What does arabinose do to make the bacteria glow? The bacteria are given a heat shock, which causes some of them to take up a plasmid. To genetically transform an entire organism, you must insert the new gene(s) into every cell in the organism. Here is a typical procedure for transforming and selecting bacteria: Specially prepared bacteria are mixed with DNA (e.g., from a ligation). The effects of different antibiotics can also be demonstrated by spreading samples of an E. coli HB101 and HB101/pGLO cultures on LB plates and then placing disks containing different antibiotics on the agar surface. These preparations minimize batch-to-batch variability and significantly simplify the efficient propagation of cloned DNA. Arabinose is used by the bacterial cell as an energy source but much rather use glucose when present. Resistance to an antibiotic is known as a selectable marker because we can select for cells that contain it. If the bacteria are viable on the LB/amp plate, then they are resistant to ampicillin. The cellular machinery (e.g. 2019 National Association of Biology Teachers. Transformed colonies of E. coli HB 101 groing on LB agar plus ampicillin. For instance, when we try to insert a gene into a plasmid using a particular restriction enzyme, we may get some cases where the plasmid closes back up (without taking in the gene), and other cases where the gene goes in backwards. The most commonly used method for DNA delivery into bacterial cells is chemical transformation which involves cell . . This page titled 6.1: Genetic Transformation (using bacteria and the pGLO plasmid) is shared under a not declared license and was authored, remixed, and/or curated by Michael Blaber. Many bacteria live in mixed-species microbial communities where they compete with each other for limited space and resources [].Intermicrobial competition is mediated by a diverse array of molecular strategies that can exclude or directly interfere with other microbes, both near and far [].Nearly 25% of Gram-negative bacteria encode a type VI secretion system (T6SS) [], which . 51. A detailed structure of the plasmid is shown in Figure 1. This plasmid contains several important pieces: Bacteria that are transformed with this plasmid will have two new traits: they will fluoresce green under UV light and they will be resistant to the antibiotic ampicillin. The kits have extensive student study guides and work very reliably. This recombinant plasmid, created by researchers at Bio-Rad, combines a gene for green fluorescent protein (GFP), cloned from a jellyfish, with control elements copied from a bacterial operon.The end result is a system that allows for bacterial expression of . Direct link to tyersome's post Good question! Once prepared, competent cells should be evaluated for transformation efficiency, aliquoted to small volumes to minimize freeze/thaw cycles, and stored at an appropriate temperature to maintain viability. Arabinose (ara) binds to the araC regulatory protein made by the transformed bacteria. Metabolism without Oxygen: Fermentation, 68. 49. Promoters are usually indicated with an acronym that begins with an upper case "P". Arabinose - an overview | ScienceDirect Topics Conversely, both transformed and untransformed bacteria are inhibited by chloramphenicol and tetracycline because the enzyme has no effect on them. During bacterial. Transfer of plasmid DNA into bacteria. Each bacterium. For storage, aliquoting prepared cells in single-use volumes in screw-cap microcentrifuge tubes is recommended since each freeze/thaw cycle lowers transformation efficiency by about half. This sugar is found in several fruits apples, plums, cherries, grapes, and in juices made from these fruits. This is not a useful plasmid. Genetic engineering is the directed transfer of a gene, or piece of DNA, into a cell (typically a bacteria). Once inside, the arabinose interacts directly with AraC, which is bound to the DNA. Bacterial transformation is a key step in molecular cloning, the goal of which is to produce multiple copies of a recombinant DNA molecule. While many general biology, cell biology, biochemistry, and organic chemistry textbooks introduce carbohydrate structure, this topic is often difficult for students to follow. The glowing mice seen in Figure 1 are one example of a GMO. Bacterial strains that are used for transformation and cloning experiments have been engineered to prevent cleavage of the plasmid DNA. Heat shock the bacteria by rapidly heating and then cooling them. Make sure no air bubbles are present in the electroporation cuvette. White spotting: When there's more than two alleles, 92. A suspension of HB101 containing the pGLO plasmid is then streaked onto the plates for single colonies and growth is observed after one to two days. Why do you incubate on ice for 2 minutes? We need a way to get rid of the untransformed bacteria (greater than 99% of the total bacteria present) so that we are left with only the bacteria that were transformed with the plasmid. with 50 mM l-arabinose at OD 600 of 0.3. One of the main issues with electroporation is arcing, or electric discharge, which may lower cell viability and transformation efficiency. Brindle color: partial dominance and epistasis, 89. pGLO Transformation Lab Report - pGLO Transformation Exercise - Studocu What causes the genetically transformed bacteria to turn green? This enzyme breaks down some antibiotics such as ampicillin when they are present in the environment before they can kill the bacteria. The organism commonly used for genetic transformation and heterologous expression of human genes/proteins is the single celled bacteria known as Escherichia coli (E. coli). The bla gene includes a promoter at the 5' end of the gene. Because of these possibilities, it's important to collect plasmid DNA from each colony and check to see if it matches the plasmid we were trying to build. making mRNA molecules). MHCC Biology 112: Biology for Health Professions, https://openoregon.pressbooks.pub/app/uploads/sites/94/2021/01/ezgif.com-gif-maker.mp4, Next: Gel Electrophoresis and DNA Fingerprinting, Creative Commons Attribution 4.0 International License. Students may want to try the experiment with other E. coli strains or with bacteria of other species. After the new DNA has entered the bacteria, it is used by the cell to make RNA and then protein. In the presence of L-arabinose, the modified AraC dimer binds to sites I1 and I2, which allows the binding of RNA polymerase and the catabolite activator protein (CAP) and subsequent transcription. Charles E. Deutch; Transformation of Escherichia coli with the pGLO Plasmid: Going beyond the Kit. 1660005EDU) and for its separation from other E. coli proteins by SDS-polyacrylamide gel electrophoresis (catalog no. To demonstrate the specificity of the interaction between sugars and the AraC protein, other carbohydrates can be added to the medium instead. A sterile hockey-stick or L-shaped cell spreader is commonly used to spread the cell suspension while gently rotating the plate (Figures 6, 7A). The plasmid DNA might be used in further DNA cloning steps (e.g., to build more complex plasmids) or in various types of experiments. Transformation Quizzes Bio 211 Lab Flashcards | Quizlet The mRNA will be translated to produce low-levels of the b-lactamase protein. First, cells that contain plasmid DNA have a disadvantage since cellular resources (such as energy) are being used to replicate the plasmid and to synthesize the proteins that are encoded for by the plasmid's DNA. Green Fluorescent Protein (GFP) that will glow under UV . The protocols for preparing competent cells vary by whether transformation is to be achieved via heat shock or electroporation. Feedback Inhibition in Metabolic Pathways, 67. (3) Can pGLO be introduced into eukaryotic microbes such as yeast? In transformation, the DNA (usually in the form of a plasmid) is introduced into a . Prior steps for creating recombinant plasmids are described in traditional cloning basics and involve insertion of a DNA sequence of interest into a vector backbone. Search for other works by this author on: Revisiting the mechanism involved in calcium chloride induced bacterial transformation, Studies on the chemical nature of the substance inducing transformation of pneumococcal types. It was originally isolated from the jellyfish Aquorea victoria. The protein encoded by the target gene accumulates inside the bacteria. The essential sequences include the following: GFP jellyfish gene that encodes green fluorescent protein (GFP) medium may be pelleted by centrifugation for 5 minutes at 600800 x g and resuspended in a smaller volume for plating. Search The interaction of arabinose + araC protein stimulates transcription of the GFP gene. TRANSFORMATION - Laboratory Exercises in Microbiology Bacteria can take up foreign DNA in a process called, Transformation is a key step in DNA cloning. Keep the volume of the DNA solution at no more than 5% of the total cell suspension volume (e.g., 2 L DNA per 40 L of cells). This project can be extended by looking at the effects of other sugars on the fluorescence of the colonies in transformants containing pGLO in the presence of low concentrations of L-arabinose. The pGLO plasmid contains an origin or replication, a selectable marker, and the gene for Green Fluorescent Protein (GFP). Therefore, there is always tremendous pressure on cells to get rid of their plasmids. Solved II. Transformation of E. coli with Plasmid DNA (PGLO) - Chegg This is a weak constitutive promoter (always "on" at a low-level). 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.g., Bergmans et al., 1981; Chan et al., 2013; Asif et al., 2017). What would happen to araBAD if AraC were missing? Here, I describe some extensions of the pGLO transformation experiment that can be used to explore aspects of the system in more detail and to demonstrate other biological concepts. process of bacterial transformation revolves mainly around the plasmid needed for bacteria's . { "6.1:_Genetic_Transformation_(using_bacteria_and_the_pGLO_plasmid)" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass230_0.b__1]()", "6.2:_Enzyme_kinetics" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass230_0.b__1]()", "6.3:_Ligand_binding" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass230_0.b__1]()", "6.4:_Restriction_Mapping" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass230_0.b__1]()", "6.5:_Polymerase_Chain_Reaction_(PCR)" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass230_0.b__1]()", "6.6:__Use_of_PC_and_internet_for_biochemical_research" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass230_0.b__1]()" }, { "00:_Front_Matter" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass230_0.b__1]()", "1:_DNA" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass230_0.b__1]()", "2:_Bacteria" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass230_0.b__1]()", "3._Biotechnology_1" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass230_0.b__1]()", "4._Biotechnology_2" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass230_0.b__1]()", "5._Lab_Notes_Part_1" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass230_0.b__1]()", "6._Lab_Notes_Part_2" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass230_0.b__1]()", "zz:_Back_Matter" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass230_0.b__1]()" }, 6.1: Genetic Transformation (using bacteria and the pGLO plasmid), [ "article:topic", "transformation", "E. coli", "showtoc:no", "authorname:mblaber", "pGLO plasmid" ], https://bio.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fbio.libretexts.org%2FBookshelves%2FBiochemistry%2FSupplemental_Modules_(Biochemistry)%2F6._Lab_Notes_Part_2%2F6.1%253A_Genetic_Transformation_(using_bacteria_and_the_pGLO_plasmid), \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}}}\) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\). 1. A method for increasing electroporation competence of Gram - Nature The ampicillin kills any cell that did not get transformed with the plasmid. Arabinose is a five-carbon sugar that is found widely in nature and can serve as a sole carbon source in many bacteria. In the presence of D-glucose, less cAMP is formed and binding of the CAP/cAMP complex to the CAP-binding site adjacent to the araBAD promoter is reduced, limiting expression of the arabinose genes. Inside each bacterium, the target gene is transcribed into mRNA, and the mRNA is translated into protein. Protein production and purification. Prior steps for creating recombinant plasmids are described in traditional cloning basics and involve insertion of a DNA sequence of interest into a vector backbone. Right: gene goes into plasmid backwards (pointing back towards the promoter sequence). Restriction digests. Zhang et al. DNA is the genetic material in all living cells and ultimately determines much of an organism's phenotype. For example, do not use your hands to put a sterile pipette tip on your pipettor, and only touch the handle end of an inoculating loop (not the loop end which will touch the bacteria). There are two origins of replication and numerous sites for restriction endonucleases within the plasmid genome. We will use aspects of aseptic technique during our bacterial transformation labs to prevent our plates and bacterial samples from becoming contaminated. HB F'20 - Lab 7 Week 2 Post-Lab Assignment - Studocu In the pGLO plasmid DNA, some of the genes involved in the breakdown of arabinose have been replaced by the jellyfish gene that codes for GFP. However, some instructors may want to combine them into a longer lab project that extends over several periods. Bacteria without a plasmid die. For instance, plasmids were used to deliver a human gene to lung tissue in a recent gene therapy clinical trial for patients with the genetic disorder cystic fibrosis. This is the desired plasmid from the ligation. In bacteria, the expression of many degradative genes is controlled by a process called carbon catabolite repression (Brckner & Titgemeyer, 2002). The bacteria in the large culture are induced to express the target gene through addition of a chemical signal to the culture medium. A colony containing the right plasmid is grown in bulk and used for plasmid or protein production. How is the pGLO plasmid introduced into the E. coli cell? Griffith showed that a substance from heat-killed virulent bacteria could transform live avirulent ones into organisms that could kill mice. The GFP gene is located on the pGLO plasmid. Copyright 2023 National Association of Biology Teachers. Do you observe some E coli growing on the LB plate that does not contain ampicillin? When a ligation mixture is used as the transforming DNA (often 15 L is sufficient), purification prior to chemical transformation is generally not required. Direct link to Mishgan Fatima's post My textbook says small si, Posted 4 years ago. GFP originates from a jellyfish and it is often used in biotechnology to mark certain cells, or as a reporter gene that indicates if a cell expresses a certain protein. Larger vectors are more likely to contain duplicates of the restriction sites and so are harder to work with you typically will cut at unique restriction site(s) when cloning, but these are harder to find in larger vectors. To calculate the transformation efficiency, divide the number of transformants by the amount of DNA added, and factor in cell dilution (if performed), using the following formula: With ligated DNA, the amount of DNA added to the cells can also be determined from the ligation reaction setup, DNA dilution (if performed), and DNA volume for transformation, using the following formula: 50 ng of DNA is ligated in a 20 L reaction. In the absence of arabinose, a dimeric AraC protein binds to sites I1 and O2, forming a loop in the DNA and blocking the binding of RNA polymerase to the PBAD promoter site. Can we use Calcium chloride in Solution to make bacteria more permeable instead of Heat Shock? This step improves cell viability and cloning efficiency. https://edvotek.wordpress.com/2014/07/18/biotechnology-basics-bacterial-transformation/, https://www.khanacademy.org/science/biology/biotech-dna-technology#dna-sequencing-pcr-electrophoresis. Avery, MacLeod, and McCarty later identified this transforming principle as DNA (Avery et al., 1944). The transformed bacterial colonies glow green when illuminated with the UV light. Arabinose turns on the expression of the GFP gene. It is an inducing substrate that allows the transcription of the gene of interest. then how it works?? Background. Cells should not be frozen or stored in liquid nitrogen, as this practice drastically reduces viability. We utilized a plasmid in class called pGLO. To overcome the pressure to get rid of the plasmid, we must provide an advantage to the cells that have and keep the plasmid. . The GFP is transcribed by the arabinose PBAD promoter. After transformation, unused competent cells (prepared for either method) may be refrozen. Thus, Production of the outer cell membrane/proteoglycan structure is inhibited In the presence of ampicillin (a lethal event for the bacteria), The presence of green light from E. coli cells indicates that the transformation (and drug resistance selection) has been successful, GFP is a gene from a jelly fish and is the reason that some jelly fish glow green. The bacteria are given a heat shock, which "encourages" them to take up a plasmid. These cells will produce GFP at very low levels and will appear whitish when viewed under UV light. In the presence of L-arabinose, the dimeric L-arabinose/AraC complex has a different conformation and binds to sites I1 and I2. Xylose and arabinose is the major constituents of hemicellulose, large quantities of which are found in agricultural waste, such as rice straw, corncobs, and parts of hard wood. For simplicity, I have made up standard LB agar plates and then spread them with 100 L of a filter-sterilized 10 mg mL1 solution of ampicillin and 100 L to 200 L of a filter-sterilized 60 mg mL1 solution of a specific sugar. Extracellular matrix and intercellular junctions, 28. Electroporation involves using an electroporator to expose competent cells and DNA to a brief pulse of a high-voltage electric field (Figure 3B). Wouldn't it be hard to find a restriction enzyme for a particular gene of interest because the desired gene must have the recognition site for the restriction enzyme on both ends? Typically the intent is to force the cell to express (produce) the protein that the newly introduced piece of DNA codes for (known as heterologous expression). Check out this, Do you want to learn more about the selection of transformed bacteria? Most bacteria do not take up a plasmid, but some do. You should never touch the sterile portion of a piece of equipment with your hands before you use it, even if your hands are clean. Arabinose - an overview | ScienceDirect Topics By continuing to use our website, you are agreeing to, A Glucose Metabolism Web Game for Diabetes Education. Left: gene goes into plasmid forwards (pointing in the same direction as the promoter sequence). Direct link to Tavis Jorgensen's post How can reporter genes be, Posted 4 years ago. In addition to their DNA genome (which is circular), bacteria can also contain additional smaller circles of DNA called plasmids. If the plasmid contains a gene for resistance to an antibiotic, then after transformation, bacteria grown on a nutrient plate containing the antibiotic will not be inhibited or killed by it. Promoters are typically located at the start (5' end) of a gene that codes for a protein (since mRNA production proceeds 5'->3'). All rights reserved. The pGLO plasmid contains a gene (bla or ampR) for a protein called -lactamase, which hydrolyzes antibiotics that have a -lactam ring and makes host cells resistant to compounds like ampicillin. In this approach, 10 to 20 beads are placed on the plate after applying the cell suspension, and the plate is gently swirled so that the cell suspension is spread by the beads (Figure 7B). (4) How can the intensity of the color of the GFP fluorescence be quantified? coli is grown on d-arabinose, all of the enzymes necessary for immediate growth on l-fucose are present. In order to "stably retain" the plasmid, there needs to be some type of metabolic reason for the E. coli to keep the plasmid around. When transformed bacteria are grown on plates containing LB nutrients + ampicillin + arabinose, the arabinose interacts with the araC protein (which is produced from the araC gene). In a healthcare setting, it is used to prevent spreading dangerous microorganisms between patients. ribosomes) will translate this mRNA into corresponding GFP protein. As they produce more and more protein, the cells expressing GFP fluoresce a brilliant green. After ligation, the reaction is diluted 2-fold and 5 L of the diluted ligation mixture is added to 100 L of competent cells for transformation. My textbook says small size vectors are preferred for cloning. Why does it matter if a gene goes into a plasmid backwards? The contents of each tube are then plated on their respective plates . Bacteria that are able to easily take up DNA from the environment are called competent. What happens next? Do you want to learn more about bacterial transformation? With chemical transformation,chemically competent cells are mixed with plasmid DNA and briefly exposed to an elevated temperature, a process known as heat shock (Figure 3A). This means that the only colonies growing on a nutrient + antibiotic plate after a transformation are the bacteria that acquired and kept the plasmid. Bacteria contain many proteins and macromolecules. Bio-Rad's pGLO Bacterial Transformation Kit is the classic kit for teaching the central dogma and the basics of genetic engineering. Changes in number of genes or chromosomes, 52. In some cases, bacteria are simply used as "plasmid factories," making lots of plasmid DNA. Some of the main buffers that many labs use are: Why cant bacterial plasmid vectors be used to transform plant cells? To log in and use all the features of Khan Academy, please enable JavaScript in your browser. Transcription and metabolism of the operon does not occur. It occurs after. For successful chemical transformation, 50100 L of competent cells and 110 ng of DNA are recommended. Because of this, the newly made protein needs to be. Plasmids used in cloning contain an antibiotic resistance gene. Yes. Following heat shock or electroporation, transformed cells are cultured in antibiotic-free liquid medium for a short period to allow expression of antibiotic resistance gene(s) from the acquired plasmid to begin (Figure 5). After transformation, the cell suspension is diluted 5-fold and 200 L of the diluted cells are plated. Thus, the protein is trapped in the column while other molecules from the bacteria flow through. When ready for the transformation step, competent cells should be thawed on ice and handled gently to retain viability. Arabinose acts as an allosteric regulator of AraC, changing which DNA sites it binds to and how it forms a dimer. Normal E. coli are not competent, however, if they are treated with a solution of calcium chloride their cell membranes become competent. The new proteins produced from this DNA are what cause the change in the traits of the cells. Alternatively, autoclaved glass beads (4 mm diameter) may be used to spread the cells. Urinary levels higher than the reference range may simply reflect a high dietary intake of these fruits. It will instruct RNA polymerase to continually make a low-level of mRNA for this gene. For Research Use Only. With ara bound to it, araC activates RNA polymerase to bind to the promoter in front of the GFP gene. Competent cells should remain stable for approximately 612 months when stored at 70C with minimal temperature fluctuations. The standard protocol for pGLO transformation of E. coli strain HB101 calls for adding L-arabinose to LB medium at a concentration of 6 g L1 along with ampicillin at a concentration of 100 mg L1. The two most popular methods of bacterial transformation are (1) heat shock of chemically prepared competent cells (chemical transformation), and (2) electroporation of electrocompetent cells. medium, the cells are plated on LB agar with appropriate antibiotic(s) or other agents for identification and recovery of successful transformants. In the absence of arabinose, a dimeric AraC protein binds to sites I1 and O2, forming a loop in the DNA and blocking the binding of RNA polymerase to the PBAD promoter site. Biotechnology in Medicine and Agriculture, 103. Figure 6.1.4: pGLO Plasmid. This protein production only occurs once the plasmid has been incorporated into the bacteria. Typically, fewer than 1 in 1000 bacteria will acquire the plasmid (Figure 5). Please check the following possibilities and suggestions for getting no colonies: Check the antibiotic used. pGLO Transformation and Inquiry Kit for AP Biology | Bio-Rad In this lab, it is not necessary to wear gloves since the bacteria that we are using are not all that dangerous, but you should wash your hands before you start the lab and again before you leave the lab room. Why? You should also clean the surface of your lab bench at the start and end of lab, as directed by your instructor. Genetic engineering is the directed transfer of a gene, or piece of DNA, into a cell (typically a bacteria). Opponents of the technology claim that GMOs pose a health risk to humans as well as potential environmental risks. The plasmid that we will be using is called pGLO (available from Bio-Rad). FIG. Transformation of bacteria is the process by which a bacterial cell takes up DNA from the environment and incorporates some of the information into its own. This means that bacteria that took up the plasmid during transformation can be distinguished from bacteria that did not by growing the bacteria on a nutrient plate containing the antibiotic (Figure 6). Well, they canbut it depends what kind of bacteria and what kind of plasmid. What is the role of arabinose in bacterial transformation? When there is an abundance of arabinose, we want gene expression to occur, but when . A chosen colony is grown up into a large culture. Making cells competent renders their cell membrane more permeable to DNA. Bacterial Transformation The molecules extracted from the cells are applied to a column that contains antibodies specific for the target protein. Supporters of GMOs believe that the benefits such as increasing the available food supply, increasing the nutritional content of foods, and the production of medicine outweigh the risks.