1. Cellular Respiration
BIOLOGY

2. What is Cellular Respiration?
Step-by-step breakdown of high-energy glucose molecules to release energy
Takes place day and night in all living cells
Occurs in stages, controlled by enzymes

3. Where does it occur? In the Cell Mitochondrion Outer Membrane
Inner Membrane

4. Different types of Cellular Respiration
Anaerobic respiration
Usually occurs when there is no oxygen available
When partially breaking down glucose, this process releases a very small amount of energy.
Aerobic respiration
Occurs in the presence of oxygen
When chemically breaking down glucose completely, this process releases large amounts energy

5. Stage 1: Glycolysis
means "splitting sugars" ….6 carbon glucose is split into two 3 carbon molecules (pyruvate)
Occurs in the cytoplasm of cells
With or Without O2 not required (anaerobic)
Some ATP produced
Net yield = 2 ATPs

6. The Krebs Cycle (a.k.a. citric acid cycle)
Occurs in the mitochondria
O2 required (aerobic)
CO (waste)
Some ATP produced
Net yield = 2 ATPs

7. SUMMARY OF THE KREBS CYCLE
6 NADH
GLYCOLYSIS
2 FADH2
CoA
Krebs
cycle
acetyl coenzyme A
CO2
2 ATP
electron
transport
chain 1.
oxaloacetic acid
citric acid
NAD+
NADH
NADH
NAD+ 2. 6.
CO2
a-ketoglutaric acid
malic acid
Figure: 07-08
Title:
Summary of the Krebs cycle.
Caption:
The Krebs cycle is the major source of electrons that are transported to the electron transport chain by the electron carriers NADH and FADH2. For each molecule of glucose, two molecules of acetyl coenzyme A enter the Krebs cycle. Through a series of reactions, a total of 6 NADH, 2 FADH2, and 2 ATP are produced per glucose molecule. (From counting the number of NADH and FADH2 around the cycle, it would appear that only 3 NADH and 1 FADH2 are produced, but remember that one molecule of glucose results in two “trips” around the cycle, as two molecules of acetyl coenzyme A will enter the Krebs cycle for every molecule of glucose that is metabolized.) 3.
CO2
FADH2
FAD+
NAD+
NADH 5.
ADP 4.
a-ketoglutaric acid
derivative
succinic acid
ATP

8. Electron Transport Chain
series of electron carriers in the membrane of the mitochondria
Occurs in the inner membrane of mitochondria
O2 required (aerobic)
A lot of ATP produced
Net yield = 32 ATPs
Krebs Cycle

9. ELECTRON TRANSPORT CHAIN
GLYCOLYSIS
mitochondrion
KREBS
CYCLE
inner
membrane
ELECTRON
TRANSPORT
CHAIN 32
ATP
inner compartment O2
H2O
outer compartment
outer
compartment
ATP SYNTHESIS H+ H+ H+ H+ H+
inner
membrane H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+
Figure: 07-09
Title:
The electron transport chain.
Caption:
The movement of electrons through the ETC powers the process that provides the bulk of the ATP yield in respiration. The electrons carried by NADH and FADH2 are released into the ETC and transported along its chain of molecules. The movement of electrons along the chain releases enough energy to power the pumping of hydrogen ions (H+) across the membrane into the outer compartment of the mitochondrion. It is the subsequent energetic “fall” of the H+ ions back into the inner compartment that drives the synthesis of ATP molecules by the enzyme ATP synthase. H+ H+
NADH H+
ATP
synthesis
NAD+
2 H+ + 1/2 O2
ADP + P
inner
compartment
H2O
ATP
ELECTRON TRANSPORT CHAIN

10. Cellular Respiration Review…...
Q. Where does each Stage occur?
3 Stages:
Stage 1: Glycolysis
O2 not required (anaerobic)
Some ATP produced
Stage 2: Krebs Cycle
O2 required (aerobic)
Stage 3: Electron Transport System
Much ATP produced
A. Cytoplasm of the cell
2 ATPs
Mitochondrion
(matrix)
2 ATPs
A. Mitochondrial
innermembrane
TOTAL: 36ATP
32 ATPs

11. GLYCOLYSIS 2 energy tokens GLYCOLYSIS mitochondrion cytosol (ATP) -
reactants
products
glucose
GLYCOLYSIS
2 ATP
Insert 1 Glucose
2 energy
tokens
2 NADH
GLYCOLYSIS
mitochondrion
cytosol
(ATP)
glucose derivatives -
carbon dioxide
2 NADH
2 energy
tokens
carbon
dioxide -
KREBS
CYCLE
KREBS
CYCLE - -
6 NADH
2 ATP
2 FADH2
Figure: 07-04a-b
Title:
Overview of energy harvesting.
Caption:
a. In metaphorical terms. Just as the video games in some arcades can use only tokens (rather than money) to make them function, so our bodies can use only ATP (rather than food) as a direct source of energy. The energy contained in food is transferred to ATP in three major steps: glycolysis, the Krebs cycle, and the electron transport chain. Though glycolysis and the Krebs cycle contribute only small amounts of ATP directly, they also contribute electrons (on the left of the token machine) that help bring about the large yield of ATP in the electron transport chain. b. In schematic terms. As with the arcade machine, the starting point in this example is a single molecule of glucose, which again yields ATP in three major sets of steps: glycolysis, the Krebs cycle and the electron transport chain (ETC). These steps can yield a maximum of 36 molecules of ATP: 2 in gylcolysis, 2 in the Krebs cycle, and 32 in the ETC. As noted, however, glycolysis and the Krebs cycle also yield electrons that move to the ETC, aiding in its ATP production. These electrons get to the ETC via the electron carriers NADH and FADH2, shown on the left. Oxygen is consumed in energy harvesting, while water and carbon dioxide are produced in it. Glycolysis takes place in the cytosol of the cell, but the Krebs cycle and ETC take place in the cellular organelles called mitochondria. - -
32 energy
tokens -
ELECTRON
TRANSPORT
CHAIN
ELECTRON
TRANSPORT
CHAIN -
32 ATP
Oxygen
Water

12. Aerobic Respiration
Oxygen combines with glucose to convert it into energy
Releasing carbon dioxide and water as waste products.
glucose + oxygen  carbon dioxide + water + lots of heat energy

13. Anaerobic Respiration
Occurs if there is a lack of oxygen available for aerobic respiration
Glucose is incompletely broken down
In this type of respiration a lot less energy is produced and most of it is lost as heat.

14. Anaerobic Energy Production: Fermentation
Lactic Acid
Formed mainly by animal muscle cells
Occurs in some unicellular organisms
Glucose  lactic acid + a tiny amount of heat energy
Alcoholic Fermentation
Yeast cells, Bacteria
Glucose  alcohol + carbon dioxide + a tiny amount of heat energy

15. Summary: Aerobic & Anaerobic
Similarities:
Glucose is broken down.
Carbon dioxide is released.
Energy is liberated.
Differences:
Aerobic respiration
Anaerobic respiration
Lots of energy released
Little energy is released
Water is the end product
Lactic Acid or alcohol is the end product
Glucose is completely broken down
Glucose is partially broken down
Is dependent on oxygen
Is not dependent on oxygen