Isolation, restriction digestion, and gel electrophoresis of plasmid DNA
Prathyusha Gudapati, BIOL 304, spring 2015.
Abstract
The purpose of the experiment was to isolate plasmid DNA, followed by restriction digestion using restriction endonucleases and then visualizing the digested fragments after subjecting to gel electrophoresis. Plasmid DNA (pSP72 DNA) was isolated from Escherichia coli KAM32 (E.coli) cultures using the QIA prep miniprep kit and then subjected to restriction digestion by EcoRI and HindIII. The restriction digested DNA was then loaded into the wells of 0.7% agarose gel and subjected to electrophoresis. It can be concluded from our results that our plasmid DNA isolation was successful and the restriction digestion results were partially in agreement with our hypothesis.
Introduction
Plasmids are small double stranded circular non chromosomal DNA molecules containing their own origin of replication. Hence, they are capable of replication independent of the chromosomal DNA in bacteria. Plasmids present in one or more copies per cell, can carry extra chromosomal DNA from one cell to another cell and serve as tools to clone and manipulate genes. Plasmids used exclusively for this purpose are known as vectors. The genes of interest can be inserted into these vector plasmids creating a recombinant plasmid. Recombinant plasmids can play a significant role in gene therapy, DNA vaccination, and drug delivery [Rapley, 2000].
We hypothesized that plasmid DNA
This pBlu lab had for purpose to present the changes of the strain of E. coli bacteria due to new genetic information being introduced into the cell. In this experiment we are freezing and heat shocking the E. Coli bacteria that is then forced to take the plasmid DNA. The E. coli then transforms the pBLu plasmid, which carries the genes coding for two identifiable phenotypes. After following the Carolina Biological steps our lab worked well and we able to see some colonies of bacteria on the plates. The x-gal plate showed a significant amount of bacteria to confirm that the pBlu plasmid took over the E. coli strain.
This lab is about moving genes from one thing to another using plasmids. Plasmid has the ability to replicate, so it replicates independently, and separately from the chromosomal DNA. Plasmid are one or more small piece of DNA and they enter cells as a double strand DNA. When they enter the cell as a doubke strand they do not invade he chromosomal DNA. We will also transform bacteria into GFP which is mainly from the jelly fish Aequorea Victoria. The GFP causes the the jelly fish to fluorescent and glow in the dark. After the transformation, bacteria starts to make the GFP which causes them to glow a green color under a ultraviolet light.
134). They are loops of DNA that are separate from the chromosomal DNA and can self-replicate in a cell, found mostly in bacteria (Brown, 2011; Addgene, 2015). Lederberg and William Hayes discovered that plasmids were being transferred from one cell to another, not the chromosomal DNA (Brown, 2011, p. 135). This discovery lead to plasmids being an essential tool for scientists. Scientists can engineer plasmids to have specific genes to introduce into new cells (Brown, 2011, p. 134). On a plasmid loop there will be an origin of replication (ORI) and a multiple cloning site (MCS) where the gene of interest is inserted (Bio-Rad, 2015). This region has specific restriction enzyme recognition sites, which are cut by the enzymes to open up the DNA where the new gene will be inserted (Jove Science Education Database, 2015). Most plasmids will also contain an antibiotic resistance gene allowing cell survival in environments containing antibiotics (Jove Science Education Database, 2015).
First, 50 uL of bacterial cells were made competent by being treated with 590 uL of CaCl2 in three different test tubes before transformation of the plasmids took place. In order to enhance the uptake of the plasmid DNA the instructor added the CaCl2 solution to the bacterial cells. The tubes were placed into a cold ice bath for about ten minutes after the CaCl2 solution was added into the test tubes of E. Coli.
In this investigation pUC19 plasmids were used as the vector due to its small size of 2686bp, high uptake efficiency by the host and fast replication time. Important features of this plasmid include the origin of replication and multiple cloning sites (MCS). The origin of replication allows the plasmid to replicate inside the host bacterium. The MCS is located within the lacZ gene and contains unique sites for the Xbal & EcoRI restirction enzymes to cut and produce sticky ends for the CIH-1 gene to bind to. Furthermore, the pUC19 plasmid also contains an ampiccilin resistance gene so only transforemed E.coli are able to remain viable when spread on the agar plates that also has the addition of ampiccilin. The lacZ gene encodes the β-galactosidase enzyme which aids in indentifying the recombinant E.coli from the non recombinant cells (Coventry University 2016).
DNA. The isolated plasmids are ran on 40 ml 1% agarose gel at 110 volts with 1.2 μl 6X track
Restriction Enzyme Digestion – The experiment was begun after putting on gloves to avoid any chemical contact with the skin. Four microtest tubes were obtained, and each of them was labeled to contain the different enzymes or suspect DNA. Two of the microtest tubes were used for suspect one and the two different restriction enzymes, while two other microtest tubes were labeled for suspect two and the two restriction enzymes. After labeling the tubes, the contents that were at the bottom were taken out by slightly tapping them. Then to begin setting up the enzyme reactions, a micropipette was used to obtain 10 μL of the reaction buffer which was added to each of the four test tubes. The buffer is important because it carries the electrical current from the power supply in the gel. After the reaction buffer was in each, the microtest tubes were individually filled with their specific enzymes and DNA, shown in summary through Table 1.1 below. The restriction enzymes are used to cleave the DNA at specific
For this experiment, E. coli was best for genetic engineering because of their size, and their fast reproduction (Spilios, 2017). E. coli will be genetically transformed using an engineered plasmid. A plasmid is a circular piece of DNA which independently replicates and multiplies because it has its own origin of replication (Spilios, 2017). The pGLO is the plasmid used in this experiment. Plasmids are used as vectors and they contain manipulated genes such as genes coding for antibiotic resistance for drugs like ampicillin. This antibiotic resistance of such serves as the selectable marker in genetic transformation and for genetic transformation to proceed, the cell must reach competency which is the physiological state that is required for the vector plasmid to get into the cell for transformation (Spilios, 2017). While competency can be reached naturally in some organism, it must be reached artificially in E. coli through treatment with CaCl2 and exposing them to heat shock using incubation (Spilios, 2017).
Genetic engineering is used in health treatments, agricultural applications, and environmental solutions. Genetic transformations incorporate foreign genetic material into the DNA of a different organism via a vector, which carries the genetic material. Plasmid DNA is small, round, and autonomous, due to its origin of replication. In biotechnology, plasmids carry beneficial genes, such as antibiotic resistance, and also a reporter protein, in this case, Green Fluorescent Protein
Restriction enzymes cut DNA at certain sites to create multiple DNA fragments. Restriction enzyme HindIII has known DNA fragment lengths and recognition sites when digesting lambda DNA, while the lambda DNA recognition site for restriction enzyme XhoI is unknown. The goal of this study is to determine the lambda recognition site of XhoI by comparing a HindIII digest and a HindIII and XhoI double digest on an electrophoresis gel. The HindIII digest had a band at 9.4 kb, but this band was not visible in the double digest, therefore we concluded the recognition site for XhoI was around 9.4kb. There were also two additional DNA
Isolation of plasmid DNA from three cultures of E.coli using a method known as the alkaline lysis method.
After the incubation, 1.5 mL of each of the three cultures were added to eppendorf tubes and centrifuged at 13,200 rpm for 1 minute. An alkaline lysis procedure like that of Birnboim and Doly was then performed to extract the plasmid DNA with 200 μl of alkaline SDS detergent solution (Birnboim & Doly, 1979). After
Bacterial transformation is the process of moving genes from a living thing to another with the help of a plasmid.The plasmid is able to help replicate the chromosomes by themselves; laboratories use these to aid in gene multiplication. Bacterial transformation is relevant in everyday lives due to the fact that almost all plasmids carry a bacterial origin of replication and an antibiotic resistance gene(“Addgene: Protocol - How to Do a Bacterial
The chemical and reagents used for the extraction and quantitation of DNA were: Plant DNAzol (0.3ml/0.1g), 100% ethanol (100%: 0.225 ml/0.1 g, 75%: 0.3 ml/0.1 g), Chloroform (0.3 ml/0.1 g), Plant DNAzol-ethanol solution: Plant DNAzol, 100% ethanol (1:0.75 v/v), TE buffer (10 mM Tris, 1 mM EDTA pH 8.0), 1.2% agarose gel (Agarose, 1X TAE buffer), 6X loading buffer (glycerol, Tris/EDTA pH 8.0, ethidium bromide), .25X TAE buffer, Restriction enzymes and Restriction endonuclease buffers. All the chemicals used were quality grade. The restriction
Plasmid DNA with Restriction Digest: The purpose of restriction digest of plasmid DNA is to understand how each DNA plasmids was cut with the given restriction enzymes and perform gel electrophoresis to observe the samples. Nine restriction digests were created, containing three digests for each of the three plasmid DNAs identifying as recombinant, non-recombinant, and unknown. Out of the nine digests, six are actual digests and three are undigested controls. A master mix is created to add to each of the nine samples with its following stock ingredients: 10 ul of 2X Reaction Buffer, 1 ul of Nco1, X ul of sterile water (Single digest), 10 ul of 2X Reaction Buffer, 10 ul plasmid DNA, 1 ul Nco1, 1 ul of Not1, and X ul of sterile water (Double