1. An Overview of
Cellular
Respiration
Chapter 9
g
’s gettin
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chemica m
f ro
energy
is food!
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2. DO NOW
•
1.
2.
3.
Take out a piece of binder
paper & fold it into thirds
Top third – furthest place
you’ve ever traveled
Middle third – name of your
first pet
Bottom third – last person
you hugged
Ankara, Turkey
Tiger
Mitch

3. The Big Picture
• All cells require energy to do their work
• Cellular respiration produces this energy

4. What is cellular respiration?
• It is the main way that
chemical energy is
harvested from food
• Food molecules have
LOTS of energy – but that
energy can’t be used all
at once
• Food energy is stored as
ATP energy
Breathing
Muscle
cells
Cellular
respiration

5. Cellular respiration releases
energy
• Cellular respiration is catabolic and
exergonic
C6H12O6 + 6O2 --> 6CO2 + 6H2O + Energy (ATP and heat)
∆G = -686 kcal/mol of glucose broken down

6. • Catabolic
reactions are not
directly used to
power the cell
• The energy released is stored in molecules of
ATP
• ATP is then used to power the cell

7. Quick Think 1 – hug buddies
• Why don’t organisms use the
metabolic breakdown of food
directly to power the cell?
• In other words, why bother making
ATP?

8. General Information about
redox reactions
• Redox =
oxidationreduction
reactions
• Cellular respiration
is a series of redox
reactions

9. Many chemical reactions involve
the transfer of electrons from one
molecule to another
• These kinds of reactions
• The loss of
are called redox
electrons from a
reactions
substance =
oxidation
• The addition of
electrons to a
substance =
reduction

10. • The electron donor = reducing
agent (it reduced the other
substance)
• The electron acceptor = oxidizing
agent

11. Quick Think 2 – travel buddy
• In the following redox reaction, which
compound is oxidized and which is
reduced?
C4H6O5 + NAD+  C4H4O5 + NADH + H+

12. Oxygen is a powerful
oxidizing agent
• Oxygen is very electronegative
• The more electronegative an atom is, the
more energy it takes to pull away its
electrons

13. When electrons
move from a less
electronegative
atom to a more
electronegative
atom, it releases
energy
• A reaction that puts electrons closer
to oxygen releases energy

14. Respiration - the oxidation of
glucose by oxygen
• During cellular respiration, hydrogen and
its bonding electrons change partners
• Hydrogen and its electrons go from sugar
to oxygen, forming water
Oxidation
[Glucose loses electrons (and hydrogens)]
[Oxygen gains electrons (and hydrogens)]
Reduction

15. The Overall Equation for Cellular Respiration
Oxidation:
Glucose loses electrons
(and hydrogens)
Glucose
Carbon dioxide
Electrons
(and hydrogens)
Oxygen
Reduction:
Oxygen gains
electrons (and
hydrogens)
Energy

16. • Why does transferring
electrons to oxygen
release energy?
When electrons
move from glucose
to oxygen, it is as
though they were
falling
This “fall” of
electrons releases
energy during
cellular respiration
Release
of heat
energy

17. Glucose is a good fuel
• It has a lot of hydrogens
• Makes it a reservoir of
electrons
• Those electrons want to go to
a lower energy state by
moving toward the more
electronegative oxygen

18. Quick Think 3 – pet buddy
• Redox reactions involve ___________.
• Oxygen is very __________ so it is a
good _________.
• In cellular respiration, oxygen is used
to _________ glucose, thereby
releasing __________ due to the fall
of ___________ from glucose to ____.

19. • Enzymes help glucose get
oxidized in a series of
controlled steps
• So that the energy being
released is released in a
controlled, useful way

20. Overall redox
summary of cellular
respiration
• Cellular respiration = electrons in
glucose --> NADH --> electron
transport chain --> oxygen