anaerobic respiration. during the last stage of cell respiration, electrons from glucose are passed...
Post on 21-Dec-2015
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Anaerobic Respiration
During the last stage of cell respiration, electrons from glucose are passed
down the electron passport chain to the
final electron acceptor, oxygen
Chemiosmosis couples the electron transport
chain to ATP synthesis:
Aerobic Respiration
• When oxygen is the final electron acceptor, the process is called aerobic respiration
• Aerobic = occurring in the presence of oxygen
Anaerobic Respiration
• Some prokaryotes are able to carry out anaerobic respiration, respiration in which an inorganic molecule other than oxygen (O2) is the final electron acceptor.
• For example, some bacteria, called nitrate reducers, can transfer electrons to nitrate (NO3
-) reducing it to nitrite (NO2-).
• Less efficient: usually 30-34 ATPs per glucose molecule.
What happens if there is no available electron acceptor?
Glucose
2 pyruvate
2 ATP
2 ADP 2 NAD+
2 NADH
Aerobic respiration: The NADH then passes its high energy e- to the electron transport chain (becoming NAD+ again) and eventually to O2
Anaerobic respiration: Without O2, NADH has nowhere to donate its e- to, NAD+ cannot be regenerated, and glycolysis stops
glycolysis
Anaerobic fermentation
• Fermentation: An alternative set of reactions that can follow glycolysis in the absence of oxygen as a final electron acceptor.
• Extremely inefficient: no Kreb’s cycle, no ETC. Glycolysis produces a net of 2 ATP’s per glucose molecule
Glucose2
Pyruvate
2 NAD+ 2 NADH
2 ADP 2 ATP
Fermentationby-product
Intermediate accepts electrons from NADH
FERMENTATION PATHWAYS ALLOWS CELLS TO REGENERATE NAD+ FOR GLYCOLSIS
Glucose
2 Pyruvate
2 NAD+ 2 NADH
2 ADP 2 ATP
2 Lactate
Pyruvate accepts electrons from NADH
LACTIC ACID FERMENTATION OCCURS IN HUMANS
During heavy exercise, ATP production will switch from aerobic respiration to
anerobic respiration
Glucose
2 Pyruvate
2 NAD+ 2 NADH
2 ADP 2 ATP
2 Ethanol 2 Acetylaldehyde
2 CO2
ALCOHOL FERMENTATION OCCURS IN YEAST
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