1. Chapter
9 Cellular
Respiration

2. • Feel the Burn
• Do you like to run, bike, or swim? These
all are good ways to exercise. When
you exercise, your body uses oxygen to
get energy from glucose,
a six-carbon sugar.
1. How does your body feel at the start of exercise, such as a long, slow
run? How do you feel 1 minute into the run; 10 minutes into the run?
2. What do you think is happening in your cells to cause the changes
in how you feel?
3. Think about running as fast as you can for 100 meters. Could you
keep up this pace for a much longer distance? Explain your answer.

3. 9-1 Chemical Pathways
• Food provides living things with
the chemical building blocks they
need to grow and reproduce
• Food serves as a source of raw
materials used to synthesize new
molecules
• Food serves as a source of
energy

5. calorie
• The amount of energy needed to
raise the temperature of 1 gram of
water 1 Celsius degree

6. Calorie
• 1000 calories

7. Chemical Pathways
Glucose
Glycolysis Krebs Electron
cycle transport
Fermentation Alcohol or
(without oxygen) lactic acid

8. Glycolysis
• First step in releasing energy from
glucose

9. Cellular Respiration
• The process that releases energy
by breaking down food molecules
in the presence of oxygen

10. The equation for cellular
respiration is…
O2 + C6H12O6 CO2 + H2O + ATP
Oxygen Glucose Carbon Water Energy
dioxide

12. Glycolysis
• The process in which one
molecule of glucose is broken in
half producing two molecules of
pyruvic acid
2 Pyruvic acid
Glucose
To the electron
transport chain

13. ATP Production
• You need to put a little energy in
to get going
• 2 molecules of ATP are used up
to get glycolysis going
• 4 molecules of ATP are produced
at the end of glycolysis
• Net gain of 2 ATP molecules

14. NADH Production
• One of the reactions of glycolysis
removes 4 high energy electrons
and passes them to a carrier called
NAD+
• NAD+ accepts a pair of high energy
electrons and becomes NADH
• NADH holds the electrons until they
can be transferred to other
molecules

15. NADH Production
• Energy yield from glycolysis is
small, but the process is fast
• Doesn’t require oxygen

17. Problems with glycolysis
• NAD+ molecules fill up with
electrons quickly
• Without NAD+ the cell cannot
keep glycolysis going and ATP
production stops

18. Chemical Pathways
Glucose
Glycolysis Krebs Electron
cycle transport
Fermentation Alcohol or
(without oxygen) lactic acid

19. Fermentation
• Releases energy from food in the
absence of oxygen

20. Fermentation
• During fermentation, cells convert
NADH to NAD+ by passing high
energy electrons back to pyruvic
acid
• Changes NADH back to NAD+
• Allows glycolysis to keep
producing ATP

21. Anerobic
• Does not require oxygen

22. There are 2 main types of
fermentation
1. Alcoholic Fermentation
2. Lactic Acid Fermentation

23. Alcoholic Fermentation
• Carried out by yeast
Pyruvic Acid + NADH alcohol + CO2 NAD+

24. Fermentation
Yeast

27. Lactic Acid Fermentation
• Regenerates NAD+ so that glycolysis
can continue
Pyruvic Acid + NADH lactic acid + NAD+
Glucose Pyruvic acid

28. Lactic Acid Fermentation
• Lactic acid is produced during
rapid exercise when the body is
low on O2
• You quickly run out of O2
• The buildup of lactic acid causes
painful burning sensation (This is
why you feel sore)

29. Lactic acid makes you sore
• Your body
creates an
oxygen debt
• You must
repay that
debt with
heavy
breathing
after the
exercise

30. Good Lactic Acid
• Unicellular organisms that produce lactic
acid during fermentation are used to make
• Cheese
• Yogurt
• Buttermilk
• Sour cream
• Pickles
• Sauerkraut
• Kimchi

31. Do Now
• Answer the questions on pg 6 of
your Chapter 5 packet.

32. 9-2 The Krebs Cycle and
Electron Transport
• At the end of glycolysis, about 90% of
the chemical energy that was
available in glucose is still unused,
locked in high energy electrons of
pyruvic acid
• To export the rest of that energy, the
cell turns to the worlds most powerful
electron acceptor… Oxygen

33. Aerobic
• Requires oxygen

34. • RESPIRATION • CELLULAR RESPIRATION
• Breathing • Energy releasing pathways

35. Glucose
Glycolysis Krebs Electron
cycle transport
Fermentation Alcohol or
(without oxygen) lactic acid

36. The Krebs Cycle
• Pyruvic Acid is broken down into
carbon dioxide in a series of
energy – extracting reaction

38. The Krebs Cycle
• CO2 released is the source of all
CO2 in your breath
• Makes ATP
• High energy electron carriers are
used to make huge amounts of
ATP

41. Glucose
Glycolysis Krebs Electron
cycle transport
Fermentation Alcohol or
(without oxygen) lactic acid

42. Electron Transport
• Uses the high – energy electrons
from the Krebs cycle to convert
ADP into ATP

44. A: Electron Transport
• High – energy electrons from NADH and
FADH2 are passed along the electron
transport chain
• At the end of the electron transport chain
is an enzyme that combines these
electrons with hydrogen ions and oxygen
to form water
• _____Oxygen_____serves as the final
electron acceptor of the electron transport
chain

45. B: Hydrogen Ion Movement
• Every time 2 high-energy electrons
transport down the electron transport
chain, their energy is used to transport
hydrogen ions (H+) across the membrane.
• During electron transport, H+ ions build up
in the intermembrane space, making it
positively charged.
• The other side of the membrane, from
which those H+ ions have been taken, is
now negatively charged.

46. C: ATP Production
• The inner membranes of the mitochondria
contain protein spheres called ATP synthases.
• As H+ ions escape through channels into these
proteins, the ATP synthases spin. Each time it
rotates, the enzyme grabs a low-energy ADP
and attaches a phosphate, forming high-energy
ATP.
• On average, each pair of high-energy electrons
that moves down the electron transport chain
provides enough energy to convert 3 ADP
molecules into 3 ATP molecules.

49. Cellular Respiration
ATP
Glucose +
(C6H1206) Carbon
Electron
Krebs Dioxide
+ Glycolysis Transport
Cycle (CO2)
Oxygen Chain
(02) +
Water
(H2O)

50. The Totals
• 18 times as much ATP can be
generated from glucose in the
presence of oxygen
• The final wastes of cellular
respiration are
– CO2
– H2O
• Q: How efficient is this?
• A: 38 percent of the total energy
of glucose is released.
– More efficient at using food than car
engines are at burning gasoline
• Q: What happens to the rest of
the energy?
• A: Given off as heat

51. Comparing Photosynthesis
and Cellular Respiration
• They are almost the opposite processes
• Savings account analogy
– Photosynthesis – “deposits energy”
– Respiration – “withdraws energy”
• Photosynthesis removes CO2, cellular
respiration puts it back
• Photosynthesis releases O2, cellular
respiration uses O2 to release energy