Overview of Cell Respiration
• What is cell respiration?
– Process that converts sugar into ATP using oxygen
– Aerobic- requires oxygen
– Takes place in the mitochondria
– Like a mirror image of photosynthesis
Glycolysis
• Takes place in 3 stages
– Glycolysis, Krebs Cycle, and Electron transport chain
• Glycolysis must take place first
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Anaerobic- does not require oxygen
Takes place in cytoplasm
Splits glucose into two three carbon molecules- pyruvic acid
2 molecules of pyruvic acid, 2 molecules of ATP, and 2 molecules
of NADH are produced
Krebs Cycle
• Krebs cycle- transfers
energy to an electron
transport chain
– Breaks down three-carbon
molecules from glycolysis
– Makes a small amount of
ATP
– Releases carbon dioxide
– Energy output from one
molecule of pyruvic acid= 4
NADH, 1 FADH₂, and 1
molecule of ATP
– Transfers energy-carrying
molecules
Electron Transport Chain
• Electron transport chainproduces a large amount
of ATP
– Energy transferred to
electron transport chain
– 8 NADH and 2 FADH ₂ from
Kreb’s cycle
• Each NADH produces 3
molecules of ATP
• Each FADH ₂ produces 2
molecules of ATP
– Oxygen enters process
– ATP produced
– Water released as a waste
product
Totals
• Glycolysis- 2 ATP and 2 NADH
– 2 NADH produces 4 ATP
• Krebs Cycle- 2 ATP, 8 NADH, and 2 FADH ₂
• Electron Transport Chain- uses NADH and
FADH ₂ to produce ATP
– NADH produces 24 ATP
– FADH ₂ produces 4 ATP
• Total ATP molecules formed during cellular
respiration= 36
Overview of Cell Respiration
• Overall equation• Reactants in photosynthesis are same as the products
of cell respiration
Ch 9- Cellular Respiration
• Equation for cellular respiration
– 6 O₂+ C₆H₁₂O₆→ 6 CO₂+ 6 H₂O + Energy
• Photosynthesis?
– 6 CO₂+ 6 H₂O + Energy→6 O₂+ C₆H₁₂O₆
• Occurs in 3 stages
– Glycolysis- anaerobic, takes place in cytoplasm, products
enter mitochondria
– Kreb’s Cycle- aerobic (requires oxygen), occurs in
mitochondria
• Citric Acid Cycle
– Electron transport chain- aerobic, occurs in mitochondria
Main Stages of Cell respiration
• Glycolysis needs 2 ATP molecules to begin
process
• What happens during glycolysis?
– 2 molecules of pyruvic acid, 2 molecules of ATP, and 2
molecules of NADH are produced
• Kreb’s Cycle- Citric Acid Cycle
– During cycle, pyruvic acid is broken down into carbon
dioxide in a series of energy extracting reactions
– Energy output from one molecule of pyruvic acid= 4
NADH, 1 FADH₂, and 1 molecule of ATP
• NADH, FADH ₂ are high energy electron carriers
Main Stages cont.
• Electron transport chain- takes place in
mitochondria
– Uses high energy electrons from Krebs cycle to
convert ADP to ATP
– 8 NADH and 2 FADH ₂ from Kreb’s cycle
• Each NADH produces 3 molecules of ATP
• Each FADH ₂ produces 2 molecules of ATP
– Oxygen serves as last electron acceptor, and water
is last product made