1. Cellular Respiration Harvesting Chemical Energy
ATP

2. “Burn fuels” to make energy
combustion
making heat energy by burning fuels in one step
CO2 + H2O + heat
fuel (carbohydrates) O2
aerobic respiration
making ATP energy (& some heat) by burning fuels in many small steps
Movement of hydrogen atoms from glucose to water
ATP
food (carbohydrates) O2
ATP + CO2 + H2O (+ heat)

3. Energy needs of life Animals are energy consumers
What do we need energy for?
synthesis (building for growth)
reproduction
active transport
movement
temperature control (making heat)
Which is to say… if you don’t eat, you die… because you run out of energy.
The 2nd Law of Thermodynamics takes over!

4. Where do we get energy? ATP Energy is stored in organic molecules
carbohydrates, fats, proteins
Animals eat these organic molecules  food
digest food to get
fuels for energy (ATP)
raw materials for building more molecules
carbohydrates, fats, proteins, nucleic acids
ATP
We eat to take in the fuels to make ATP which will then be used to help us build biomolecules and grow and move and… live!
heterotrophs = “fed by others”
vs.
autotrophs = “self-feeders”

5. Adenosine TriPhosphate
What is energy in biology?
ATP
Adenosine TriPhosphate

6. Harvesting energy stored in food
Cellular respiration
breaking down food to produce ATP
in mitochondria
using oxygen
“aerobic” respiration
usually digesting glucose
but could be other sugars, fats, or proteins
ATP
food O2
Movement of hydrogen atoms from glucose to water
glucose + oxygen  energy + carbon + water
dioxide
C6H12O6
6O2
ATP
6CO2
6H2O  +

7. Turn to your partner and…
Discuss sources of energy
Discuss organelle where ATP is produced
Why is cellular respiration considered “aerobic”?

8. What do we need to make energy?
The “Furnace” for making energy
mitochondria
Fuel
food: carbohydrates, fats, proteins
Helpers
oxygen
enzymes
Product
ATP
Waste products
carbon dioxide
then used by plants
water
Make ATP! Make ATP! All I do all day… And no one even notices!
food
ATP
enzymes
CO2
H2O O2

9. Mitochondria are everywhere!!
animal cells
plant cells

10. Using ATP to do work? Can’t store ATP ATP too unstable
only used in cell that produces it
only short term energy storage
carbohydrates & fats are long term energy storage
Adenosine TriPhosphate
work
Adenosine DiPhosphate
ADP
A working muscle recycles over 10 million ATPs per second

11. In your science notebook….
Reflect on:
Why must cells continuously make ATP?

12. { { { ATP A Body’s Energy Budget make energy eat food synthesis1
make energy
• energy needed even at rest
• activity
• temperature control {
ATP
eat food
• growth
• reproduction
• repair { 2
synthesis
(building)
• glycogen (animal starch)
• fat { 3
storage

13. Label the diagram
Glycolysis involves the breaking down of glucose molecules from carbohydrates into molecules of pyruvate, which will continue on to the Krebs Cycle. This process occurs in the cytosol of the cell and can proceed regardless of the presence of oxygen The reactions of glycolysis produces a net gain of 2 ATP molecules, as well as a release of 2 water molecules and 2 NADH molecules (these are another type of energy-rich molecule) As pyruvate is being shuttled from the cytosol to the interior of the mitochondrion, a microenzyme removes one carbon and two oxygens from each molecule, producing Aceytl CoA. This two-carbon sugar that actually enters the Krebs Cycle. The Krebs Cycle is a series of steps, catalyzed by enzymes, which completely oxidize the Aceytl CoA molecule. The Krebs Cycle is an aerobic process, meaning it needs oxygen to function. Two complete turns of the Krebs Cycle must occur to produce: 4 carbon dioxide molecules, 6 NADH molecules, 2 ATP molecules and 2 FADH2 molecules (yet another energy-yielding molecule). Most of the energy locked in the original glucose molecule will be released by the electron transport chain and oxidative phosphorylation. The electron transport chain is a network of electron-carrying proteins located in the inner membrane of the mitochondrion. These proteins transfer electrons from one to another, down the chain, much in the way a bucket brigade passes buckets of water. These electrons will eventually be added, along with protons, to oxygen, which is the final electron acceptor. This produces water, but does not produce any ATP. The ATP is actually produced by a proton motive force. This force is a store of potential energy created by the gradient formed when hydrogens (protons) are moved across a biological membrane. Therefore, the electron transport chain merely produces a gradient through which ATP can be made (this is known as chemiosmosis). The electron transport chain produces the remaining ATP.

14. Where does cellular respiration take place?
Glycolysis occurs in the cytoplasm, while the Krebs cycle and the ETC occurs in the mitochondria

15. Steps of Cellular Respiration

16. One more way to look at it….

17. What if oxygen is missing?
No oxygen available = can’t complete aerobic respiration
Anaerobic respiration
also known as fermentation
alcohol fermentation
lactic acid fermentation
no oxygen or no mitochondria (bacteria)
can only make very little ATP
large animals cannot survive
yeast
bacteria

18. Anaerobic Respiration
Fermentation
alcohol fermentation
yeast
glucose  ATP + CO2+ alcohol
make beer, wine, bread
lactic acid fermentation
bacteria, animals
glucose  ATP + lactic acid
bacteria make yogurt
animals feel muscle fatigue

19. Why is it an adaptive advantage to a cell to be able to perform either fermentation or the krebs cycle?
The Krebs cycle provides a pathway for obtaining energy when oxygen is present-Aerobic respiration
Fermentation provides a pathway for obtaining energy when oxygen is not present-Anaerobic respiration
Krebs provides a pathway for obtaining energy when oxygen is present, Fermentation provides a pathway for obtaining energy when oxygen is not present

20. Prior to entering the krebs cycle, two molecules of ____are broken down to form _____
C6H12O6, pyruvate
C6H12O6, acetyl-CoA
pyruvate, acetyl-CoA
acetyl-CoA, C6H12O6
Two molecules of pyruvate are broken down to form acetyl-CoA

21. In what type of cell’s would you expect to find the most mitochondria?
Muscle cells

22. What role does oxygen play in cellular respiration and photosynthesis?
O2 serves as a reactant in
cellular respiration and as a
product in photosynthesis