1. Cell Respiration
Topic 2.8 and 8.1

2. Cell Respiration Is used by all cells to produce ATP
Organic molecules contain energy
Each covalent bond represents stored chemical energy
Cells perform slow oxidation (act of burning/breaking covalent bonds)
Molecule is acted upon by a series of enzymes
Trap released energy in ATP molecules

3. Cell Respiration
Cell Respiration--controlled release of energy from organic compounds in cells to form ATP
Aerobic Cellular Respiration a metabolic pathway with over 20 reactions, using 20 enzymes

4. Oxidation and Reduction
Loss of electrons
Gain of electrons
Gain of oxygen
Loss of oxygen
Loss of hydrogen
Gain of hydrogen
Results in many C-O bonds
Results in many C-H bonds
Results in a compound with lowers potential energy
Results in a compound with higher potential energy
LEO goes GER
Lose Electrons Oxidized
Gain Electrons Reduced

5. Mitochondrion--Structure and Function 2 phospholipids bilayers with embedded protein

6. Aerobic Cellular Respiration C6H12O6 + 6O2 --> 6CO2 + 6H2O

7. Glycolysis
Two molecules of ATP are used to begin. The phosphates from the ATPs phosphorylate glucose to form fructose-1,6-bisphosphate.
6- carbon glucose
2 ATP
2 ADP P P
Substrate-level Phosphorylation

8. Glycolysis
The 6C phosphorylated fructose is split into two 3C sugars called glyceraldehyde – 3 – phosphate (G3P) P P
Lysis P P
Glyceraldehyde – 3 – phosphate
Glyceraldehyde – 3 – phosphate

9. Glycolysis
Entering the oxidation phase: ATP formation and production of the reduced coenzyme NAD. As NADH is being formed, released energy is used to add an inorganic phosphate. Phosphates are removed, creating pyruvate.
Substrate-level phosphorylation 2 P P P P 2 2 2
G3P
pyruvate
2NAD+
2 NADH
4 ADP
4 ATP
Oxidation

10. Glycolysis Summary Two ATPs are used to start the process
A total of four ATPs are produced – a net gain of two ATPs
Two molecules of NADH are produced
Involves substrate – level phosphorylation, lysis, oxidation and ATP formation
Occurs in the cytoplasm of the cell
This metabolic pathway is controlled by enzymes
Two pyruvate molecules are present at the end of the pathway

11. Anaerobic Respiration
‘Cell Respiration’ – refers to a variety of biochemical pathways that can be used to metabolize glucose
All the pathways start with GLYCOLYSIS
Occurs in an anaerobic environment
Without oxygen
Breaking down organic molecules in an anaerobic environment is FERMENTATION

12. Alcoholic Respiration
Yeast use alcoholic respiration for ATP production
Use in Bread and Alcoholic production
CO2
Pyruvate 3C
Ethanol 2C
Glucose 6C
CO2
Pyruvate 3C
Ethanol 2C
Glycolysis
Net gain of 2 ATP

13. Lactic Acid Fermentation
Aerobic cells (like our muscle cells) can be starved of oxygen (like when exercising) and enter anaerobic respiration
Benefit?
Allows glycolysis to continue with the small gain of ATP (even if the aerobic pathway is not accessible)
Pyruvate 3C
Lactate 3C
Glucose 6C
Reaction reversible when oxygen available
Lactate 3C
Pyruvate 3C
Net gain of 2 ATP
Aerobic Pathway
(lots of ATP made)

14. Aerobic is more efficient
Anaerobic
Breaks down glucose completely
Partial breakdown
End products: CO2 and H2O
End Products: ethanol and lactic acid
Large yield of ATP (34-38)
Low yield of ATP (only 2)

15. Link Reaction
Pyruvate enters the matrix of the mitochondria via active transport
CO2 is released as a waste gas
Acetyl group is oxidized while reducing NAD+
Acetyl group combines with coenzyme A (CoA) to form Acetyl CoA
CoA acts as a transport to get Acetyl to the Kreb’s cycle
Reaction is controlled by enzymes

16. Kreb’s Cycle Acetyl CoA: Kreb’s Cycle
Can be produced from most carbohydrates and fats
Can be synthesized into a lipid for storage
Occurs with ATP levels are high
Kreb’s Cycle
When ATP is needed, acetyl CoA enters the cycle
Occurs in the matrix of the mitochondria

17. Krebs Cycle
Acetyl CoA from the link reaction combines with a 4C compound called oxaloacetate. The result if a 6C compound called citrate
Acetyl-CoA
- CoA
CoA
Oxaloacetate 4C
Citrate 6C

18. Krebs Cycle
Citrate (6C compound) is oxidized to form a 5C compound. In this process, the carbon is released from the cell (after combining with oxygen) as CO2. While the 6C compound is oxidized, NAD+ is reduced to form NADH
Acetyl CoA
CoA 4C 6C
CO2
NAD+
NADH 5C

19. Krebs Cycle
The 5C compound is oxidized and decarboxylated to form a 4C compound. Again, the removed carbon combines with oxygen and is released as CO2. Another NAD+ is reduced to form NADH.
Acetyl CoA
CoA 4C 6C
CO2
NAD+ 5C
NADH
CO2 4C
NAD+
NADH

20. Krebs Cycle
The 4C compound undergoes various changes resulting in several products. One product is another NADH. The coenzyme FAD is reduced to from FADH2. There is also a reduction of an ADP to form ATP. The 4C compound is changed during these steps to re-from oxaloacetate.
Acetyl CoA
CoA 4C 6C
NADH
CO2
oxaloacetate
NAD+
NAD+ 5C
NADH
FADH2
CO2
FAD 4C
NAD+
ATP
ADP + Pi
NADH

21. Kreb’s Cycle Summary For each glucose, the cycle runs TWICE Products
2 ATP molecules
6 NADH molecules (allow energy storage and transfer)
2 FADH2 molecules
4 CO2 molecules

22. Electron Transport Chain
Where most of ATP is created
Oxygen is needed
Occurs in Mitochondria, on inner membrane and cristae
Within the membranes are molecules
These carriers of electrons pass electrons from one to another due to an energy gradient, due to electronegativity.
As electrons move down the chain of molecules, energy is released.

23. Electrons are provided by coenzymes NADH and FADH2
Carriers:
FMN: protein carrier has a flavin-containing group
Cyt: Cytochromes (iron-containing proteins)
CoQ: Coenzyme Q (ubiquinone) is not a protein
Each Movement releases energy
Note: FADH2 enters later in the chain, which means less energy is given, therefore fewer ATPs are produced
NADH: 3 ATPs
FADH2: 2 ATPs
At the end of chain, de-energized electrons are accepted by oxygen

24. Chemiosmosis
Involves the movement of protons (H+) to provide energy so that phosphorylation can occur – oxidative phosphorylation
As e- is moved to each protein, the energy released sends H+ against gradient
H+ pass back through ATP synthase creating the energy needed to attach an inorganic phosphate to ADP

25. Inner Membrane Space Inner Membrane Matrix
2. Using the small amount of energy released, H+ are pushed against concentration gradient
3. As H+ concentration gets to be too high, H+ passively move through the ATP synthase
Inner Membrane Space
Inner Membrane
4. As H+ passes through, ATP synthase spins, this creates the energy needed to attach the P to the ADP making ATP
Matrix
1. e- flow through chain, releasing small amount of energy
Oxygen is the final e- acceptor creating water
Protons available to move against gradient

26. C6H12O6 + 6O2 --> 6CO2 + 6H2O+ energy
Stage
Location
Reactants
Products
ATP molecules
Glycolysis
cytosol
1 Glucose,
2 ATP, 4ADP,
2 NAD +
2 Pyruvate
4 ATP
2 NADH 2
Link Reaction
Upon entering mitochondrion
2 pyruvate
2 CoenzymeA
2 Acetyl CoA
2 CO2
Krebs Cycle
Mitochondria
matrix
6 NAD +
2 FAD, 2 ADP
4 CO2
6 NADH
2 FADH ATP
Electron Transport Chain
Cristae (inner membrane)
10 NADH
2 FADH2
6O2
34 ATP
6H2O 34

29. Final Look Structure Function Outer Mitochondrial Membrane
Separates the contents of the mitochondrion from the rest of the cell
Matric
Internal cytosol-like area that contains the enzymes for the link reaction and the Kreb’s cycle
Cristae
Tubular regions surrounded by membranes increasing surface area for oxidative phosphorylation
Inner mitochondrial membrane
Contains the carriers for the electron transport chain and ATP synthase for chemiosmosis
Inner membrane space
Reservoir for hydrogen ions (protons), the high concentration of hydrogen ions is necessary for chemiosomosis