1238116 lab report on the induced synthesis of beta -...

Running head: LAB REPORT 1
Lab Report on Catabolite Repression and Induction of Beta-galactosidase Synthesis in E . coli
Name
Professor
Course
Institution
Date

LAB REPORT 2
Lab Report on Catabolite Repression and Induction of Beta-galactosidase Synthesis in E . coli
Abstract
The major aim for the experiment is to demonstrate both catabolite repression and
induction of beta-galactosidase synthesis during growth of E. coli. Synthesis of the enzyme beta-
galactosidase is induced in wild type E. coli strains in response to the presence of lactose, the
enzyme's natural substrate. Apart from induction, synthesis rate is determined by catabolite
repression, whereby it slows down the synthesis of beta-galactosidase especially in the presence
of a better carbon (and energy) source, such as glucose. In this experiment, Escherichia coli ( E.
coli ) is used as the bacteria to induce synthesis of enzyme β-galactosidase. The results support
lactose metabolism by newly synthesised beta-galactosidase and also, quantitatively, IPTG is a
more effective inducer of beta-galactosidase synthesis than lactose.

LAB REPORT 3
Introduction
In order to regulate the gene expression levels in a cell, there are certain mechanisms that
must be considered in operation. In which case, the regulation are considered at transcription and
translationt levels or the stability of messenger RNA. The aforementioned can only work in
regulation based on the synthesis of a particular protein. Consequently, it comes out as a subject
of importance to investigate the regulation of transcription of bacterial genes. For this case,
Escherichia coli ( E. coli ) is used as the bacteria to induce synthesis of enzyme β-galactosidase.
Escherichia coli ( E. coli ) can produce the enzyme β-galactosidase which breaks lactose into
galactose and glucose. Synthesis of the enzyme beta-galactosidase is induced in wild type E.
coli strains in response to the presence of lactose, the enzyme's natural substrate (Ring, 1999,
80). The inducer, lactose, is usually the molecule broken down by the enzyme system. Worth
noting is the ability of E.coli to solely use lactose as a carbon source regardless of the presence
of glucose. However, for E.coli to metabolise lactose there is need for the presence of beta-
galactosidace, to act as a catalyst in the hydrolisis of lactose.
Synthesis of the enzyme is also subject to catabolite repression , thereby slowing down
the synthesis of beta-galactosidase especially in the presence of a better carbon (and energy)
source, such as glucose(Wallenfels, 1972, 67). When given both sugars, E.coli will not
synthesize beta-galactosidase until all of the glucose is first exhausted from the medium.