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Aerobic Respiration

Aerobic respiration is a cellular process for harvesting energy. Electrons are extracted from an electron donor and transferred to O2 as the terminal electron acceptor. This process generates a membrane potential across the cytoplasmic membrane termed proton motive force (pmf). The pmf is then used to drive ATP synthesis via the membrane-bound ATP synthase (electron transport phosphorylation).

Key Concepts

  • Aerobic respiratory chains are located in the cytoplasmic membrane and are used to generate a proton motive force (pmf).
  • Aerobic electron transport chains always contain a dehydrogenase enzyme that donates electrons to cytochrome oxidase that reduces O2 to H2O.
  • Ubiquinone (Q) mediates electron mediator between the two enzymes.
  • The proton motive force drives ATP synthesis via the membrane-bound ATP synthase.
  • Cytochrome oxidases with different affinities for O2 allow E. coli to grow under aerobic and microaerophilic conditions.

Principles of aerobic Respiration

Aerobic respiration is a process that provides energy for cell growth under aerobic and microaerophilic conditions. Oxygen is always used as the terminal electron acceptor.

 

How E. coli Respires with oxygen

When E. coli grows by oxidizing carbohydrates such as glucose, NAD is reduced to NADH. This cellular intermediate then serves as the electron donor for aerobic respiration.

2 NADH + 2 H+ + O2    2 NAD+ + 2 H2O

 

 

 

Enzymes employed in aerobic respiration:

The cytochrome oxidases:

  • Cytochrome bo oxidase (CyoABCD).       
  • Cytochrome bd-I oxidase (CydAB).       
  • Cytocrome bd-II oxidase (AppBC).       

The dehydrogenases:

  • NADH dehydrogenase I (NuoABCDEFGHIJKLMN).       
  • Succinate dehydrogenase (SdhCDAB).       

 

Credits:

Authored by Robert Gunsalus and Imke Schröder
©The Escherichia coli Student Portal

This project acknowledges support from:
NIH Grant Award GM077678 to SRI, International
Peter Karp and coworkers at EcoCyc.org
The UCLA Department of MIMG