1. Cellular Respiration (Cell. Resp.)
Notes
Cellular Respiration (Cell. Resp.)

2. 6.1 Energy
Energy captured from sun rays through photosynthesis (plants, algae, protists, and bacteria)
makes glucose from CO2 and H2O with release of O2
These & consumers use the O2 and energy in sugar and release CO2 and H2O

3. Overview of Energy Flow food  ATP  cell work

4. 6.1 Sunlight energy ECOSYSTEM Photosynthesis in chloroplasts Glucose
Cellular respiration
in mitochondria
H2O
CO2 O2 +
(for cellular work)
ATP
Heat energy
Figure 6.1 The connection between photosynthesis and cellular respiration.

5. 6.2 Breathing vs. Cellular Respiration
Breathing - exchanges CO2 produced during cell. resp. for O2
Cellular respiration - uses O2 to get energy from glucose and produces CO2 O2
CO2
Lungs
CO2 O2
Bloodstream
Muscle cells carrying out
Cellular Respiration
6.2
Glucose + O2
CO2 + H2O + ATP

6. 6.3 Cellular Respiration is Exergonic
Transfers energy from the bonds in glucose to ATP
Cell. resp. produces ~ ATP molecules from each glucose molecule
Other foods can be used too
6.3
C6H12O6
+ 6 O2
Glucose
Oxygen 6
CO2
Carbon
dioxide
H2O
Water +
ATPs
Energy

7. 6.4 Caloric Needs
The average adult human needs ~ 2,200 kcal (called Calories on food labels) of energy per day
kilocalorie (kcal) - the amount of heat needed to raise the temp. of 1 kg of water by 1oC
energy comes from the metabolism of food during cell. resp.

8. Table 6.4 Energy Consumed by Various Activities (in kcal).

9. 6.5 Chemical Energy
Energy is contained in the arrangement of electrons in chemical bonds.
When the carbon-hydrogen bonds of glucose are broken, electrons are transferred to oxygen (O)
O has a relatively high electronegativity
Moving atoms releases energy in the bonds

10. 6.5 Chemical Energy Energy can be released from glucose by burning it
energy dissipates as heat and light, not available to living organisms

11. 6.5 Cellular Respiration The controlled breakdown of organic molecules
Energy is released in small amounts & can be captured and stored in ATP

12. 6.5 Cellular Respiration
Remember a H atom is one electron and one proton…we will see oxidation and reduction as the moving of a H atom
Loss of electrons (or H) is called oxidation
Gain of electrons (or H) is called reduction

13. At the same time, O2 gains H atoms (reduction) and is converted to H2O
C6H12O O2
Glucose
Loss of hydrogen atoms
(oxidation)
6 CO H2O Energy
Gain of hydrogen atoms
(reduction)
(ATP)
Glucose loses its H atoms (oxidation) and is ultimately converted to CO2
At the same time, O2 gains H atoms (reduction) and is converted to H2O
Figure 6.5A Rearrangement of hydrogen atoms (with their electrons) in the redox reactions of cellular respiration.

14. 6.5 Role of Enzymes
Enzymes are needed to oxidize glucose & other foods
enzyme that removes hydrogen from an organic molecule is called dehydrogenase
requires a coenzyme called NAD+ (nicotinamide adenine dinucleotide) to shuttle electrons
NAD+ can become reduced when it accepts electrons and oxidized when it gives them up

15. Oxidation
Dehydrogenase
Reduction
NAD+
+ 2 H
NADH + H+
(carries
2 electrons)
2 H e–

16. 6.5 NAD+ / NADH
The transfer of electrons to NAD+ (an electron acceptor) creates NADH (an electron donor), the reduced form of NAD+
Donor
Acceptor
Electrons are removed, transferred, and accepted in pairs.
Student Misconceptions and Concerns
1. Students should be cautioned against the assumption that energy is created when it is converted from one form to another. This might be a good time to review the principle of conservation of energy (the first law of thermodynamics addressed in Module 5.11).
2. The advantage of the gradual degradation of glucose may not be obvious to some students. Many analogies exist that reveal the advantages of short and steady steps. Fuel in an automobile is burned slowly to best utilize the energy released from the fuel. A few fireplace logs release gradual heat to keep a room temperature steady. In both situations, excessive use of fuel becomes wasteful, reducing the efficiencies of the systems.

17. 6.5 Cells tap energy from electrons “falling” from organic fuels to oxygen
There are other electron “carrier” molecules that function like NAD+
They form a staircase where the electrons pass from one to the next down the staircase
These electron carriers collectively are called the electron transport chain, and as electrons are transported down the chain, ATP is generated
Electron transport occurs in the cell’s inner membrane of a mitochondrion.
The final electron acceptor is oxygen, and the product of this reaction is water.
Student Misconceptions and Concerns
1. Students should be cautioned against the assumption that energy is created when it is converted from one form to another. This might be a good time to review the principle of conservation of energy (the first law of thermodynamics addressed in Module 5.11).
2. The advantage of the gradual degradation of glucose may not be obvious to some students. Many analogies exist that reveal the advantages of short and steady steps. Fuel in an automobile is burned slowly to best utilize the energy released from the fuel. A few fireplace logs release gradual heat to keep a room temperature steady. In both situations, excessive use of fuel becomes wasteful, reducing the efficiencies of the systems.

18. 6.5 NADH ATP NAD+ + 2e– Controlled release of H+ energy for synthesis
of ATP H+
Electron transport
chain
Figure 6.5C In cellular respiration, electrons fall down an energy staircase and finally reduce O2.
2e– H+ 1  2 O2
6.5
H2O

19. 6.6 Cellular Respiration
Definition- the stepwise biochemical process that extracts energy from food in cells to create ATP
Who does it? EUKARYOTIC organisms
Types: Aerobic (uses O2) or anaerobic (does not use O2)
Where does it occur? Aerobic – starts in the cytoplasm and finishes in the mitochondria; Anaerobic – in the cytoplasm

20. 6.6 Aerobic Respiration
Most plants and animals use aerobic respiration as their primary means for synthesizing ATP; usually producing approximately ATP per glucose
The equation used by these organisms is:
C6H12O6 + 6O2  6CO2 + 6H2O + ATP
Glucose + oxygen  carbon + water + energy
dioxide

21. How efficient is the process of cellular respiration?
The ATP molecules the cell makes per glucose represents 38-40% of the total energy of glucose
The remaining 60-62% is released as heat

22. Importance of Glucose Monomer for carbohydrates
Stored in liver of animals
Carried to the cells by the bloodstream
Fuel for cellular respiration
Stores energy in the bonds between atoms

23. Anaerobic Conditions No O2 present
Less efficient and produces less ATP (usually 2 per glucose)
Used by many bacteria and protists
Can occur in humans (especially used during exercise –we will come back to this idea)

24. 3 Steps of Aerobic Resp.

25. 6.6 Overview of Aerobic Resp.
1. Glycolysis – break glucose apart
2. Kreb’s/Citric Acid Cycle – release CO2
3. Electron Transport System/Chain & Oxidative Phosphorylation – makes most of the ATP