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Cellular Respiration
oxygen+ glucose carbon dioxide+ water +energy
6O2 + C6H12O6  6CO2 + 6H2O +ATP
Cellular Respiration
Since animals cannot create food they
eat plants, or they eat plant-eating
animals.
 Plants and animals get energy from
food by cellular respiration.
 Occurs in the mitochondria, of the cell.
 Oxygen is used to get the energy out of
sugar.
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Cellular Respiration
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How much energy is actually in food?
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1 gram of the sugar glucose, when burned in the
presence of oxygen, releases 3811 calories of heat
energy!!!!
What is a calorie?
The amount of energy needed to raise the temp of
one gram of water 1 degree Celsius.
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Cellular Respiration
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Cells, of course don’t burn glucose, instead they
gradually release energy from glucose and other
food compounds. Release of energy from
glucose occurs in 3 steps
The pathway begins with Glycolysis
Then Krebs Cycle
And then Electron Transport Chain
Glycolysis
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Occurs in the cytoplasm of the cell.
Glycolysis is the process in which one molecule
of glucose(6C) is broken in half, producing two
molecules of pyruvic acid(3C)
Requires 2 ATP molecules to get it started, but
produces 4 ATP molecules and 2 NADH
molecules in return
Glycolysis
The cell has a net gain of 2 ATP
Fermentation

When Oxygen is not present, glycolysis is
followed by a different pathway.
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Fermentation.
 Alcoholic Fermentation –
 Produces Ethyl Alcohol and Carbon
dioxide
 Bread, beer, and wine are produced
Fermentation
 Lactic
Acid Fermentation
 Produced
in your muscles during rapid exercise
when the body cannot supply enough oxygen to
the tissues. This is why muscles feel sore after
intense activity
 Produces Lactic Acid and NAD+
Fermentation
Without Oxygen = Anaerobic
Overview of Cellular Respiration
Glucose
Electrons carried in NADH
Pyruvic
acid
Electrons carried
in NADH and
FADH2
Glycolysis
Cytoplasm
Mitochondrion
Copyright Pearson Prentice Hall
Cellular Respiration
Krebs Cycle
Also
called the citric acid cycle
Occurs after glycolysis
Aerobic respiration (with oxygen)
Occurs in the mitochondria
During
the Krebs Cycle, pyruvic acid is
broken down into carbon dioxide, NADH,
ATP, and FADH2 in a series of energy
extracting reactions.
Krebs Cycle Steps:
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In the presence of oxygen, pyruvic acid produced
in glycolysis passes to the 2nd stage of cellular
respiration.
During the Krebs cycle, pyruvic acid is broken
down into carbon dioxide in a series of energyextracting reactions.
Pyruvic Acid enters the mitochondrion, eventually
forming citric acid.
Citric acid is broken down to form a 4-carbon
molecule and carbon dioxide.
FADH2 and NADH are formed.
Figure 9-6 The Krebs Cycle
Chemical Pathways
Glucose
Glycolysis
Krebs
Cycle
Fermentation
(without 0xygen)
Electron
Transport
Alcohol or
lactic acid
Electron Transport Chain
Uses high-energy electrons from the Krebs cycle
to convert ADP into ATP. High-energy electrons
from NADH and FADH2 are passed into and along
the electron transport chain. As H is released to
form NAD and FAD, ATP is formed.
A TOTAL of 38 ATP are formed, but 2ATP are
used in Glycolysis leaving a net of 36 ATP.
Figure 9–7 Electron
Transport Chain
Mitochondrion
Electron Transport
Hydrogen Ion Movement
Channel
Intermembrane
Space
ATP synthase
Inner
Membrane
Matrix
ATP Production
Go to
Section:
Total energy
produced by
aerobic
respiration =
36 ATP
Comparing Photosynthesis and
Cellular Respiration
Photosynthesis
Function
Energy storage
Cellular
Respiration
Energy release
Location
Chloroplasts
Mitochondria
Reactants
CO2 and H2O
C6 H12O6 and O2
Products
C6H12O6 and O2
CO2 and H2O
Equation
6CO2 +6H2O -> Glucose
+ 6O2
6O2 + Glucose -> 6CO2 +
6H2O