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Cellular Respiration Part II:Glycolysis
Curriculum Framework
• f. Cellular respiration in eukaryotes involves a series of coordinated enzyme-catalyzed reactions that harvest free energy from simple carbohydrates.
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Big Energy Events of Respiration
– Glycolysis (breaks down glucose into two molecules of pyruvate)
– The citric acid cycle (completes the breakdown of glucose)
– Oxidative phosphorylation (accounts for most of the ATP synthesis)
Electronscarried
via NADH
Electrons carriedvia NADH and
FADH2
Citricacidcycle
Pyruvateoxidation
Acetyl CoA
Glycolysis
Glucose Pyruvate
CYTOSOL MITOCHONDRION
ATP ATP
Substrate-levelphosphorylation
Substrate-levelphosphorylation
Big Energy Events of Respiration
Electronscarried
via NADH
Electrons carriedvia NADH and
FADH2
Citricacidcycle
Pyruvateoxidation
Acetyl CoA
Glycolysis
Glucose Pyruvate
Oxidativephosphorylation:electron transport
andchemiosmosis
CYTOSOL MITOCHONDRION
ATP ATP ATP
Substrate-levelphosphorylation
Substrate-levelphosphorylation
Oxidative phosphorylation
Mitochondrion
Fuel (glucose)
Oxygen
Water
Carbondioxide
ATP
Curriculum Framework
GLYCOLYSIS2.F.1 Glycolysis rearranges the bonds in glucose molecules, releasing free energy to form ATP from ADP and inorganic phosphate, and resulting in the production of pyruvate.
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Glycolysis• Glycolysis is thought to be one of the oldest
metabolic pathways.• This energy harvesting process occurs in the
cytoplasm of both prokaryotic and eukaryotic cells.
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GlucoseATPMitochondrion
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Glycolysis
Glycolysis harvests chemical energy by oxidizing glucose to pyruvate
• Glycolysis (“splitting of sugar”) breaks down glucose into two molecules of pyruvate
• Glycolysis occurs in the cytoplasm and has two major phases
– Energy investment phase– Energy payoff phase
• Glycolysis occurs whether or not O2 is present
Electron carrier (NADH)
ATP Pyruvic acid
Glycolysis
• Activation energy input• Splitting the fructose• Harvesting the energy
–2 NADH + H+, 2 ATP–Two pyruvates (pyruvic acid)
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Substrate
Product
ADP
PATP
Enzyme Enzyme
Substrate-Level Phosphorylation
Inputs Outputs
GlucoseGlycolysis
2 Pyruvate 2 ATP 2 NADH
Curriculum Framework
2.F.2. Pyruvate is transported from the cytoplasm to the mitochondrion, where further oxidation occurs.
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What happens to the pyruvate?
Oxidation of Pyruvate to Acetyl CoA
• Before the citric acid cycle can begin, pyruvate must be converted to acetyl Coenzyme A (acetyl CoA), which links glycolysis to the citric acid cycle
• This step is carried out by a multienzyme complex that catalyzes three reactions
Pyruvic acidOuter mitochondrial membrane
Inner mitochondrial membrane
Carbon dioxide
Electron carrier (NADH)
Acetyl CoA
Pyruvate
Transport protein
CYTOSOL
MITOCHONDRION
CO2 Coenzyme A
NAD + HNADH Acetyl CoA
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2
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Figure 9.6-3
Electronscarried
via NADH
Electrons carriedvia NADH and
FADH2
Citricacidcycle
Pyruvateoxidation
Acetyl CoA
Glycolysis
Glucose Pyruvate
Oxidativephosphorylation:electron transport
andchemiosmosis
CYTOSOL MITOCHONDRION
ATP ATP ATP
Substrate-levelphosphorylation
Substrate-levelphosphorylation
Oxidative phosphorylation
Closing thoughts…
• What process is represented by A?
• What process is represented by B?
• C and D are products of A. What could they represent?
• What process is occurring at B?
• What does E represent?• What is the fate of E?
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Created by:
Debra RichardsCoordinator of Secondary Science ProgramsBryan ISDBryan, TX
