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 Yeast and Lactose
Name: Kate
Status: Other
Grade:  Other
Location: CA
Country: United States
Date: April 2005


Question:
Our class performed an experiment where yeast was placed into 2 tubes, one containing glucose and the other containing lactose. Growth occured in the tube with glucose and a gas bubble formed indicating the yeast was able to perform fermentation. No growth however occured in the tube with lactose and i dont understand why? is it because the yeast was unable to break the lactose down into glucose?



Replies:
Yes. There is an enzyme, beta-galactosidase or lactase, that breaks lactose down into glucose + galactose. If the yeast don't produce this enzyme, they are unable to use lactose as a carbon and energy source.

Ron Baker, Ph.D.


You are absolutely correct! Remember that all biochemical reactions require enzymes to make reactions occur at useful rates. There is an enzyme that catalyzes the breakdown of lactose into glucose. Enzymes are proteins and therefore are coded for by genes and the yeast you used doesn't have this gene. I will let you look up the name of this enzyme.

vanhoeck



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 (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