosmosis protons diffuse through ATP synthase to generate
ATP.
8.2 U.10 Oxygen is needed to bind with the free protons to maintain the
hydrogen gradient, resulting in the formation of water.
8.2 U.11 The structure of the mitochondrion is adapted to the function it
performs.

3. Applications and Skills
Statement Guidance
8.2 A.1 Electron tomography used to produce images of
active mitochondria.
8.2 S.1 Analysis of diagrams of the pathways of aerobic
respiration to deduce where decarboxylation
and oxidation reactions occur.
8.2 S.2 Annotation of a diagram of a mitochondrion to
indicate the adaptations to its function.

8. Respiration consists of several different
interlinked metabolic pathways.
chemiosmosis

9. Respiration consists of several different
interlinked metabolic pathways.
chemiosmosis

11. 8.2 U.11 The structure of the mitochondrion is adapted to the function it performs.
8.2 S.2 Annotation of a diagram of a mitochondrion to indicate the adaptations to its function.
Label the structures:
http://commons.wikimedia.org/wiki/File:Animal_mitochondrion_diagram_en.svg

12. Label the structures: matrix
Inter-membrane space
ribosomes inner membrane
outer membrane
naked loops of DNA
cristae
http://commons.wikimedia.org/wiki/File:Animal_mitochondrion_diagram_en.svg
8.2 U.11 The structure of the mitochondrion is adapted to the function it performs.
8.2 S.2 Annotation of a diagram of a mitochondrion to indicate the adaptations to its function.

13. 8.2 U.1 The structure of the mitochondrion is adapted to the function it performs.
8.2 S.2 Annotation of a diagram of a mitochondrion to indicate the adaptations to its function.

14. 8.2 U.11 The structure of the mitochondrion is adapted to the function it performs.
8.2 S.2 Annotation of a diagram of a mitochondrion to indicate the adaptations to its function.

15. 8.2 A.1 Electron tomography used to produce images of active
mitochondria.
Electron tomography is a technique for obtaining 3D structures of sub-cellular
structures using electron micrographs.
Electron tomography is improving the understanding
of mitochondria structure and function.
Use the link to find out
more:http://www.sci.sdsu.edu/TFrey/MitoMovie.htm

16. 8.2 U.11 The structure of the mitochondrion is adapted to the function it performs.
8.2 S.2 Annotation of a diagram of a mitochondrion to indicate the adaptations to its function.

17. 8.2 U.1 Cell respiration involves the oxidation and reduction of electron
carriers.
What is oxidation?

18. 8.2 U.1 Cell respiration involves the oxidation and reduction of electron
carriers.
What is oxidation?

19. What is oxidation?
8.2 U.1 Cell respiration involves the oxidation and reduction of electron
carriers.

20. Who are the electron carries in cell respiration?
NAD+ + 2H+ + 2e- NADH + H+
reduction
oxidation
NAD+ NADH + H+
reduction
oxidation
The most common hydrogen carrier is NAD
(Nicotinamide Adenine Dinucleotide)
Use the simplified form of the equation omitting
the detail of the H+ ions and electrons:
8.2 U.1 Cell respiration involves the oxidation and reduction of electron
carriers.

21. Who are the electron carries in cell respiration?
Another less frequently used hydrogen carrier is
FAD (Flavin Adenine Dinucleotide).
Use the simplified form of the equation omitting
the detail of the H+ ions and electrons:
FAD + 2H+ + 2e- FADH2
reduction
oxidation
FAD FADH2
oxidation
reduction
8.2 U.1 Cell respiration involves the oxidation and reduction of electron
carriers.

22. Respiration consists of several different
interlinked metabolic pathways.
glycolysis chemiosmosis

23. Glycolysis is the splitting of glucose into pyruvate
http://www.science.smith.edu/departments/Biology/Bio231/gl
ycolysis.html
http://highered.mheducation.com/sites/0072507470/student_
view0/chapter25/animation__how_glycolysis_works.html
Use the animations to learn about the
process of glycolysis
8.2 U.1 Cell respiration involves the oxidation and reduction of electron
carriers.

24. 8.2 U.3 In glycolysis, glucose is converted to pyruvate in the cytoplasm.
8.2 U.4 Glycolysis gives a small net gain of ATP without the use of oxygen.
Glycolysis is the splitting of glucose into pyruvate
by substrate-level phosphorylation.

25. 8.2 U.2 Phosphorylation of molecules makes them less stable.
Phosphorylation is a reaction where a phosphate group (PO4
3-) is added to an organic
molecule
http://commons.wikimedia.org/wiki/File:Glycolysis2.svg
The phosphorylated
molecule is less stable
and therefore reacts
more easily in the
metabolic pathway.
The phosphate group is
usually transferred from ATP
Reactions that would otherwise proceed slowly and require energy into a reaction that
happens quickly releasing energy.

26. Glycolysis is the splitting of glucose into pyruvate
8.2 U.3 In glycolysis, glucose is converted to pyruvate in the cytoplasm.
8.2 U.4 Glycolysis gives a small net gain of ATP without the use of oxygen.
In Summary:
• Glycolysis occurs in cytoplasm
• A hexose sugar (e.g. glucose) is phosphorylated using ATP
• The hexose phosphate is then split into two triose phosphates
• Oxidation occurs removing hydrogen
• The hydrogen is used to reduce NAD to NADH
• Four ATP are produced resulting in a net gain of two ATP
• Two pyruvate molecules are produced at the end of glycolysis
http://en.wikipedia.org/wiki/Glycolysis

27. Respiration consists of several different
interlinked metabolic pathways.
linkreaction chemiosmosis

28. 8.2.U.5 In aerobic cell respiration pyruvate is decarboxylated and oxidized, and converted into
acetyl compound and attached to coenzyme A to form acetyl coenzyme A in the link reaction.

29. 8.2.U.5 In aerobic cell respiration pyruvate is decarboxylated and oxidized, and converted into
acetyl compound and attached to coenzyme A to form acetyl coenzyme A in the link reaction.

30. 8.2.U.5 In aerobic cell respiration pyruvate is decarboxylated and oxidized, and converted into
acetyl compound and attached to coenzyme A to form acetyl coenzyme A in the link reaction.

31. 8.2.U.5 In aerobic cell respiration pyruvate is decarboxylated and oxidized, and converted into
acetyl compound and attached to coenzyme A to form acetyl coenzyme A in the link reaction.

32. 8.2.U.5 In aerobic cell respiration pyruvate is decarboxylated and oxidized, and converted into
acetyl compound and attached to coenzyme A to form acetyl coenzyme A in the link reaction.

33. In Summary:
• pyruvate (from glycolysis) enters the mitochondrion matrix
• enzymes remove one carbon dioxide and hydrogen from the pyruvate
• hydrogen is accepted by NAD to form NADH
• removal of hydrogen is oxidation
• removal of carbon dioxide is decarboxylation
• the link reaction is therefore oxidative decarboxylation
• the product is an acetyl group which reacts with coenzyme A
• acetyl CoA enters Krebs cycle
8.2.U.5 In aerobic cell respiration pyruvate is decarboxylated and oxidized, and converted into
acetyl compound and attached to coenzyme A to form acetyl coenzyme A in the link reaction.

34. chemiosmosisKreb’scycle

35. 8.2 U.6 In the Krebs cycle, the oxidation of acetyl groups is coupled to
the reduction of hydrogen carriers, liberating carbon
Krebs cycle reduces electron carriers in
preparation for oxidative phosphorylation
(carbon is released as CO2 as a by-product)
Use the animations to learn about Krebs
cycle
http://highered.mheducation.com/olcweb/cgi/pluginpop
.cgi?it=swf::525::530::/sites/dl/free/0072464631/291136
/krebsCycle.swf::krebsCycle.swf
http://www.wiley.com/college/pratt/0471393878/stu
dent/animations/citric_acid_cycle/index.html
http://www.wiley.com/legacy/college/boyer/047
0003790/animations/tca/tca.htm
http://faculty.nl.edu/jste/aerobic_respirat
ion.htm#Citric%20acid%20%28CA%29%2
0cycle

36. 8.2 U.6 In the Krebs cycle, the oxidation of acetyl groups is coupled to
the reduction of hydrogen carriers, liberating carbon

37. 8.2 U.6 In the Krebs cycle, the oxidation of acetyl groups is coupled to
the reduction of hydrogen carriers, liberating carbon

38. 8.2 U.6 In the Krebs cycle, the oxidation of acetyl groups is coupled to
the reduction of hydrogen carriers, liberating carbon

39. H+
8.2 U.6 In the Krebs cycle, the oxidation of acetyl groups is coupled to
the reduction of hydrogen carriers, liberating carbon

40. NADH H+
8.2 U.6 In the Krebs cycle, the oxidation of acetyl groups is coupled to
the reduction of hydrogen carriers, liberating carbon

41. 8.2 U.6 In the Krebs cycle, the oxidation of acetyl groups is coupled to
the reduction of hydrogen carriers, liberating carbon

42. 8.2 U.6 In the Krebs cycle, the oxidation of acetyl groups is coupled to
the reduction of hydrogen carriers, liberating carbon

43. 8.2 U.6 In the Krebs cycle, the oxidation of acetyl groups is coupled to
the reduction of hydrogen carriers, liberating carbon

44. 8.2 U.6 In the Krebs cycle, the oxidation of acetyl groups is coupled to
the reduction of hydrogen carriers, liberating carbon

45. 8.2 U.7 Energy released by oxidation reactions is carried to the cristae of
the mitochondria by reduced NAD and FAD.
The reduced forms of NAD and FAD
carry H+ ions and electrons to the
electron transport chain, is which is
situated in the folds on the inner
membrane, i.e. the cristae.

46. In Summary:
• acetyl CoA enters the Krebs cycle
• acetyl group (2C) joins a 4C sugar to form a 6C sugar
• oxidative decarboxylation of the 6C sugar to a 5C compound produces
CO2
• oxidative decarboxylation of the 5C compound to a 4C compound
produces CO2
• The process is oxidative as NAD and FAD are reduced by the addition of
hydrogen
• two CO2 are produced per molecule of pyruvate / cycle
• along with three NADH + H+ and one FADH2 per molecule of pyruvate /
cycle
• one ATP is produced by substrate level phosphorylation (from ADP + Pi)
per molecule of pyruvate / cycle
• NADH and FADH2 provide electrons to the electron transport chain
8.2 U.6 In the Krebs cycle, the oxidation of acetyl groups is coupled to
the reduction of hydrogen carriers, liberating carbon dioxide.

47. 8.2 S.1 Analysis of diagrams of the pathways of aerobic respiration to
deduce where decarboxylation and oxidation reactions occur.
1. Indicate two places where
decarboxylation occurs. (1)
2. Explain why the given places where
selected. (1)

48. 1. Indicate two places where
decarboxylation occurs. (1)
2. Explain why the given places where
selected. (1)
decarboxylationdecarboxylation
decarboxylation
The molecule reduces the number of
carbon atoms it contains in each
place, therefore each reaction must
be a decarboxylation.
8.2 S.1 Analysis of diagrams of the pathways of aerobic respiration to
deduce where decarboxylation and oxidation reactions occur.

49. 3. The diagram shows the three stages of glycolysis.
Which processes are indicated by I, II and III?
I II III
A Lysis Phosphorylation Oxidation and ATP
formation
B Oxidation and
ATP formation
Phosphorylation Lysis
C Phosphorylation Lysis Oxidation and ATP
formation
D Phosphorylation Oxidation and
ATP formation
Lysis
8.2 S.1 Analysis of diagrams of the pathways of aerobic respiration to
deduce where decarboxylation and oxidation reactions occur.

50. 3. The diagram shows the three stages of glycolysis.
Which processes are indicated by I, II and III?
I II III
A Lysis Phosphorylation Oxidation and ATP
formation
B Oxidation and
ATP formation
Phosphorylation Lysis
C Phosphorylation Lysis Oxidation and ATP
formation
D Phosphorylation Oxidation and
ATP formation
Lysis
8.2 S.1 Analysis of diagrams of the pathways of aerobic respiration to
deduce where decarboxylation and oxidation reactions occur.

51. chemiosmosis
electron
transport
chain

52. 8.2 U.8 Transfer of electrons between carriers in the electron transport
chain in the membrane of the cristae is coupled to proton pumping.
Oxidative phosphorylation part I:
electron transport chain (ETC)
The process of oxidative
phosphorylation happens
across the inner membrane
A series of integral protein
complexes act as electron carriers
forming the electron transport chain

53. Oxidative phosphorylation part I:
electron transport chain (ETC)
8.2 U.8 Transfer of electrons between carriers in the electron transport
chain in the membrane of the cristae is coupled to proton pumping.

54. Oxidative phosphorylation part I:
electron transport chain (ETC)
8.2 U.8 Transfer of electrons between carriers in the electron transport
chain in the membrane of the cristae is coupled to proton pumping.

55. Oxidative phosphorylation part I:
electron transport chain (ETC)
8.2 U.8 Transfer of electrons between carriers in the electron transport
chain in the membrane of the cristae is coupled to proton pumping.

56. Oxidative phosphorylation part I:
electron transport chain (ETC)
8.2 U.8 Transfer of electrons between carriers in the electron transport
chain in the membrane of the cristae is coupled to proton pumping.

57. chemiosmosis

58. 8.2 U.9 In chemiosmosis protons diffuse through ATP synthase to
generate ATP.

59. 8.2 U.9 In chemiosmosis protons diffuse through ATP synthase to
generate ATP.

60. 8.2 U.9 In chemiosmosis protons diffuse through ATP synthase to
generate ATP.
Oxidative phosphorylation part II:
chemiosmosis

61. This creates an electrochemical
gradient.
The yield of ATP from
chemiosmosis is potentially 32
molecules, but in most conditions
the yield is slightly lower.
Oxidative phosphorylation part II:
chemiosmosis
8.2 U.9 In chemiosmosis protons diffuse through ATP synthase to
generate ATP.

62. After many years the theory was accepted. Peter Mitchell
received the Nobel Prize for Chemistry in 1978
Nature of Science: Paradigm shift—the chemiosmotic theory led to a paradigm
shift in the field of bioenergetics. (2.3)
It takes time for scientists working in a field to accept
paradigm shifts, even when there is strong evidence.
In 1961 Peter Mitchell proposed the chemiosmotic theory.
His ideas explained how synthesis is coupled to
electron transport and proton movement.
His ideas were very different to previous explanations.
http://biologyjunction.com/chemiosmotic_theory.htm
http://www.nobelprize.org/nobel_prizes/chemistry/la
ureates/1978/press.html
Find out more:

63. 8.2 U.10 Oxygen is needed to bind with the free protons to maintain the
hydrogen gradient, resulting in the formation of water.
Oxidative phosphorylation part I:
electron transport chain (ETC)

64. 8.2 U.10 Oxygen is needed to bind with the free protons to maintain the
hydrogen gradient, resulting in the formation of water.
Oxidative phosphorylation part I:
electron transport chain (ETC)

65. A summary of oxidative phosphorylation (8.2.U8 – 8.2.U10)
http://commons.wikimedia.org/wiki/File:2508_The_Electron_Transport_Chain.jpg
http://faculty.nl.edu/jste/electron_transport_system.htm
http://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it
=swf::535::535::/sites/dl/free/0072437316/120071/bio11.swf:
:Electron%20Transport%20System%20and%20ATP%20Synthesi
s
http://www.wiley.com/legacy/college/boyer/047000379
0/animations/electron_transport/electron_transport.ht
m
Use the animations to learn to check your
understanding of oxidative phosphorylation.

66. A summary of oxidative phosphorylation (8.2.U8 – 8.2.U10)
http://commons.wikimedia.org/wiki/File:2508_The_Electron_Transport_Chain.jpg

67. • the electron transport chain is situated on the inner mitochondrial
membrane
• hydrogen is transferred to the electron transport chain by hydrogen
carriers, i.e. NADH and FADH2
• The hydrogen carriers release electrons which are transferred between
carriers this releases energy …
• …. which is used to pump H+ ions (from the matrix) across inner membrane
• H+ ions to accumulate in the inter-membrane space creating a
concentration gradient
• H+ ions return to the matrix through ATP synthase
• Down the electrochemical concentration gradient
• This produces ATP by chemiosmosis
• oxygen is the final electron acceptor for the electron transport chain
• oxygen combines with electrons and H+ ions to produce water
A summary of oxidative phosphorylation (8.2.U8 – 8.2.U10)
http://commons.wikimedia.org/wiki/File:2508_The_Electron_Transport_Chain.jpg

80. 8.2 U.11 The structure of the mitochondrion is adapted to the function it performs.
8.2 S.2 Annotation of a diagram of a mitochondrion to indicate the adaptations to its function.
Annotate the labeled structures:
matrix
Inter-membrane space
ribosomes inner membrane
outer membrane
naked loops of DNA
cristae
http://commons.wikimedia.org/wiki/File:Animal_mitochondrion_diagram_en.svg

81. 8.2 U.11 The structure of the mitochondrion is adapted to the function it performs.
8.2 S.2 Annotation of a diagram of a mitochondrion to indicate the adaptations to its function.
Annotate the labeled structures: matrix
Inter-membrane space
ribosomes inner membrane
outer membrane
naked loops of DNA
fluid containing enzymes  for the
Krebs cycle and the link reaction.
Small space  H+ ions pumped
into the space quickly generate a
high concentration gradient for
chemiosmosis.
Folds in the innner
membrane  increase
surface area available for
oxidative phosphorylation
Synthesises proteins,
including enzymes
used in aerobic
respiration.
Necessary mitochondria
function, including
protein synthesis
contains the contents of the
mitochondrion  enables optimal
conditions for aerobic respiration
contains the integral
proteins that make up the
electron transport chain
and ATP synthase 
electron transport and
chemiosmosis
cristae
http://commons.wikimedia.org/wiki/File:Animal_mitochondrion_diagram_en.svg

82. Bibliography /
Acknowledgments