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Cellular Energy
Cellular Respiration
Cellular Energy
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Energy (from breaking down food) is trapped
temporarily in ATP
Oxygen makes production of ATP more efficient
•
Aerobic (aero = with air) reaction
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ATP is produced in the presence of oxygen
Sometimes ATP can be produced without oxygen
•
Anaerobic (an = not or non, aero = with air) reaction
• ATP is produced WITHOUT the presence of oxygen
Cellular Respiration
The two stages of cellular
C6H12O6 + 6O2
respiration are:
1. Glycolysis- Glucose (simple
sugar) is broken down into
2 pyruvates and small
amount ATP and NADH
2. Kreb’s Cycle- Pyruvate &
NADH are used to make
more ATP. Electrons are
donated to make an even
more ATP
6CO2+ 6H20 + 38ATP
Glycolysis – Breaking Down
Glucose
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Glycolysis [glyco=carbohydrate (sugar), lysis=to break)
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1st stage of cellular respiration
Anaerobic process
Enzymes in mouths and stomachs break
large carbohydrates (ex. Starch) into
glucose
Glucose is used in the cytoplasm to fuel
Glycolysis
Glycolysis
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Occurs in the cytoplasm of cells
• Glucose is converted into
pyruvate producing a small
amount of ATP.
• (Remember glucose is an
energy source.)
• If there is not enough glucose
for glycolysis, then lipids can
be used. (ex. fats = energy
storage)
• This is what happens
when we diet.
Cellular Respiration Under
Aerobic Conditions
Aerobic Respiration
Krebs Cycle:
 Occurs in mitochondria
 -Pyruvate produced by
glycolysis enters a
mitochondria & gets
converted to AcetylCoA
 -Acetyl-CoA starts
Krebs cycle to
produce ATP & NADH.
Cellular Respiration Under
Anaerobic Conditions
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If oxygen is not available for
respiration, fermentation occurs
• Fermentation- recycling of energy (as NAD+)
without the presence of oxygen
• Krebs cycle can’t happen
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Two types of Fermentation:
• Lactic Acid
• Alcohol
Fermentation: Lactic Acid
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Lactic Acid Fermentation
• During glycolysis pyruvate is
converted to Lactic Acid
instead of Acetyl-CoA
• This lactic acid can build up
in muscle cells causing
muscle soreness
Fermentation: Alcohol
Fermentation
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Alcoholic Fermentation
• During glycolysis pyruvate is
converted to ethanol (alcohol)
• Yeast releases ethanol and carbon
dioxide as waste during fermentation
• The carbon dioxide causes bread to
rise and carbonation of beer
• Ethanol causes the intoxicating
effects of alcoholic beverages.
Electron Transport Chain:
Review
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During AEROBIC respiration energy donated by
the Krebs cycle fuels the electron transport
chain (ETC)
For a small amount of energy put into the chain,
the ETC produces a massive amount of ATP.
Cellular Respiration Wrap-Up
Photosynthesis vs. Respiration
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The products for photosynthesis are the materials for
cellular respiration and visa versa
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Photosynthesis starts of with carbon dioxide, water and
energy and ends with the production of sugar and water
Cellular respiration starts of with sugar and oxygen and
ends with the production of carbon dioxide, water and
energy.
Energy
Is stored
Is Harvested
Photosynthesis
Light Capture
Calvin Cycle
Respiration
ETC
Glycolysis
Krebs Cycle
ETC
Fermentation