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CELLULAR RESPIRATIONSTAGE 3: ELECTRON TRANSPORT CHAIN
Glycolysis
Citric Acid Cycle (Kreb’s Cycle)
Electron Transport Chain (ETC)
in matrix (fluid) of mitochondria
Cellular RespirationDuring cellular respiration, nutrients like glucose are oxidized to provide the cell with useful energy. This process occurs in 3 distinct stages:
During cellular respiration, nutrients like glucose are oxidized to provide the cell with useful energy. This process occurs in 3 distinct stages:
in cytoplasmanaerobic
aerobic
in inner membrane of mitochondria (cristae)aerobic
Electron Transport Chain (ETC)
Electron transport chain occurs on inner membrane (cristae)
Electron Transport Chain
inner membrane (cristae)
outer membrane
Mitochondrion (cross-section)
matrix
intermembrane space
Involves a series of membrane proteins (cytochromes)
cytochromes
NADH and FADH2 (produced during CAC) give up H+ ions and electrons to cytochromes
H+ ions accumulate in intermembrane spaceElectrons are transported through chain of cytochromes
Electron Transport Chain
matrix
intermembrane space
Gradients drive H+ ions through protein channel, providing energy to synthesize ATP
High concentration of H+ ions in intermembrane space creates concentration gradient and electrostatic gradient
matrix
intermembrane space
high [H+]
low [H+]
Electron Transport Chain
As electrons released by NADH and FADH2 move through ETC, each cytochrome is alternately reduced and then oxidized, until electrons combine with final electron acceptor, oxygen
high [H+]
low [H+]
intermembrane space
matrix
Electron Transport Chain
When electrons are accepted by O2, H+ ions are also picked up, resulting in formation of H2O
½O2 2H+ H2O+
high [H+]
low [H+]
intermembrane space
matrix
Electron Transport Chain
Aerobicglucose
Glycolysis
2 pyruvate
2 ATP2 NADH
Pyruvate Oxidation
2 acetyl CoA
Kreb’s Cycle
2 NADH2 CO2
6 NADH2 FADH2
2 ATP4 CO2
E.T.C.
6 ATPx3
x3
x2
6 ATP
18 ATP4 ATP
2 ATP
2 ATP38 ATP
6 Cx3
Lactic acid is toxic biproduct
2 ATP
In animals, this occurs through lactic acid fermentationFor glycolysis to continue, NAD+ must be replenished
glucose
Anaerobic
Glycolysis
2 pyruvate
2 NADH
2 lactic acid
2 NAD+ Lactic Acid Fermentation
Total production of 2 ATP per glucose molecule
2 ATP
In bacteria and yeast, this occurs through alcohol fermentation
glucose
Anaerobic
Glycolysis
2 pyruvate
2 NADH
2 ethanol
2 CO2
Alcohol Fermentation
Total production of 2 ATP per glucose molecule
2 acetaldehyde
2 NAD+
For glycolysis to continue, NAD+ must be replenished
