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Cell Respiration Chap 9
Converting Food Into Cell
Energy (ATP)
1
Cell Energy Conversion
I.
What is energy?
A. The ability to do work.
II. How do we measure energy in
food?
A. A calorie is the amount of
energy needed to raise the
temperature of one gram of
water one degree.
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III.Cells store energy in chemical
bonds.
Blamo!!
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IV.Adenosine Triphosphate (ATP): Basic
energy source for all cells.
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V. How does ATP work?
Energy is stored by adding Phosphate
(P) to ADP & released by removing
(P) from ATP.
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VI. Functions of ATP
A. Chemical work–supplies energy
needed to make all the
macromolecules
B. Transport work–supplies energy to
transport substances across the cell
membrane. What do we call this?
C. Mechanical work–supplies energy
to allow muscle contraction,
separation of chromosomes etc.
D. ATP is used in almost every
function of the cell
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Cellular Respiration
I. Definition: The break down
of food for energy in the
form of ATP.
A. When oxygen is present we
call this aerobic respiration
B. If oxygen is absent we call
this anaerobic respiration.
C. Enzymes control every step of
this process.
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II. All living things use cellular
respiration to create cell energy.
III. Cellular respiration occurs in the
cytoplasm & the mitochondria.
IV. Overall chemical equation:
 6CO2 + 6H2O + 38 ATP
Glucose Oxygen Carbon Water energy
C6H12O6 + 6O2
dioxide
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Respiration is taking in
oxygen
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Who uses
cell
respiration?
Cellular
Respiration
occurs
in all living
things
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Cellular respiration takes
place in and around the
mitochondria in the
cytoplasm of the cell.
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Cell Respiration Pathways
I.
Food is broken down and
energy is released in a three
stage process.
A. Glycolysis
B. Kreb’s Cycle
C. Electron Transport
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Section 9-1
Mitochondrion
Electrons carried in NADH
Glucose
Pyruvic
acid
Glycolysis
Krebs
Cycle
Electrons
carried in
NADH and
FADH2
Electron
Transport
Chain
Mitochondrion
Cytoplasm
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Glycolysis
I. Glycolysis:
A. Glucose (6 Carbons) is broken in
half to form two pyruvate (3
Carbon) molecules.
B. Takes place in the cytoplasm of
a cell.
C. Doesn’t require oxygen.
D. Two ATP molecules are formed.
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Glycolysis (fig. 9-3)
Section 9-1
Glucose
Net Gain of two ATP!!
2 Pyruvic
acid
To the
electron
transport
chain
Greek word Glukus – sweet; Latin word
Lysis – to break
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Mitochondria: The cells power plant!!
Outer
Membrane
Inner
Membrane
Cristae
Matrix
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If oxygen is present, the two
three- carbon molecules pass into
the mitochondria through the
pores in the outer membrane.
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II. An intermediate step before Krebs Cycle
1. Pyruvate from the cytoplasm enters the
mitochondria.
2. A carbon is removed forming CO2 as waste.
3. High energy electrons are removed
changing NAD+ into NADH.
4. Coenzyme A joins the 2-carbon molecule
forming acetyle-CoA.
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The first step of the Krebs Cycle is for Acetyl
CoA to combine with a 4-carbon atom to form
the 6-carbon atom – Citric acid.
For this reason the Krebs Cycle is often
referred to as the Citric Acid Cycle
Krebs Cycle
I. Pyruvate is
broken down
into carbon
dioxide.
A. Takes place
in the matrix
of the
mitochondria.
B. Oxygen must
be present.
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Krebs Cycle
C. Each time a carbon
is removed energy
is generated. The
energy is captured
as NADH and
FADH2
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Krebs Cycle
D. The energy from
NADH is converted
into ATP through
an electron
Transport System
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Krebs Cycle
E. As carbons are
removed during the
Krebs Cycle they are
combined with
oxygen to form
carbon dioxide.
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Electron Transport Chain
I. The Electron transport chain uses
high energy electrons from the
Krebs cycle to convert ADP into
ATP.
A. The majority of the ATP
produced from breaking down
glucose is made by the ETC
embedded in the inner
membrane space.
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Section 9-2
Electron Transport
Hydrogen Ion Movement
Fig. 9-7
Channel
Intermembrane
Space
ATP
synthase
Inner
Membrane
Matrix
ATP Production
A. As electrons flow
B. Protons are pumped into the intermembrane space.
C. As the protons return back through ATP synthase,27
ATP is produced from ADP.
Electron Transport Chain
D. Oxygen is needed to pull
electrons through the ETC.
E. The ETC phase of respiration
produces 18 times more ATP
than Glycolysis alone.
F. For mitochondria to produce
the maximum amount of ATP
they must have oxygen and
pyruvic acid.
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The Totals – Cellular Respiration
• Glycolysis produces just 2 ATP
molecules per molecule of glucose.
• The complete breakdown of
glucose, including glycolysis,
results in the production of 36
molecules of ATP.
The Totals
Copyright Pearson Prentice Hall
Comparing Photosynthesis and Cellular
Respiration
• The energy flows in photosynthesis and
cellular respiration take place in opposite
directions.
Comparing Photosynthesis and
Cellular Respiration
• On a global level, photosynthesis and
cellular respiration are also opposites.
– Photosynthesis removes carbon dioxide
from the atmosphere and cellular
respiration puts it back.
– Photosynthesis releases oxygen into the
atmosphere and cellular respiration uses
that oxygen to release energy from food.
Aerobic Respiration
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Fermentation
I.Fermentation releases energy from
glucose under anaerobic (without
oxygen) conditions
A. 2 types of fermentation are:
1. Alcoholic fermentation
2. Lactic acid fermentation.
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Fermentation
II.Alcoholic fermentation.
Budding (asexual
reproduction)
Yeast cells
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A. Yeast uses alcoholic fermentation to
make alcohol (beer, wine) & make
bread rise (CO2 gas).
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III.Lactic acid fermentation –
Emergency energy system.
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A. Lactic acid is produced in your
muscles during rapid exercise
when O2 levels are low.
B. Lactic acid fermentation
converts glucose into lactic
acid.
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C. The buildup of lactic acid in
your muscles creates that
painful burning sensation.
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Lactic Acid Fermentation
• The first part of the equation is glycolysis
• The second part shows the conversion of
pyruvic acid to lactic acid.
Figure 9-4
Cell energy chemical pathways
Section 9-1
Most ATP created
Glucose
Glycolysis
Krebs
cycle
Fermentation
(without
oxygen)
Electron
transport
Alcohol or
lactic acid
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