Cellular respiration involves three main stages - glycolysis, the Krebs cycle, and the electron transport chain. Glycolysis breaks down glucose and occurs in the cytoplasm, producing a small amount of ATP. The Krebs cycle and electron transport chain occur in the mitochondria and release more energy through the oxidation of pyruvate and other molecules, producing much more ATP through chemiosmosis. Together, these stages of cellular respiration fully break down glucose and other food molecules in the presence of oxygen to capture energy in the form of ATP.

1. What is Cellular Respiration?
A complex series
of metabolic
processes that
break down
carbohydrates
and release the
energy for use by
cells.
Obj: Describe the cellular
functions of photosynthesis and
respiration.

2. 9.1 Cellular Respiration: An Overview
• Food provides living things with the chemical
building blocks they need to grow &
reproduce
• For ALL organisms, food molecules contain
chemical energy that is released when
chemical bonds are broken!!

3. Chemical Energy & Food
• Organisms get the energy they need from food.
• Energy stored in food is expressed in units of
calories.

4. Chemical Energy & Food
• Food serves as a source of raw materials from
which cells can make new molecules (ATP=
energy)
• How much energy is in food?
– A calorie is the amount of energy needed to raise
the temperature of 1 gram of water 1 Celsius
degree
– A Calorie (used on food labels) is a kilocalorie or
1000 calories

5. Chemical Energy & Food
• Cells can use all sorts of food molecules
including fats, proteins, & carbohydrates.
• Example:
– 1 gram of glucose releases 3811 calories of heat
energy
– 1 gram of fat from beef releases 8893 calories of
heat energy
• SO- you get more energy per gram from
burning fats compared to burning glucose

6. Chemical Energy & Food
• Cells break down food gradually, capturing a
little bit of energy at key steps.
• This enables cells to use the energy stored in
the chemical bonds of foods like glucose to
produce compounds such as ATP that directly
power the activities of the cell.

7. What is the chemical equation
for cellular respiration?
• C6H12O6 + 6O2 → 6CO2 + 6H20 + 36 ATP
• Glucose + Oxygen → Carbon Dioxide + Water + ATP
• See 4 min video
Obj: Describe the cellular
functions of photosynthesis and

8. Overview of Cellular Respiration
In the presence of oxygen, glycolysis is followed
by the Krebs Cycle and electron transport chain
GLYCOLYSIS, KREBS CYCLE, & ETC make up
a process called cellular respiration or aerobic
respiration
Cellular respiration is the process that releases
energy by breaking down food molecules in the
presence of oxygen

9. ● Cytoplasm
•Mitochondria
•Mitochondria

10. Oxygen & Energy
• Oxygen is required at the very end of the
ETC
• Most of the energy-releasing pathways within
cells require oxygen, and that is the reason
we need to breathe (respire)
• Pathways that require oxygen as said to be
aerobic (Ex. Krebs Cycle & ETC)
• Pathways that do not require oxygen are
anaerobic (Ex. Glycolysis & Fermentation)

11. 2 Types of Cellular Respiration:
Requires Oxygen
Performed by
eukaryotic cells
Takes place in
Mitochondria
Efficient=
produces 36 ATP
Does NOT require Oxygen
Performed by
prokaryotic cells and
muscle cells
Takes place in the
cytoplasm
Inefficient= produces
2 ATP
Obj: Describe the cellular
functions of photosynthesis and

12. Comparing Photosynthesis &
Cellular Respiration
Photosynthesis
• Removes CO2 from the
atmosphere
• Releases O2 into the
atmosphere
• Only occurs in plants, algae,
& some bacteria
• Occurs in the chloroplasts
• Captures energy from
sunlight
Cellular Respiration
• Releases CO2 in the
atmosphere
• Removes O2 from the
atmosphere
• Occurs in plants, animals,
fungi, protists, and some
bacteria
• Occurs in the cytoplasm &
mitochondria
• Releases energy from food

13. The energy in photosynthesis and
respiration flows in opposite directions.
Cellular respiration is the process that
“withdraws” energy and photosynthesis is
the process the “deposits” energy.
The equations for photosynthesis and
respiration are the reverse of each other.

14. Energy Cycles
Photosynthesis and Cell Respiration Form a cycle.
Photosynthesis
6CO2 + 6H2O
Cell Respiration
C6H12O6 + 6O2 6CO2 + 6H2O + 36 ATP
Products of one reaction are the starting materials
of another.
See Big Picture animation
C6H12O6 + 6O2
Sunlight

15. ATP - Chemical Energy for Living Organisms
Plants
Plants, Animals, Fungi & some Bacteria

16. How are photosynthesis and
cellular respiration related??
Review video:
Practice Quiz
Obj: Describe the cellular
functions of photosynthesis and

17. Photosynthesis Cellular Respiration
Function Produces food for the
plant
Converts food into ATP
Location Chloroplast Cytoplasm &
Mitochondria
Reactants 6CO2 , 6H2O, sunlight C6H12O6 & 6O2
Products C6H12O6 & 6O2 6CO2 , 6H2O, 36 ATP
Chemical Equation 6CO2 + 6H20 + Sunlight
→C6H12O6 + 6O2
C6H12O6 + 6O2 → 6CO2
+ 6H20 + 36 ATP
Obj: Describe the cellular
functions of photosynthesis and

18. 9-2 The Process of Cellular
Respiration
•The process begins with a pathway called
glycolysis
•Glycolysis releases a small amount of
energy (ATP)
•Depending on the presence of oxygen,
glycolysis is followed by two different
pathways

19. 2 different pathways
•Glycolysis (anaerobic)
•If oxygen IS present
(aerobic), glycolysis is
followed by:
–Krebs Cycle
–Electron Transport
Chain
•Glycolysis (anaerobic)
•If oxygen is NOT
available, (anaerobic),
glycolysis is followed
by:
–Fermentation

20. See animation

21. Glycolysis
•Glycolysis takes place in the cytoplasm of
cells
•Glycolysis is an anaerobic process (no
oxygen present)
•Glycolysis is the process in which one
molecule of glucose is broken in half,
producing two molecules pyruvic acid

22. Glycolysis
•2 ATP are needed to start the process of
glycolysis
•When glycolysis is complete 4 ATP
molecules are produced
•This results in a NET GAIN of 2 ATP
molecules

23. Glycolysis
•NAD+ is an electron carrier
•Like NADP+ in photosynthesis, NAD+
accepts a pair of high energy electrons to
become NADH
•NADH can hold the energy of those
electrons and pass them on to different
pathways in the cell

25. In glycolysis, glucose is converted to pyruvate in the cytoplasm.
Glycolysis gives a small net gain of ATP without the use of oxygen.
Glycolysis is the splitting of glucose into pyruvate
http://highered.mheducation.com/sites/0072507470/student_vie
w0/chapter25/animation__how_glycolysis_works.html
Glycolysis Rap

26. Fermentation
•Fermentation releases energy from food
molecules in the absence of oxygen
–NADH produced in glycolysis transfers e- to
pyruvic acid. This allows NADH to recycle NAD+
needed to make ATP in glycolysis= steady supply
of ATP
–Anaerobic process – does not require oxygen
–Occurs in the cell’s cytoplasm
•2 types
–Lactic Acid (animal cells)
–Alcoholic (plants & fungi)

27. •c
•Pyruvate (3C) --> Ethanol (2C)
•CO2 removed
•EX. Yeast causes bread to rise,
making beer, wine, cheese
•Pyruvate --> Lactate
•If O2 available lactic acid can
convert back to pyruvate
•EX. Builds up in muscle cells
& causes soreness
2 Types of Fermentation

28. Anaerobic Respiration/
Fermentation
• Two Types of Fermentation:
• 1. Alcoholic Fermentation: When oxygen is
not present, fermentation follows glycolysis,
regenerating NAD+ needed for glycolysis to
continue.
• 2. Lactic Acid Fermentation: In lactic acid
fermentation, pyruvate is converted to lactate.
Obj: Describe the cellular
functions of photosynthesis and

29. Alcoholic Fermentation
• AFTER GLYCOLYSIS OCCURS- and No
oxygen is present some organisms go
through alcoholic fermentation (yeast,
bacteria and fungi)
• 2 Pyruvic acids are converted into 2
ATP’s, ethanol (alcohol) and Carbon
dioxide
• Process is used to
make beer, breads,
pastries etc. Obj: Describe the cellular
functions of photosynthesis and

30. Use of anaerobic cell respiration in yeasts to produce ethanol and carbon dioxide in baking.
Ethanol is also produced by anaerobic cell
respiration, but it evaporates during
baking.
Bread is made by adding water to flour, kneading the mixture to make
dough and then baking it. Usually an ingredient (yeast) is added to the
dough to create bubbles of gas, so that the baked bread has a lighter
texture.
After kneading (mixing) the dough is
kept warm to encourage the yeast to
respire.
Yeast can respire aerobically or anaerobically, but oxygen in the
dough is soon used up so the yeast is forced to respire
anaerobically.
The carbon dioxide produced by anaerobic cell respiration cannot
escape from the dough and forms bubbles causing the dough to
swell and rise.

31. http://en.wikipedia.org/wiki/File:Ethanol_plant.jpg
Bioethanol (ethanol produced by
organisms) is a renewable energy source.
Use of anaerobic cell respiration in yeasts to produce ethanol and carbon dioxide in baking.
Most bioethanol is produced from sugar
cane and maize, using yeast.
Fermenters are used to keep the yeast in optimum
conditions.
When yeast carry out anaerobic
respiration the sugars in the plant
material are converted to ethanol and
carbon dioxide.
Starch and cellulose in the plant material
are broken down by enzymes into sugars.
The ethanol produced by the yeasts
is purified by distillation and water
is removed to improve combustion.

32. Lactic Acid Fermentation
• AFTER GLYCOLYSIS OCCURS- and No
oxygen is present, lactic acid fermentation
may occur in your muscle cells.
• Once ATP & O2 reserves are exhausted
(oxygen debt), 2 ATP’s and lactic acid will be
produced= burn in muscles
• Labored breathing repays the oxygen debt
Obj: Describe the cellular
functions of photosynthesis and

33. Lactate production in humans when anaerobic respiration is used to maximize the power of muscle contractions.
Certain human activities require anaerobic
respiration such as weightlifting and sprinting.
Rapid generation of ATP enables us to
maximise the power of muscle
contractions.
Aerobic respiration generates a much greater yield
of ATP, but anaerobic respiration can supply ATP
very rapidly, as oxygen is not required.
Anaerobic cell respiration produces lactate. There is a
limit to the concentration that the body can tolerate and
this limits how much or how long anaerobic respiration can
be done for.
Afterwards lactate must be broken down. This involves the use
of oxygen. It can take several minutes for enough oxygen to be
absorbed for all lactate to be broken down. The demand for
oxygen that builds up during a period of anaerobic respiration is
called the oxygen debt.

34. Obj: Describe the cellular
functions of photosynthesis and

35. Obj: Describe the cellular
functions of photosynthesis and

36. Glycolysis
• Glucose is
broken down
to pyruvate or
pyruvic acid
during
glycolysis,
making a net
gain of 2 ATP
and 2 NADH.
• Review with
animation
Takes place in the Cytoplasm
Obj: Describe the cellular
functions of photosynthesis and

37. Step 2- What happens next?
If O2 is present
→ moves to
aerobic resp. in
mitochondrion.
If O2 is not
present→ moves
to anaerobic
resp.
Obj: Describe the cellular
functions of photosynthesis and

39. .
Label the structures of the mitochondria:

40. .
Label the structures:
matrix
Inter-membrane space
ribosomes inner membrane
outer membrane
naked loops of
DNA
cristae

42. Aerobic Respiration (3 Steps)
1. Glycolysis (Glucose to Pyruvate)
2. Krebs Cycle (Pyruvate to NADH, FADH2)
3. Electron Transport Chain w/ O2
(NADH, FADH2 to ATP)

43. Krebs Cycle
•During the Krebs Cycle, pyruvic acid is
broken down into carbon dioxide in a
series of energy-extracting reactions
•AKA= Citric Acid Cycle (starting material)
•Occurs in the matrix of the mitochondria
•Aerobic
•Every time you exhale, you release the
carbon dioxide produced by the Krebs
cycle

44. Intermediate Step - Breakdown
of Pyruvic acid
• Pyruvic acid is
broken down into
Acetyl coA and
CO2
Obj: Describe the cellular
functions of photosynthesis and

45. Step 2- Citric Acid/ Krebs Cycle
• Requires:
– Acetyl coA
– Oxygen
– Produces:
• CO2
• 2 ATP
• NADH
• FADH
-TAKES PLACE IN THE MATRIX OF THE MITOCHONDRIA
*Everytime you exhale, you release Carbon dioxide released
in the Kreb’s cycle!

46. Energy Extraction By Kreb’s Cycle
– Per glucose:
• 6 CO2 molecules,
• 2 ATP molecules,
• 8 NADH molecules,
• 2 FADH2 molecules
are produced.
Review with video from
Molecular and cellular
biology learning center

48. Krebs cycle reduces electron carriers in preparation for oxidative
phosphorylation (carbon is released as CO2 as a by-product)
http://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=swf::525::530::/sites/dl/free
/0072464631/291136/krebsCycle.swf::krebsCycle.swf

49. Step 3- Electron Transport Chain:
-FADH & NADH2 CARRY THE ELECTRONS DOWN THE CHAIN
- OXYGEN SERVES AS THE FINAL ELECTRON ACCEPTOR TO
PRODUCE WATER
-TAKES PLACE IN THE INNER MEMBRANE OF THE MITOCHONDRIA
IN EUKARYOTES
• Requires:
– Oxygen
– Electrons
– H ions
– Produces:
– 32 ATP
– H2O
Obj: Describe the cellular
functions of photosynthesis and

50. Electron Transport Chain
• Occurs in the cristae (inner folds) of the
mitochondria
• Aerobic
• Uses high-energy electrons from NADH
and FADH2 to convert ADP to ATP
• Oxygen serves as the final electron acceptor
in the ETC. It is essential for getting rid of
low-energy electrons & hydrogen ions

51. Electron Transport Chain

53. Electron Transport
– NADH and FADH2 pass their high-energy
electrons to electron carrier proteins in the
electron transport chain.

54. Electron Transport
– At the end of the electron transport chain, the
electrons combine with H+ ions and oxygen to
form water.

55. Electron Transport
– Energy generated by the electron transport
chain is used to move H+ ions against a
concentration gradient across the inner
mitochondrial membrane and into the
intermembrane space.

56. ATP Production
– H+ ions pass back across the mitochondrial
membrane through the ATP synthase, causing
the ATP synthase molecule to spin. With each
rotation, the ATP synthase attaches a phosphate
to ADP to produce ATP= Chemiosmosis

57. A summary of oxidative phosphorylation
http://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=s
wf::535::535::/sites/dl/free/0072437316/120071/bio11.swf::Elec
tron%20Transport%20System%20and%20ATP%20Synthesis
Use the animations to learn to check your
understanding of oxidative phosphorylation.

58. See animation

59. Energy Totals
• How much chemical energy does cellular
respiration yield from a single molecule of
glucose?
•In the absence of oxygen
(anaerobic)= 2 ATP
•In the presence of oxygen
(aerobic) = 36 ATP
–2 ATP from glycolysis
–2 ATP from Krebs
–32 ATP from ETC
This represents 36% of total energy in
glucose
•The remaining 64 percent is
released as heat.
•See BIG PICTURE animation

60. Summary of Cell Respiration
• Total Yield:
• 36 ATP
• 6 Molecules of Water
• 6 molecules of Carbon
dioxide
• Mr. Parr Song
• Cyanide video
• Cassava video
Obj: Describe the cellular
functions of photosynthesis and

62. Energy & Exercise
Quick Energy
•Cells contain a small
amount of ATP produced
during glycolysis- enough
for a few seconds of
intense activity
•After roughly 50 meters,
stored ATP is gone, at
that point muscles will
produce ATP through
lactic acid fermentation=
enough ATP for 90
seconds
Long- Term Energy
•For exercise longer than
90 seconds, cell
respiration is the only way
to generate a constant
supply of ATP
•Your body stores energy
as glycogen- this usually
lasts for 15-20 minutes of
activity
•After that your body starts
to break down other
stored molecules like fat-
beneficial for weight
control

63. Energy Totals
– The cell can generate ATP from just
about any source, even though we’ve
modeled it using only glucose. Complex
carbohydrates are broken down into simple
sugars like glucose. Lipids and proteins
can be broken down into molecules that
enter the Krebs cycle or glycolysis at one
of several places.

64. Energy from several sources:

65. Energy from several sources

66. Catabolic vs Anabolic Pathways

67. Energy Sources During
Exercise:
• First few seconds: ATP reserves in
muscle (creatine phosphate to charge up
ADP)
• Next 90 seconds: ATP produced by lactic
acid fermentation
• 90 seconds -15 to 20 minutes: glycogen
stored in muscle (converted to ATP)
• After 15- 20 minutes: fat reserves
(converted to ATP)
Obj: Describe the cellular
functions of photosynthesis and

68. Obj: Describe the cellular
functions of photosynthesis and

69. Obj: Describe the cellular
functions of photosynthesis and
2a. 2b. 3.
3

70. Obj: Describe the cellular
functions of photosynthesis and

71. Obj: Describe the cellular
functions of photosynthesis and

72. Obj: Describe the cellular
functions of photosynthesis and
2a 2b 3
3

73. Obj: Describe the cellular
functions of photosynthesis and
2a 2b. 3.
3

78. GLYCOLYSIS KREB CYCLE ELECTRON TRANSPORT
CHAIN
LOCATION:
AEROBIC or ANAEROBIC
SUMMARY:
LOCATION:
AEROBIC or ANAEROBIC
SUMMARY:
LOCATION:
AEROBIC or ANAEROBIC
SUMMARY:
INPUTS OUTPUTS INPUTS OUTPUTS INPUTS OUTPUTS
ENERGY GAINED ENERGY GAINED ENERGY GAINED

80. Obj: Describe the cellular
functions of photosynthesis and

81. Obj: Describe the cellular
functions of photosynthesis and

82. Mystery of 7 Deaths Case Study:
•1982 Chicago Area: 7 Die of unknown
cases
•Unknown suspect tampers with Tylenol
bottles and laces them with cyanide
•Johnson and Johnson company
immediately calls back product from
shelves and loses about $100 million
•Case still unsolved

83. 7 Deaths Cont’d
•Company reintroduced product with triple
seal tamper resistant packaging
•Offered $2.50 off coupon on purchase of
products to recoup lost revenue