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CO2 + H2O
Photosynthesis (plants, algae, cyanobacteria)
C6H12O6 + O2
Cellular Respiration(Eukaryotic cells)
CO2 + H2O
Cellular Respiration (requires O2 and gives off CO2)
Breakdown of glucose in the presence of oxygen to yield large amounts of ATP
Occurs in the cytoplasm and mitochondria of eukaryotic cellsC6H12O6 + 6O2 6CO2 + 6H2O + (36 ATP) (what is oxidixed?
reduced?)Exergonic reaction- high energy molecule, glucose, produces
low energy molecules; 39% efficientWhat do cells do with the ATP?
Cellular Respiration Occurs in 4 PhasesStage I: Glycolysis
(cytoplasm)Stage II: Prep
Stage (mitochondrial matrix)
Stage III: Citric Acid Cycle (mitochondrial matrix)
Stage IV: Electron Transport Chain oxidation- reduction reactions using NADH, FADH2
(mitochondrial cristae)
Stage I: GlycolysisAncient universal reactionBreakdown of glucose 2
pyruvatesOccurs in the cytoplasm;
outside of mitochondriaAnaerobicRequires an initial energy
(2 ATPs) investment4 ATPs are made by
substrate level phosphorylation (ATP synthesis)
Net Yield: 2 ATPs, 2 NADHs Substrate level
ATP synthesis; coupled reactions
NAD+ = redox coenzyme, carries electrons to ETC when O2 is available and is reused.
Substrate level ATP synthesis
Substrate level ATP synthesis
When O2 is not available fermentation occurs, with a net yield of 2 more ATP
Stage II: Prep Stage
Pyruvate Acetyl CoA
Occurs in the mitochondria (matrix)
Releases 2 CO2
Makes 2 NADH
Stage III: Citric Acid Cycle
A circular enzyme driven metabolic pathway that generates coenzymes and ATP
Occurs in the mitochondria (matrix)
Starts with the combination of oxaloacetate + Acetyl CoA citrate
2 turns = 2 ATPs, 6 NADH, 2 FADH2 are made
4 CO2 are released; Glucose has been converted to 6 CO2- 2 in prep, 4 in Citric acid cycle
Substrate level ATP synthesis
Stage IV: Electron Transport Chain (ETC)Movement of electrons
through a series of coenzyme/protein redox reactions to yield large amounts of ATP; electrons fall from hydrogen to oxygen releasing energy
Electrons (e-) are donated from NADH, FADH2 to the ETP
As, e- move through the ETP, they attract H+ ions to the outer compartment of mitochondria
Stage IV: ETC and Chemiosmosis
A electrical and H+ concentration gradient is created (10x)
H+ ions must move back from a higher lower concentration
Only return to inner compartment through ATP synthases, “gates of the dam”
As they move through, activate ATP synthase to make ATP from ADP + Pi
This process is called Chemiosmosis (ATP production linked to H+ gradient)
1 minute reserve of ATP
Stage IV-ETCThe coenzymes NADH and FADH2 give
up electrons to the ETPThe higher up in the ETP, the more
energy released by those e-1 NADH = 3 ATP, 1 FADH2 = 2 ATPThe final electron acceptor is O2, which
combines with H+ ions to form H2O How many ATPs are made through the
ETC?
Total ATP Yield during Cellular Respiration: Molecular Bookkeeping
Glycolysis: 2 NADH, 2 ATP
Prep stage: 2 NADH Citric Acid Cycle: 6
NADH, 2 FADH2, 2 ATP ETC: 34 ATP (but,
substract 2 ATP from total to account for NADH brought in from cytoplasm) = 32 ATP net
ATP yield from the complete breakdown of 1 glucose = 36 ATP
38 ATP in liver, heart, kidney cells
Anaerobic Respiration: A Comparison to Aerobic Respiration
Anaerobic respirationBreakdown of glucoseNo oxygen requiredLow ATP yieldQuick energy yieldStarts and finishes in
cytoplasmBacteria, muscle, yeast
cells
Cellular respirationBreakdown of glucoseOxygen requiredHigh ATP yield Slow energy yieldStarts in cytoplasmFinishes in
mitochondriaAnimal, plant cells
Anaerobic Respiration: Lactic Acid Fermentation
Pyruvate lactate + 2 ATP
Occurs in absence of O2
Lactobacillus (dairy products) and muscle cells
Quick, low energy yieldWastes glucose,
pyruvate cannot enter into Citric Acid Cycle
Anaerobic Respiration: Alcoholic Fermentation
Pyruvate ethanol + CO2
Occurs in absence of O2
Low ATP yield, wastes pyruvate (glucose)
Yeast cells (baking) and production of beer and wine
Metabolic Pool Concept
Human diet consists of other macromolecules such as proteins and fats. What happens to them?
Which of the biomolecules gives the cell the most ATP when completely broken down?
How much ATP would be made from a 18 carbon fatty acid? 9 Acetyl CoA?
Catabolism degradationAnabolism synthesis