Gene Regulation Lab Report

Introduction

Gene regulation is the process of turning a gene on or off. Genes are a section of DNA that encodes information. (Freeman, 2014, p.305) In the human body there are tons of cells that each contain different genes. All of the genes cannot be expressed at once so cells must decide which genes to turn on and off. An operon is a part of DNA found in bacteria that controls gene regulation. Operons are controlled by an on switch known as the promoter. The Promoter is a place where the protein RNA polymerase binds. RNA polymerase is an enzyme that binds to DNA during transcription and unravels the DNA strands. RNA polymerase also transcribes the sequence of a messenger RNA (mRNA) molecule. (Goldberger, 1979, p.2)

In this experiment the

In the lac operon of E.coli, lactose induces the synthesis of the enzyme, beta-galactosidase. This enzyme codes for the Lac Z gene and thus, when synthesized properly with no other affecting factors, would break down ONPG. If lactose is not present in the enzyme, then the Lac I gene would continue to block transcription of the genes are also not synthesized. The primary regulator of the lac operon is a negative control element known as the lac regulatory protein which acts as a repressor when binded to a gene, turning the expression of the gene off. The repressor is a regulatory protein that binds to the operator and blocks transcription of the genes of an operon. Inducers bind to the repressors and they also regulate gene expression. In the process of identifying the three strains of E.coli, ONPG (ortho-nitrophenyl b-D galactoside) was used as an indicator. ONPG is a substrate that can detect B-galactosidase, and when it does, it turns yellow. Sarkosyl was also a detergent used in the lab to lyse open cells. In the lab we predicted that the E.coli wild type would be clear for distilled water and sucrose but yellow for lactose. E.coli Lac I- would be yellow for all and Lac Z- would be clear for

Calculated beta-Galactosidase Activity (miller units)

This is a bar graph of the data displayed in table 1.

According to the data displayed in (Table 1) and (Figure 1), E.coli strand A remained clear under the condition of distilled water, yellow under of 5% lactose and clear under the of 5% sucrose. E.coli strand B also remained clear under the condition of distilled water, it turned yellow under 5% lactose and remained clear under the 5% sucrose. E.coli strand C turned yellow under the conditions of distilled water, clear under 5% lactose and yellow under 5% sucrose.

The E.coli strain B was slightly different from E.coli strand A and C under distilled water. Both E.coli strain A and C were negative while strain C was positive. There was a minute difference between E.coli strain C compared to strain A and B under the condition of 5% lactose. Both strain A and B were positive and strand C was negative. There was a significant difference in E.coli strand C under sucrose compared to E.coli strain A and B. Strain A and B were both positive while strain C was negative.