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 Ampicillin and Bacteria
Name: sara
Location: N/A
Country: N/A
Date: N/A


Question:
could you please explain fully how ampicillian destroys E.coli cells?



Replies:
Ampicillin is an antibiotic belonging to the group of beta-lactam antibiotics. These will kill Gram-negative bacteria to which E.coli and Salmonella belong. The antibiotic prevents the formation of peptidoglycan, an essential building block of the cell membrane. So the antibiotic prevents growth of cells.

You can read more about antibiotics and how bacteria can become resistant against them at the Virtual Bacteria of Bacteria: http://www.bacteriamuseum.org

Dr. Trudy wasenaar


Unfortunately, I don't have my micro books with me, but I'll try. Bacteria have a unique compound in their cell walls called peptidoglycan. It is made of 2 types of sugar residues that are cross-linked (like a chain link fence) by tetrapeptides. Penicillin prevents the crosslinking of the sugars by breaking the tetrapeptides. These antibiotics are more effective against gram positive organisms (such as Staph.) than gram negative organisms (such as E coli) because gram pos. have more peptidoglycan in their cell walls. Some bacteria have adapted to this situation by having an enzyme called beta-lactamase that breaks the structure of the antibiotic open rendering it ineffective. I'm pretty sure ampicillin is a penicillin derivative and therefore has the same mode of action, but I would check to make sure if I were you.

Van Hoeck



Click here to return to the 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 (help@newton.dep.anl.gov), or at Argonne's Educational Programs

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

Argonne National Laboratory