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

Compare and Contrast Photosynthesis to Cellular Respiration