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Photosynthesis and Cellular Respiration
CH7: Cellular Respiration pg 131
Section 3
Photosynthesis and Cellular Respiration
Section 3
Cellular Respiration
• All living organisms go through cellular
respiration.
– Series of chemical reactions to make ATP from glucose
Equation for Photosynthesis
• 6CO2 + 6H2O + pigment + sunlight C6H12O6 + 6O2
Equation for Cellular Respiration
• C6H12O6 + O2 6 CO2 + 6H2O + ENERGY (ATP)
Photosynthesis and Cellular Respiration
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• There are 2 scenarios
– Aerobic (with oxygen)
– Anaerobic (without oxygen)
• Anaerobic
– Glycolysis (only method for some prokaryotes)
• Occurs in cytoplasm
• Fermentation allows for this process to keep going
• 2 ATPs are made
Photosynthesis and Cellular Respiration
Aerobic Respiration
• Occurs in the mitochondria
• Kreb’s cycle
• Electron Transport Chain
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Photosynthesis and Cellular Respiration
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Glycolysis
• Series of chemical reactions that take place in the
cytoplasm and does not need oxygen to work.
• In glycolysis, enzymes break down one of glucose into
two pyruvate/pyruvic acid molecules.
*Glue glycolysis illustration into notes
Photosynthesis and Cellular Respiration
Glycolysis
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Photosynthesis and Cellular Respiration
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Glycolysis, pg 133
• Step 1, Breaking Down Glucose
– Glucose is converted back into 2 - G3P (3 carbon
molecule).
Photosynthesis and Cellular Respiration
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Glycolysis
• Step 2 and Step 3, NADH and Pyruvate
– Each of the G3P go through a series of chemical
reactions
• Converted into Pyruvate (pyruvic acid)
– 2 molecules NADH are created
• Important because NADH are Hydrogen ion/proton and
e- carriers
Photosynthesis and Cellular Respiration
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Glycolysis
Glycolysis produces 2 ATP
• with O2 it also produces 2 NADH, 2 Pyruvates
Photosynthesis and Cellular Respiration
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Fermentation (anaerobic process) pg 134
• To make ATP during glycolysis, NAD+ is converted to
NADH.
– Organisms must recycle NAD+ to continue making ATP through
glycolysis.
• The process in which carbohydrates are broken down in
the absence of oxygen is called fermentation.
– Beneficial because it allows glycolysis to continue supplying a
cell with ATP in anaerobic conditions.
Photosynthesis and Cellular Respiration
Pathway
Lactic Acid
Fermentation
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Reaction
PYRUVIC ACID + NADH LACTIC ACID + NAD+
*occurs in muscle cells for short term energy
production, also used in the
production of foods ex. yogurt, Kim chi, sauerkraut
Alcoholic
Fermentation
PYRUVIC ACID + NADH  ALCOHOL+ CO2 + NAD+
*occurs in yeast cells and is used in the production
of beer, wine and
bread
Photosynthesis and Cellular Respiration
Two Types of Fermentation
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Photosynthesis and Cellular Respiration
Cellular Respiration illustration
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Photosynthesis and Cellular Respiration
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Aerobic Respiration
• 1st stage is the Krebs cycle
– a series of reactions that produce electron carriers
• (NADH and FADH2)
• 2nd stage electron transport chain takes place in the
inner membranes of mitochondria
– ATP synthase are located here
• Up to 36 ATP molecules can be produced from one
glucose molecule in aerobic respiration.
Photosynthesis and Cellular Respiration
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Kreb’s Cycle
• Pyruvate (from glycolysis) is broken down and
combined with other carbon compounds creating CoA.
– Releasing CO2
– 2 ATP, 6 NADH, and 2 FADH2
Photosynthesis and Cellular Respiration
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Photosynthesis and Cellular Respiration
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Electron Transport Chain
• Takes place in the inner membranes of mitochondria
– ATP synthase are located here
• NADH and FADH2 from the Krebs cycle
– transfer energy in the form of e- and H+ into the electron
transport chain.
• e- are used to pump the H+ across the membrane to create a concentration
gradient
Photosynthesis and Cellular Respiration
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Electron Transport Chain
ATP Production
• Hydrogen ions diffuse through ATP synthase, providing
energy to produce several ATP molecules from ADP.
Photosynthesis and Cellular Respiration
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Photosynthesis and Cellular Respiration
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The Role of Oxygen
• At the end of ETC
– the e- combines with an oxygen atom and two hydrogen ions to
form two water molecules.
• If oxygen is not present,
– the electron transport chain stops, because hydrogen has no
where to go.
– the electron carriers are not recycled, so the Krebs cycle also
stops
Photosynthesis and Cellular Respiration
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Summary
Cellular
Respiration
Reactants
Products
Location
Gycolysis
Glucose, 2 ATP
2 Pyruvates,
2NADH,
4 (2) ATP
Cytoplasm
Krebs Cycle
2 AcetylCoA (CoA)
CO2, 6NADH,
2FADH2 ,2ATP
Matrix of
Mitochondria
ETC
6 NADH, 2FADH2,
O2
34 ATP, H2O,
6NAD, 2FAD
Inner
Mitochondrial
Membrane