1. 8.2 Cell respiration Understanding: Skills:
Cell respiration involves the oxidation and reduction of compounds
Phosphorylation of molecules makes them lesson stable
In glycolysis, glucose is converted to pyruvate
Glycolysis gives a small net gain of ATP with out the use of oxygen
In aerobic cell respiration pyruvate is concerted into acetyl coenzyme A
In the Krebs cycle, the oxidation of acetyl groups is coupled to the reduction of hydrogen carriers
Energy released by oxidation reactions is carried to the cristae of the mitochondria
Transfer of electrons between carriers in the electron transport chain is couple to proton pumping
In chemiosmosis protons diffuse through ATP synthase to generate ATP
Oxygen is needed to bind with the free protons to form water to maintain the hydrogen gradient
The structure of the mitochondria is adapted to the function it performs.
Skills:
Annotation of a diagram to indicate the adaptations of a mitochondrion to its function
Applications:
Electron tomography used to produce images of active mitochondria
Nature of science:
- Paradigm shifts: the chemiosmotic theory led to a paradigm shift in the field of bioenergetics

2. What is the role of each part?
Draw a mitochondrion
Inner membrane Outer membrane Cristae Matrix Inter membrane space
What is the role of each part?
Skills:
Annotation of a diagram to indicate the adaptations of a mitochondrion to its function

3. Mitochondrion Drawing
Skills:
Annotation of a diagram to indicate the adaptations of a mitochondrion to its function

4. Mitochondrion Functions
Inner membrane – Electron transport chain and ATP synthase Outer membrane – Creates a cellular compartment Cristae – projections of inner membrane which increase surface area for oxidative phosphorylation Matrix – Contains enzymes for Krebs cycle and link reaction Inter membrane space - Protons pumped into space by electron transport chain. Small space means concentration builds up quickly
Don’t worry. Will will look at all these metabolic processes
Understanding:
The structure of the mitochondria is adapted to the function it performs.

5. Electron Tomography Allows a 3D image of mitochondria to be made
Dr Carmen Mannella:
Cristae are not just infoldings but are defining micro-compartments in the organelle
Cristae are flexible and dynamic – change depending on the metabolism and other stimuli
Specific proteins/lipids that actively regulate the inner membrane
Applications:
Electron tomography used to produce images of active mitochondria

6. Electron Tomography
Changes in internal organization of mitochondria associated with cell death and disease: (A) Normal, isolated liver mitochondrion (B) Liver mitochondrion treated with a protein that induces programmed cell death (C) Mitochondrion from a patient with a mitochondrial myopathy (causes muscle weakness)

7. Oxidation and Reduction
Always occur together
Involve transferring electrons from one thing to another
Oxidation = loss of electrons
Reduction = gain of electrons
For something to gain an electron, something has to lose one.
OIL RIG
Understanding:
Cell respiration involves the oxidation and reduction of compounds

8. Oxidation and Reduction
Understanding:
Cell respiration involves the oxidation and reduction of compounds

9. e.g. Benedict's test Mix in some sugar
Copper sulphate solution contains copper ions – Cu2+
This is a blue solution
The sugar gives the Cu2+ electrons which converts them into Copper atoms–Cu. This forms a red precipitate
What had been oxidised? What has been reduced?

10. Electron Carriers
Electron carriers accept or give up electrons as required – linking oxidations and reductions in cells.
The main electron carrier in respiration is NAD (nicotinamide adenine dinucleotide)
Initially has a positive charge and exists normally as NAD+
What does it look like?

11. Reducing NAD
Two hydrogen atoms removed from substance that is being oxidised?! during respiration (see later)
The first hydrogen is split into a proton and an electron
NAD+ accepts the electron, and the proton (H+) is released
NAD accepts the proton and electron of the second hydrogen atom
Reduction can therefore be the gaining of hydrogen atoms
Oxidation can be losing hydrogen atoms
NAD+ + 2H+ + 2e NADH + H+
NAD+ + 2H NADH + H+
Oxidation can therefore be achieved by losing these Hydrogen atoms again
Understanding:
Cell respiration involves the oxidation and reduction of compounds

12. + H+

13. Oxidation and reduction – describe what is happening below:

14. Phosphorylation
Addition of a phosphate molecule to an organic molecule Make a molecule less stable – so more likely to react Reduces the activation energy required for reactions that follow – more likely to occur
Understanding:
Phosphorylation of molecules makes them less stable

15. Key area = production of ATP
Phosphorylation
Key area = production of ATP
(ADP ATP)
Understanding:
Phosphorylation of molecules makes them less stable

16. Oxidation/Reduction
Phosphorylation

17. Respiration Glycolysis Link Reaction Krebs cycle
Oxidative Phosphorylation
Electron transport chain
Chemiosmosis

18. Glycolysis
Glucose (6C) converted into pyruvate (two) (3C) In the cytoplasm of the cell (outside of mitochondrion) Not a single step process – metabolic pathway 1 glucose 2 pyruvate Reduced NAD (NADH) made (has gained electrons) Phosphorylation of ADP – overall 2 ATP produced
Understanding:
In glycolysis, glucose is converted to pyruvate
Glycolysis gives a small net gain of ATP with out the use of oxygen
In aerobic cell respiration pyruvate is concerted into acetyl coenzyme A

19. “Names of intermediate compounds in glycolysis are not required”
A good example of a metabolic pathway

20. Glycolysis 2 ATP used to phosphorylate one molecule of glucose
Metabolic pathways lead to two molecules of triose phosphate
Each is then oxidised
Hydrogen is accepted by NAD+ to make NADH + H+
Phosphate group transferred to ADP to produce 2 ATP molecules and (two) pyruvate molecule
Understanding:
In glycolysis, glucose is converted to pyruvate
Glycolysis gives a small net gain of ATP with out the use of oxygen

21. Outline the process of Glycolysis (5 marks)
Occurs in the cytoplasm
Glucose is phosphorylated using ATP
Split (lysis) into two triose phosphates
Oxidation of triose phosphates
(two) NAD reduced to NADH (+ H+)
Net gain of two ATP molecules/two ATP use and four ATP produced
(two) Pyruvate at the end of glycolysis

22. The Link Reaction In the mitochondrial matrix
Two molecules of pyruvate produced in glycolysis per molecule of glucose. If oxygen is present (AEROBIC) – pyruvate absorbed into mitochondria where it is oxidised (lose hydrogen atoms). NAD is reduced forming NADH Pyruvate is decarboxylated (Decarboxylated = take away carboxyl group and forms CO2) CO2 removed to form an acetyl group (acetate). Acetyl group then joined to coenzyme A to make acetyl coenzyme A (CoA) How many times does this happen per glucose molecule??
Understanding:
In aerobic cell respiration pyruvate is concerted into acetyl coenzyme A

23. Link reaction - links glycolysis with the Krebs cycle
The Link Reaction
Link reaction - links glycolysis with the Krebs cycle
Krebs Cycle
Happens twice per glucose molecule

24. The Krebs
Cycle
The CoA goes back to be reused in the link reaction
Acetyl CoA (2C) from link reaction combines with a 4 carbon compound, making a 6 carbon compound.
This is oxidized and decarboxylated to form a 5 carbon compound. Carbon is released and combines with oxygen to form carbon dioxide. NAD+ is reduced to NADH 1. 2.
Understanding:
In the Krebs cycle, the oxidation of acetyl groups is coupled to the reduction of hydrogen carriers
Energy released by oxidation reactions is carried to the cristae of the mitochondria

25. The Krebs
Cycle
3. The 5 carbon compound is oxidized and decarboxylated to form a 4 carbon compound. This forms carbon dioxide and another NADH
4. The 4 carbon compound undergoes various changes resulting in more products:
FAD to FADH2
NAD to NADH
ADP to ATP 4. 3.
What is happening in these situations?
Understanding:
In the Krebs cycle, the oxidation of acetyl groups is coupled to the reduction of hydrogen carriers
Energy released by oxidation reactions is carried to the cristae of the mitochondria

26. The Krebs Cycle
Must spin twice for each glucose molecule as two pyruvates are formed in glycolysis.
Every 1 glucose molecule (2 spins) produces:
6 NADH (oxidation and reduction) of?
4 CO2 (decarboxylation)
2 FADH2 (oxidation and reduction) of?
2 ATP (phosphorylation)
Substrate* phosphorylation – ATP produced
Energy stored in NADH and FADH passed on to the final part of respiration: oxidative phosphorylation (electron transport chain)
Half of these per spin
Understanding:
In the Krebs cycle, the oxidation of acetyl groups is coupled to the reduction of hydrogen carriers
Energy released by oxidation reactions is carried to the cristae of the mitochondria

27. The Krebs Cycle
By the end of the Krebs cycle, only 4 ATPs have been gained.
4 from glycolysis (but 2 used up in the process)
2 from Krebs cycle
All by substrate level phosphorylation*
During respiration a total of 36 ATPs gained overall from 1 glucose molecule. (32 produced in the Electron transport chain and chemiosmosis)
Understanding:
In the Krebs cycle, the oxidation of acetyl groups is coupled to the reduction of hydrogen carriers
Energy released by oxidation reactions is carried to the cristae of the mitochondria

28. Phosphorylation
What we have seen so far
Substrate level: ATP produced via transport of phosphate group directly to ADP Oxidative: Oxidative phosphorylation is the metabolic pathway in which cells use enzymes to oxidise compounds (reduced NAD and reduced FAD), thereby taking energy to the electon transport chain which is used to form ATP.
Understanding:
Phosphorylation of molecules makes them less stable

30. Oxidative Phosphorylation - Electron Transport Chain and Chemiosmosis
Across the inner membrane
Series of small steps, carried out by a chain of electron carriers. Generates ATP with the energy from previous oxidation reactions* *
FADH2 also
Understanding:
Transfer of electrons between carriers in the electron transport chain is couple to proton pumping
In chemiosmosis protons diffuse through ATP synthase to generate ATP
Oxygen is needed to bind with the free protons to form water to maintain the hydrogen gradient

31. Oxidative Phosphorylation - Electron Transport Chain and Chemiosmosis
Across the inner membrane
NADH is oxidised and releases 2 hydrogen artoms. NAD returns to matrix. Both H atoms split into H+ and e-.
The electrons move down the electron transport chain via electron carriers (membrane proteins), losing energy at each one.
This provides the carriers with energy to pump protons (H+) into the intermembrane space.
A concentration gradient of proteins builds up. 4. 2. 1.
FADH2 also 3.

32. Oxidative Phosphorylation - Electron Transport Chain and Chemiosmosis
Across the inner membrane
5. In order for electrons to carry on flowing they must be transferred to a terminal electron acceptor – oxygen which becomes O2- (gets reduced), but then combines with two H+ (from the matrix) to form water. By using up H+ the proton gradient across the inner membrane is maintained 6. Protons pass from the intermembrane space, through ATP synthase, into the matrix. As they move down their concentration gradient, energy is released and used by ATP synthase to phosphorylate ADP to ATP. 6. 5. _
FADH2 also

33. How many ATP molecules are made from one glucose molecule?

34. How many ATP molecules are made from one glucose molecule?

35. Respiration Step 1: Mitochondria Step 2: Steps in respiration 1. 2. 3.4. 5.
Step 3:
Step 4 & 5:

36. Create a respiration diagram
Use a piece of A3/A4 paper
Create a respiration diagram – go step by step from the start.
Include:
Glycolysis
Link reaction
Krebs cycle
Oxidative phosphorylation
Electron transport chain
Chemiosmosis
Where do they happen
Is reduced NAD/FAD produced
Is ATP produced
What is made from that process
What happens here
Is it substrate level phosphorylation or oxidative phosphorylation

38. 8 marks
Explain the process of aerobic respiration including oxidative phosphorylation.

39. glucose converted to pyruvate (two molecules);
by glycolysis;
pyruvate enters the mitochondria;
pyruvate converted to acetyl CoA;
by oxidation and decarboxylation / NADH and CO2 formed;
acetyl CoA enter the Krebs cycle (by link reaction);
FAD / NAD+ reduced to NADH / FADH2;
FADH2 / NADH donates electrons to electron transport chain (reject donates H+);
electrons release energy as they pass along the chain;
oxygen final electron acceptor;
production of water;
builds up proton gradient/protons pumped across inner membrane;
protons flow into matrix of mitochondria through ATPase / ATP synthase;
ATP produced;
produces 36 / 38 ATP (per glucose); 8 max Accept any appropriate terminology for NAD and FAD. (Plus up to [2] for quality)

40. Respirometers

41. Anaerobic Respiration
Does not use oxygen
Only gets as far as glycolysis
Produces lactate (lactic acid)
+2 ATP
The production of lactate regenerates NAD. This means glycolysis can continue
2 ATP produced per glucose

42. Breakdown of lactic acid in animals
Cells convert the lactic acid back into pyruvate (which re-enters aerobic respiration when oxygen is present)
Liver cells can convert the lactic acid back into glucose (which can be respired or stored)