Download Cellular Respiration

Energy and Life
 Living things need energy to survive
 comes from food
 energy in most food comes from the sun
 Plants use light energy from the sun to produce food
 autotrophs organisms that make their own food
Ex - plants
 heterotrophs organisms that must obtain energy from the foods they
consume
 animals

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9-1 Chemical Pathways
 Food serves as a source of raw materials for the cells in the body and as a
source of energy.
Animal Cells
Animal
Mitochondrion
Plant
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Plant Cells
Chemical Energy and ATP
 Energy – the ability to do work
 Forms: light, heat, electricity, chemical compounds
 chemical compound that cells use to store and release energy is
adenosine triphosphate (ATP)
 ATP - basic energy source for all cells
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Chemical Energy and ATP
 ATP consists of:

adenine

ribose (a 5-carbon sugar)

3 phosphate groups
Adenine
4
ATP
Ribose
The three phosphate
groups are the key to
ATP's ability to store
and release energy.
3 Phosphate groups
Chemical Energy and ATP
 Storing Energy
 ADP has two phosphate groups instead of three.
 A cell can store small amounts of energy by adding a phosphate group to ADP.
ATP
ADP
+
Adenosine Diphosphate
(ADP) + Phosphate
Partially
charged
battery
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Energy
Fully
charged
battery
Adenosine Triphosphate (ATP)
Chemical Energy and ATP
 Releasing Energy
 Energy stored in ATP is released by breaking the chemical bond between
the second and third phosphates.
2 Phosphate groups
P
ADP
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Chemical Energy and ATP
ATP energy uses:
- cellular activities: active transport, protein
synthesis
- muscle contraction
 Most cells have only a small amount of ATP, because it is
not a good way to store large amounts of energy.
 Cells can regenerate ATP from ADP as needed by using
the energy in foods like glucose.
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Cellular Respiration
 So what do our cells do with the Oxygen and why do they
give off Carbon Dioxide?
 Answer: To make ATP!
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Cellular Respiration
C6H12O6 + 6O2  6CO2 + 6H2O + usable energy
(ATP)
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Cellular Respiration (3-stages)
 Glycolysis
 Krebs Cycle (Citric Acid Cycle)
 Electron Transport Chain (ETC)
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Overview of Cellular Respiration
 If oxygen is present:
 cellular respiration - the process that releases energy by
breaking down glucose and other food molecules in the
presence of oxygen
 glycolysis  Krebs cycle  electron transport chain
 equation:
 6O2 + C6H12O6 → 6CO2 + 6H2O + Energy
 oxygen + glucose → carbon dioxide + water + Energy
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Flowchart
Section 9-2
Cellular Respiration
Glucose
(C6H1206)
+
Oxygen
(02)
Glycolysis
Krebs
Cycle
Electron
Transport
Chain
Carbon
Dioxide
(CO2)
+
Water
(H2O)
+
ATP
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Figure 9–3 Glycolysis
Glycolysis:
Step 1
Glucose
2 Pyruvic acid
To the electron
transport chain
Figure 9–3 Glycolysis
Section 9-1
Glucose
2 Pyruvic acid
To the electron
transport chain
Figure 9–3 Glycolysis
Section 9-1
Glucose
2 Pyruvic acid
To the electron
transport chain
 Where Cytoplasm
 NO O2 required
 Energy Yield net gain of
2 ATP at the expense of 2 ATP
 6-C glucose  TWO 3-C pyruvates
 Free e- and H+ combine with organic ion carriers called
NAD+  NADH + H+
(nicotinamide dinucleotide)
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Summary
 In
Glucose (6-C)
2 ATP
 Out
2 pyruvate; 2(3-C)
2NADH
a net of 2 ATP
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Breakdown of Pyruvic Acid
 Where mitochondria
 Pyruvate (3-C) 
Acetic acid (2-C)
 3rd C forms CO2
 Acetic acid combines
with Coenzyme A to
form ACETYL-CoA
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The Krebs Cycle
Section 9-2
Citric Acid
Production
Mitochondrion
Krebs Cycle
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Second Step: Citric Acid Cycle (Krebs
Cycle)
 Where Mitochondrial matrix
 Energy Yield 2 ATP and more e Acetyl-CoA (2-C) combines with 4-C to form 6-C
CITRIC ACID
 Citric Acid (6-C) changed to 5-C then to a 4-C
 Gives off a CO2 molecule
 NAD+ and FAD pick up the released e FAD becomes FADH2
 NAD+ becomes NADH + H+
 Cycle ALWAYS reforming a 4-C molecule
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ETC
 Where inner membrane of mitochondria
 Energy Yield Total of 32 ATP
 O2 combines with TWO H+ to form H2O
 Exhale - CO2, H2O comes from cellular respiration
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Electron Transport Chain
Section 9-2
Electron Transport
Hydrogen Ion Movement
Channel
Mitochondrion
Intermembrane
Space
ATP synthase
Inner
Membrane
Matrix
ATP Production
Summary
Mitochondrion
Electrons carried in NADH
Pyruvic
acid
Glucose
Glycolysis
Krebs
Cycle
Electrons
carried in
NADH and
FADH2
Electron
Transport
Chain
Mitochondrion
Cytoplasm
Aerobic vs. Anaerobic
 Anaerobic DOES  Aerobic requires oxygen
NOT require oxygen Yields large amounts of
 Fast, but produces
energy
smaller amounts of
energy (ATP)
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