Why does arabinose

On the other hand, other E. Students may want to try the experiment with other E. Most of these extensions are relatively short and easy to do, and so several of them could be done in a single lab session. However, some instructors may want to combine them into a longer lab project that extends over several periods.

The DNA can then be examined by agarose gel electrophoresis and imaged using either ethidium bromide with a UV transilluminator or a blue stain and a white light illuminator. The DNA can then be cut with various restriction endonucleases and analyzed in more detail. Figure 1 shows the sites of cleavage by many restriction endonucleases. The standard protocol for transformation of E.

There have been many investigations and modifications of this process, which involves the formation of competent cells, the uptake of DNA, and the recovery of transformed cells e. The transformation of E. Because the pGLO system is both accessible and open-ended, it is suitable for student projects at several different levels. Among the other questions that students may want to explore are 1 How can this system be used to demonstrate that DNA is the genetic material?

Instructors who have found experiments they like in these kits might want to develop similar extensions to those described here. I thank the students in BIO Genetics Laboratory at Creighton University for trying out many of these extensions of the pGLO transformation experiment in the fall semesters of and I also thank the faculty and staff in the Department of Biology at Creighton University for their hospitality while I was there.

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Specificity of Carbohydrate—Protein Interactions. Further Extensions. Article Navigation. Research Article January 01 Deutch Charles E. This Site. Google Scholar. These three genes can now be transcribed and the resulting RNA can be translated into protein. Thus, araC negatively controls its own expression and positively controls BAD.

Here is a summary figure of the arabinose operon:. Comparison of original arabinose operon with the GFP modified operon. This expression system has given us excellent results. We follow up the GFP production with a purification step, which looks like this:. The protein that was produced in the first picture above green and blue glowing bacteria used a different expression system involving the lac operon. The lac operon is induced by IPTG , an analog or similarly shaped molecule to lactose.

Here is a diagram showing how the IPTG induction works:. Lactose is another sugar that can be used as an energy source by bacteria like E.

Bacteria have three genes involved in metabolizing lactose when it is the only carbon source present bacteria will use glucose first if both lactose and glucose are present : lacZ , lacY , and lacA. When lactose is absent, the repressor binds to the operator which overlaps the promoter region and prevents transcription of the XYA genes.

When lactose is present it binds to the repressor protein and prevents it from binding to the DNA operator. Chromatin Remodeling in Eukaryotes. RNA Functions. Citation: Brown, W. Nature Education 1 1 Can the presence of glucose itself activate the genes that will break it down? It does in bacteria through a process known as positive transcription control.

Aa Aa Aa. Figure 3. Figure Detail. References and Recommended Reading Englesberg, E. Article History Close. Share Cancel. Revoke Cancel. Keywords Keywords for this Article. Save Cancel. Flag Inappropriate The Content is: Objectionable. Flag Content Cancel. Email your Friend. Submit Cancel. This content is currently under construction. Explore This Subject. Consequences of Gene Regulation. Gene Responses to Environment. Regulation of Transcription.

Transcription Factors. From DNA to Protein. Organization of Chromatin. Topic rooms within Gene Expression and Regulation Close. No topic rooms are there. Or Browse Visually. Other Topic Rooms Genetics. Student Voices. Creature Cast. Bio-Rad Products Explore all. Support Explore all. Clinical Diagnostics Explore all.

Process Separations Explore all. Food Science Explore all. Bio-Rad Products Back. Life Science Education Explore all. About the Program Explore all. Corporate Explore all. About Bio-Rad Back. About Bio-Rad Explore all. Investor Relations Explore all. Bacterial Transformation With pGLO bacterial transformation, students learn about genetic engineering as they transform a non-virulent laboratory strain of Escherichia coli E. Gene Regulation Gene expression is carefully regulated to allow organisms to adapt to differing conditions and prevent wasteful production of proteins.

When arabinose is absent, the AraC protein binds to the DNA at the binding site for RNA polymerase, preventing transcription of the digestive enzymes When arabinose is present, it interacts with AraC, causing AraC to change shape, allowing RNA polymerase to bind the promoter; araB , araA , and araD are then expressed and can do their job to break down arabinose until the arabinose runs out The pGLO plasmid contains both the promoter pBAD and araC gene, but araB , araA , and araD have been replaced by the single gene that codes for GFP, which serves as a reporter gene.

Green Fluorescent Protein GFP has a barrel structure surrounding a central alpha helix that contains the fluorophore.