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CHAPTER 4
Cellular Respiration:
Harvesting Chemical Energy
The Big Picture
EQUATION FOR PHOTOSYNTHESIS
6CO2
+
Carbon Dioxide
6H2O + LIGHT
Water
C6H12O6
Glucose
+ 6O2
Oxygen
EQUATION FOR RESPIRATION
C6H12O6
Glucose
+
6O2
Oxygen
6CO2
+
Carbon Dioxide
6H2O
Water
+ ENERGY
ATP
Metabolism
The sum of all the chemical processes
occurring in an organism at one time
Management of material and energy
resources within the cell
Catabolic
– break down big molecules into
smaller ones
Anabolic
– build larger molecules from smaller
components
The Big Picture
Important points to remember:

Energy enters the food chain
through autotrophs

Heterotrophs must take in
energy from organic sources

Carbohydrates, proteins, and
fats do not come to us the way
our cells can use them.

So…how do organisms change
the food into energy to fuel
their bodies?
Cellular Respiration
How do we get from THIS
To THIS
ATP
• Energy molecule used
to shuttle energy
between catabolic and
anabolic reactions
• Energy is released from
ATP through the loss of
phosphate groups
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What is Cellular Respiration?
Cellular Respiration = making ATP through the
breakdown of foods
• Aerobic Cellular Respiration
• Fermentation
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Where Does Cellular
Respiration Take Place?
• Glycolysis and
Anaerobic Respiration
occurs in the
Cytoplasm of the cell
• Aerobic Respiration
takes place in the
Mitochondria
Overview of Cellular Respiration
Glucose
Glycolysis
All of the reactions involved in cellular
respiration can be grouped into these
stages:
Pyruvic Acid
Oxygen
Aerobic
Krebs Cycle
ETS
No Oxygen
Anaerobic
Fermentation
• Lactic Acid
• Alcohol
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
Three Stages of
Aerobic Cellular Respiration
C6H1206 + 6O26CO2 +6H20 + ENERGY

•

•

•
Glycolysis
in cytoplasm
Kreb’s cycle
in mitochondrial matrix
Electron Transport Chain
at inner membrane of
mitochondria
Glycolysis
• This part of cellular respiration
takes place in the cell
cytoplasm
• Each Glucose molecule gets
converted into 2 pyruvate
molecules
• Energy requiring and energy
releasing steps
• Energy net yield is 2 ATP and 2
NADH
• Enzymes help along the way
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
Krebs Cycle
• Each pyruvate
(carbohydrate)
molecule is
completely oxidized
into carbon dioxide
• Energy released from
these reactions results
in the formation of 1
ATP molecule and 3
NADH molecules
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
Collectively, 2 ATP and 6 NADH
are made from the 2 pyruvates.
NADH will be used in the electron
transport chain.
Electron Transport Chain
• The loss of electrons from
NADH result in the
addition of energy to
protein pumps in the
membrane
• H+ is moved from the
inside to the outside of
the inner membrane
• A gradient of H+ is created
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
What Carries the Electrons?
•
NAD+ (nicotinadenine
di-nucleotide) acts as
the energy carrier
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
•
NAD+ is a coenzyme
•
It is reduced to NADH
when it picks up two
electrons and one
hydrogen ion
Electron Transport Chain
• ATP is made as H+ ions
diffuse back into the
matrix of the mitochondria
by a different protein (ATP
synthase).
• The energy released by the
“rush” of H+ is used by this
enzyme to make ATP (kind
of like a rush of water in a
stream being used to turn
a water wheel).
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
A Little Krebs Cycle History
• Discovered by Hans
Krebs in 1937.
• He received the Nobel
Prize in physiology
medicine in 1953 for
his discovery.
• Forced to leave
Germany prior to WWII
because he was
Jewish.
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
Why do we need Oxygen?
• Oxygen is required by any organism that has mitochondria
because it is used to keep the Electron Transport Chain
running
• Oxygen pulls electrons from the chain and combines with
2 H+ to form H20
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
Electron Transport Chain Animation
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
Structure of the Mitochondria
• Organelle with an outer
This organelle produces the
and inner membrane
• The Krebs cycle takes
place in the matrix of
the mitochondria
– space bordered by the
inner membrane
• Electron Transport
Chain takes place across
the inner membrane
– between the matrix and
intermembrane space
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
majority of ATP for the cell.
Ultimately,
aerobic
respiration
produces about
36 ATP
molecules
from each
glucose
molecule.
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
Adding Up the ATP from Cellular Respiration
Cytosol
Mitochondrion
Glycolysis
Glucose
2
Pyruvic
acid
2
AcetylCoA
Krebs
Cycle
Electron
Transport
Maximum
per
glucose:
by direct
synthesis
by
direct
synthesis
by
ATP
synthase
Figure 6.14
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
Energy
yield from
complete
oxidation of
glucose by
aerobic
respiration
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
THE END
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings