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
O2
(carbohydrates)
aerobic respiration
making ATP energy (& some heat) by burning fuels
in many small steps
ATP
ATP + CO2 + H2O (+ heat)
food
(carbohydrates)
O2

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)

4. Where do we get energy?
• Energy is stored in organic molecules
• carbohydrates, fats, proteins
• Animals eat these organic molecules  food
• digest food to get
ATP
• fuels for energy (ATP)
• raw materials for building more molecules
• carbohydrates, fats, proteins, nucleic acids

5. ATP
What is energy
in biology?
Adenosine Triphosphate
Whoa!
HOT stuff!

6. Harvesting energy stored in food
• Cellular respiration
• breaking down food to produce ATP
• in mitochondria
• using oxygen = “aerobic” respiration
• usually digesting glucose
food
• but could be other sugars, fats, or
proteins O2
ATP
C6H12O6 6O2 6CO2
ATP
6H2O
Glucose Oxygen Carbon
Dioxide
Water
ATP

7. 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
• water
food
O2
Make ATP!
Make ATP!
All I do all day…
And no one
even notices!
ATP
enzymes
CO2 H2O

8. Mitochondria are everywhere!!
animal cells plant cells

9. Using ATP to do work?
Cannot store ATP
 too unstable
only used in cell that produces it
only short term energy storage
 carbohydrates & fats are long term energy storage
Adenosine TriPhosphate
A working muscle recycles over
10 million ATPs per second
Whoa!
Pass me the
glucose & oxygen!
ATP
ADP
work
Adenosine DiPhosphate

10. How organisms turn fuel into ATP
Fuel
(carbohydrates, lipids, proteins)
Anaerobic
Cellular Respiration
Oxygen present?
no yes
Alcoholic
Fermentation
Lactic Acid
Fermentation
Makes only a little
Aerobic
Cellular Respiration
ATP
Makes a LOT of
ATP ATP ATP
ATP
ATP
ATP
ATP
ATP
ATP
ATP ATP

11. Let’s first look at Aerobic Respiration

12. Aerobic Cellular Respiration
3 Major Steps:
1. Glycolysis
2. Kreb’s Cycle / Citric Acid Cycle
3. Electron Transport Chain

13. 1. Glycolysis
• Glyco = glucose lysis = splitting
• Where: in the cytoplasm
• Uses : glucose but NO oxygen
• Makes:
• Pyruvate (passed to Kreb’s Cycle)
• A little ATP
• NADH (electron bus… headed to the
Electron Transport Chain)

14. Glycolosis (no O2 required)
Glucose

G3P

2 Pyruvate

15. 2. Krebs Cycle
• Where?
• in the mitochondrial matrix
• Uses:
- pyruvate (from glycolysis)
• Makes:
• NADH (electron bus)
• FADH2 (electron bus)
• A little ATP (energy)
• Carbon Dioxide (waste product)

16. Krebs Cycle
• Two Acetyl CoA
enter cycle to
form Citric Acid
one at a time

17. 3. Electron Transport
• Where?
• Inner mitochondrial membrane
• Uses:
• NADH & FADH2
• Remember these are like “electron buses” that drop off
electrons to the ETC
• Oxygen
• Pulls electrons down the ETC and accepts them at the
end of the ETC
• This is why we die if we don’t get oxygen!
• Makes:
• Water (waste product)
• A BUNCH of A T P (whoohooo… big energy!)

18. How does the ETC make so much
energy ?
ATP
Answer = chemiosmosis
Sound familiar?
• We learned it in photosynthesis too!

19. Electron Transport
1. NADH & FADH2 drop off electrons
1. Oxygen pulls electrons down the ETC
2. Chemiosmosis = Hydrogen ions diffuse
from an area of high concentration
(outside the membrane) to an area of
low concentration (inner-membrane
space) through ATP synthase.
• Hydrogen ions then help to bond a
third phosphate group to ADP creating
lots of ATP

20. Electron Transport
1 2 3

21. Anaerobic Respiration
We know that aerobic cellular
respiration requires oxygen. But
what happens if there is no oxygen
available?
O2
Answer = Anaerobic Cellular Respiration

22. Anaerobic respiration
• The anaerobic pathway that
follows glycolysis
O2
• If there is no oxygen present and
an organism needs energy, the
cell may use anaerobic
respiration to continue producing
ATP

23. Anaerobic Respiration
• also known as fermentation
• alcohol fermentation
• lactic acid fermentation
• no oxygen or
no mitochondria (bacteria)
• makes very little ATP
• large animals cannot survive
using only fermentation
O2
yeast
bacteria

24. Anaerobic Respiration
• Fermentation
• alcohol fermentation
• yeast
O2
• glucose  ATP + CO2+ alcohol
• make beer, wine, bread
• lactic acid fermentation
• bacteria, animals
• glucose  ATP + lactic acid
• bacteria make yogurt
• animals feel muscle fatigue
Tastes good…
but not enough
energy for me!

25. Questions!
Number your paper 1 to 4

26. What is the overall purpose of cellular
respiration?
A. to make ATP
B. to produce H2O
C. to store glucose
D. to deliver oxygen

27. Which represents the general sequence of
cellular respiration?
A. TCA cycle chemiosmosis glycolysis
B. glycolysis Krebs cycle electron transport
C. electron absorption catalysis
phosphorylation
D. aerobic pathway anaerobic pathway
fermentation

28. Which stage of cellular respiration is the
anaerobic process?
A. glycolysis
B. Krebs cycle
C. electron transport

29. Which molecule generated by the Krebs
cycle is a waste product?
A. CoA
B. CO2
C. FADH2
D. NADH

30. Answers
1. A
2. B
3. A
4. B