Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Early Aerobic Bacteria
Name: Zarshis
Status: Student
Grade:  Other
Location: Outside U.S.
Country: Australia
Date: Summer 2009

I know that cellular respiration in mitochondria needs both the membranes of the mitochondria so as to maintain a proton motive gradient. If the theory of endosymbiosis is true, then how did the primitive aerobic bacteria with only a single membrane carry out respiration?


There can be a proton gradient across a cell membrane, not just across a membrane within a cell. For example, certain bacteria and archaea have a proton gradient across their membranes (inside vs. outside), and can still respire without internal membranes.

Hope this helps,

Click here to return to the Molecular Biology Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory