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Cellular RespirationCellular Respiration
pp. 174-178
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Cellular Respiration
Cellular respiration is the process by which glucose (C6H12O6) is broken down to release energy for making ATP, another form of chemical energy.
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Cellular Respiration – Equation
C6H12O6 + 6 O2 6 H2O + 6 CO2 + 36 ATP
foodfood(glucose, a carbohydrate)(glucose, a carbohydrate)
oxygenoxygen waterwater carboncarbondioxidedioxide
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BioTheme: Interdependence!
Photosynthesis:
6 H2O + 6 CO2 + energy (sun) → C6H12O6 + 6 O2
Cellular Respiration:
C6H12O6 + 6 O2 → 6 H2O + 6 CO2 + energy (ATP))
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The BIG Question is…
Do only animals respire?
Or do plants respire too?
Only plants perform photosynthesis Plants AND animals perform cellular
respiration!
(Can you explain why??)
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Cellular Respiration Overview
Three Stages:1. Glycolysis (occurs in both aerobic and
anaerobic)
2. Krebs Cycle3. Electron Transport Chain
The Main form of Energy produced = ATP
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Significant ATP Production
Aerobic cellular respiration releases energy SLOWLY, using oxygen to convert ONE molecule of glucose to 36 ATP!
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GlucoseGlycolysis
Cytoplasm
Pyruvic acid
Electrons carried in NADH
Krebs Cycle
Electrons carried in
NADH and FADH2 Electron
Transport Chain
Mitochondrion
Cellular Respiration: An Overview
Mitochondrion
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Glycolysis
Glyco = Glucose lysis = Breakdown Occurs in the cytoplasm of the cell Molecules of GLUCOSE are broken
down into 2 molecules of Pyruvic Acid. Cell must use (invest) 2 ATP Products:– 2 pyruvic acid– 2 ATP– 2 NADH
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Glycolysis
GlucosePyruvic Acid
Pyruvic Acid
To the Electron Transport Chain
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Site of Cell Respiration The mitochondria is the
organelle where the final stages of cellular respiration occurs.– Krebs Cycle– Electron Transport
Chain
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Krebs Cycle
Aerobic Process = Only if oxygen is present Occurs in the MATRIX of the mitochondria Pyruvic Acid from Glycolysis enters to form– 2 ATP– 6 NADH– 2 FADH2
– CO2 (which is released when we exhale!!)
AKA Citric Acid Cycle
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Krebs Cycle
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Electron Transport Chain
Energy carrier molecules produced during Glycolysis and the Kreb’s Cycle enter the ETC
– NADH– FADH2
Occurs in the folds of the Inner Membrane of the Mitochondria (Cristae)
The electrons are passed down a chain of proteins until they reach the final electron acceptor…..oxygen!– So this step is aerobic (requires oxygen)
The ETC produces 32 ATP and H2O
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Cellular Respiration Flowchart
Glucose(C6H1206)
+Oxygen
(02)
GlycolysisKrebsCycle
ElectronTransport
Chain
Carbon Dioxide(CO2)
+Water(H2O)
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Cellular Respiration (anaerobic)
What happens when cells don’t have enough oxygen? Some organisms live in an oxygen-free environment.
How do they get their energy?The Kreb’s Cycle and Electron Transport
Chain can’t function!!
These are anaerobic conditions!!
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Minimal ATP Production
In the absence of oxygen, anaerobic respiration only releases 2 ATP for each molecule of glucose broken down.
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Cellular Respiration (anaerobic)
Anaerobic respiration is also called fermentation, or the process by which energy is released from glucose when oxygen is NOT available.
This process allows organisms to continue to produce energy until oxygen is available.
However, this process only releases 2 ATP per molecule of glucose.
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Fermentation
Releases less energy than aerobic respiration
Occurs in the Cytoplasm– just like glycolysis
Fermentation– A series of reactions that convert NADH
(from glycolysis) back into NAD allowing glycolysis to keep producing a small amount of ATP
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Alcoholic Fermentation
Anaerobic way of converting energy for yeast and other microorganisms
Glucose broken down to produce alcohol, CO2 and energy (ATP)
C6H12O6 + pyruvic acid ethanol + CO2 + 2 ATP
EX: baking bread with yeast (dough rises) fermenting wine & beer
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Lactic Acid Fermentation
Anaerobic way of converting energy in animal cells and some microorganisms
Glucose broken down to produce lactic acid, CO2 and energy (ATP)
C6H12O6 + pyruvic acid lactic acid + 2 ATP
EX: muscle cells during strenuous exercise fermenting cheese, yogurt, sour cream
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Lactic Acid Fermentation
– Occurs in bacteria (unicellular organisms)– This is how cheese, yogurt, and pickles are
made.
– Occurs in muscles during rapid exercise–When your body runs out of oxygen your muscle
cells must produce some ATP using fermentation and glycolysis
– Lactic Acid build-up causes muscle soreness or burning after intense activity.
Pyruvic Acid + NADH lactic acid + NAD+
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Strenuous Exercise
Lactic acid is produced by your muscle cells during rapid exercise when the body cannot supply enough O2 to tissues.
Without enough O2, the body is NOT able to produce all of the ATP that is required.
The buildup of lactic acid can cause painful burning in your muscles
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Fermentation Summary
Glycolysis: Glucose 2 Pyruvic Acid Fermentation: 2 Pyruvic Acid ? or ?
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Chemical Pathways
Glucose
Glycolysis Krebs cycle
Electrontransport
Fermentation (without oxygen)
Alcohol or Lactic Acid
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Comparing ATP Production
First, your body breaks down glucose through aerobic respiration to produce 36 ATP per glucose molecule; however, this is a slow process.
When muscle cells cannot get enough O2 they break down glucose through lactic acid fermentation to produce 2 ATP per glucose…
Therefore, AEROBIC RESPIRATION is much more efficient in terms of ATP production – 36 ATP compared to 2 ATP!
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Aerobic Training
Ex: long runs, biking, swimming
Can increase the size and number of mitochondria in muscle cells
Can increase the delivery of O2 to muscles by improving the heart and lungs
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Anaerobic Training
Ex: sprints, strides, quick bursts of energy
Increase the glycogen levels in the muscles
Increase body’s tolerance to lactic acid