1. CELLULAR RESPIRATION
BIOLOGY IB/ SL
Option C.3

2. BIOCHEMICAL REACTIONS
All living organisms require a constant supply of energy to sustain life.
Cellular respiration - the chemical energy stored in glucose is converted into a more usable form – ATP
Requires the presence of oxygen and the correct enzymes
Carbon dioxide, water and heat are also released as by-products of this reaction.
C6H12O O2 → 6 CO H2O + energy (ATP + heat)
glucose + oxygen → carbon + water + energy
dioxide
. In cells control the release of chemical-bond energy from organic molecules (such as glucose) through enzyme controlled chemical reactions

3. Oxidation / Reduction
Oxidation involves the loss of electrons from an element; oxidation frequently involves gaining oxygen or losing hydrogen
Reduction involves a gain of electrons; and that reduction frequently involves losing oxygen or gaining hydrogen

4. Cellular respiration is an example of a Redox reaction as shown in the chemical equation below

5. NAD+ electron carrier Nicotinamide adenine dinucleotide
Coenzyme, oxidizing agent, reduced form is NADH
NADH carries electrons to ETC

6. Adenosine triphosphate /ATP
Section 8-1
Adenine
Ribose
3 Phosphate groups
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7. PHOSPHORYLATION OXIDATIVE ATP synthesis powered by redox reactions
Electron transport chain
Requires oxygen (final electron acceptor)
SUBSTRATE LEVEL
ATP synthesis from transfer of phosphate group from substrate to ADP
Glycolysis and Krebs cycle

8. Storing energy by substrate level phosphorylation
Figure 8-3 Comparison of ADP and ATP to a Battery
Storing energy by substrate level phosphorylation
Section 8-1
ADP
ATP
Energy
Energy
Adenosine diphosphate (ADP) + Phosphate
Adenosine triphosphate (ATP)
Partially
charged
battery
Fully
charged
battery
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9. Substrate level Phosphorylation in glycolysis

10. Stages of Cellular Respiration
GLYCOLYSIS
First pathway in a cell getting energy out of food. Breaks glucose into pyruvic acid and ATP.
Takes place in the cytoplasm
Releases only a small amount of energy
Will happen with or without oxygen
2. KREBS CYCLE
Happens in the mitochondrial matrix
Only takes place if oxygen is present
3. ELECTRON TRANSPORT CHAIN (Oxidative phosphorylation)
Happens in the inner mitochondrial membrane

11. Respiration/ overview
Biology: Life on Earth (Audesirk)
Respiration/ overview
FIGURE 8-1 A summary of glucose metabolism
Chapter 8
Harvesting Energy

12. Glycolysis glucose  pyruvate; cytosol

13. Krebs cycle mitochondrial matrix, pyruvate acetyl CoA & CO2

15. GLYCOLYSIS
In glycolysis a 6C glucose molecule is broken into 2 (3C) molecules of pyruvate (pyruvic acid)
Glycolysis occurs in the cytoplasm of the cell – near the mitochondria
Yields are:
+ 2 ATP (4 ATP – 2ATP - used to phosphorylate glucose when it enters cell)
2 NADH (NAD+ is reduced to NADH)
This process is anaerobic (without oxygen)…can happen even if there is an insufficient O2 level to carry out the rest of cellular respiration

16. To the electron transport chain
Glycolysis
Section 9-1
Glucose
2 Pyruvic acid
To the electron transport chain
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17. Fermentation or aerobic respiration?

18. FERMENTATION
Under anaerobic conditions, pyruvate is converted into lactate or ethanol, a process called fermentation
Fermentation does not produce more ATP, but is necessary to regenerate/ recycle the high-energy electron carrier molecule NAD+, which must be available for glycolysis to continue

19. LACTIC ACID FERMENTATION

20. ALCOHOLIC FERMENTATION

21. Fermentation of Dough
Explain how does the dough rise?
Chapter 8

22. Mitochondrial structure
Double membrane-bound organelle
Inner membrane folded into christae
a) Increase surface area for reactions
b) ETC located here
3) Intermembrane space
4) Matrix - Kreb’s cycle

23. Structure of the mitochondria as seen under TEM

24. DOUBLE MEMBRANE ORGANELLES
In eukaryotic cells, cellular respiration occurs within mitochondria, organelles with two membranes that have two compartments.
The inner membrane encloses a central compartment containing the fluid matrix
The outer membrane surrounds the organelle, producing an intermembrane space
Chapter 8

25. LINK RECTION (Oxidation of Pyruvate)
Occurs in mitochondrion, requires transport protein & coenzyme A
Yields Acetyl CoA, 1 NADH & 1 H+ from each pyruvate (2 total)
Waste – carbon dioxide

26. LINK REACTION

27. KREBS CYCLE

28. Electron transport chain (ETC)
- Electrons from reduced coenzymes NADH and FADH2 are transferred through a series of redox reactions from one carrier to another located in the inner mitochondrial membrane until the electrons are accepted by oxygen to make water. - Every time the electron is passed, some of its energy is released and can be used to make ATP - The rest of the energy is released as heat
High-energy electrons, such as those made when light strikes a chlorophyll molecule, are passed from one carrier molecule to another along a chain, like a hot potato. Every time the electron is passed, some of its energy is released and can be used to build an ATP. There is a stepwise passage of energy from molecule to molecule. Some of this bond energy is put into the ATP bond. The rest of this energy is released as heat.

29. Electron Transport Chain
Section 9-2
Electron Transport
Hydrogen Ion Movement
Channel
Intermembrane
Space
ATP synthase
Inner
Membrane
Matrix
ATP Production
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30. CHEMIOSMOSIS
Energy is released from electrons as they are passed down the electron transport chain
Released energy used to pump hydrogen ions across the inner membrane
Hydrogen ions accumulate in intermembrane space
Hydrogen ions form a concentration gradient across the membrane, a form of stored energy
Hydrogen ions flow back into the matrix through an ATP synthesizing enzyme
Process is called chemiosmosis
Chapter 8

31. CHEMIOSMOSIS Energy coupling ATP synthase
Generates ATP
Molecular mill
Powered by proton flow
Uses exergonic flow of electrons to pump H+ (protons) from matrix into intermembrane space, they flow back through ATP synthase
H+ gradient couples redox reactions of ETC to ATP synthesis

32. ATP Synthase Enzyme along inner mitochondrial membrane
Uses electrochemical potential energy to drive phosphorylation
Proton-motive force

33. Mitochondrial Chemiosmosis (1)
Chapter 8

34. Mitochondrial Chemiosmosis (2)
Mitocondrial chemoosmosis 2
Mitochondrial Chemiosmosis (2)
Chapter 8

35. Mitochondrial Chemiosmosis (3)
Chapter 8

36. ETC produces: (per glucose)
2 NADH (from glycolysis)
2 NADH (from intermediate reactions) +
6 NADH (Krebs cycle)______________
10 NADH x 3 ATP/NADH = 30 ATP
2 FADH2 x 2 ATP/ FADH2 = 4 ATP____
for a total 34 ATP/glucose from ETS

37. Cellular Respiration Energy Summary
34 ATP/glucose from ETS +
2 ATP (glycolysis) +
2 ATP (Krebs cycle)_______________
38 ATP per glucose!!!
Draw on board. Remark at end about NADH from glycolysis only making 2/molecule

39. Influence on How Organisms Function
Metabolic processes in cells are heavily dependent on ATP generation (cyanide kills by preventing this)
Muscle cells switch between fermentation and aerobic cell respiration depending on O2 availability
Chapter 8