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 E. coli DNA
Name: Bala
Status: Student
Grade:  9-12
Location: IN
Country: United States
Date: June 2006

What is the difference between genome and plasmid of E.coli.? Is the DNA in plasmid be considered as a part of genome?

They are both part of the whole genome of the bacteria. Since scientists have genome databases just for plasmids, there is some sense in considering the plasmid genome separate from the single bacterial chromosome. The whole genome being ALL the DNA sequences of the bacteria.


The genome of *E. coli* is a single,circular DNA molecule comprised of about 4 million base pairs encoding approximately 3,000 genes. Typical bacterial plasmids are circular DNA molecules containing around 50,000 base pairs. Since some strains of bacteria do not contain plasmids, they are not a an essential part of the genome.

Ron Baker, Ph.D.

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