Description of Agrobacterium Tumefaciens Essay

The first result of importance was the result of the Gram stain. The observations of the unknown bacteria from the slant culture after Gram staining showed that the unknown bacteria were Gram negative bacilli (Image 1). After determining the unknown bacteria was Gram negative, an oxidase test was conducted on a sample from the slant culture. The cotton swap with the sample of bacteria did not change color when the oxidase reagent was applied, thus providing a negative result. With a negative oxidase test, further tests were conducted to determine various characteristics of the unknown bacteria. A MR-VP broth was inoculated with a sample from a slant culture of unknown bacteria. After incubation, the methyl red reagent was added to the broth, and the broth turned red, providing a positive result (Image 2). An EMB agar streak plate was inoculated with a sample from a slant culture of the unknown bacteria, and after incubation, growth was found on the plate, providing a positive result (Image 3). A Citrate agar slant was inoculated, and after incubation, growth was found on the media, providing a positive result (Image 4). A Urea agar slant was inoculated, and after incubation, the agar had changed from a peach color to a bright pink color, providing a positive result (Image 5). Using the flowchart (Figure 1) developed from the Table of Expected Results, the lab partners started at the oxidase test. Given the negative result of the oxidase test, the flowchart is

The field of biotechnology has continued to grow due to the advancements in genomic technology and development of genetically modified organisms. The ability to amplify certain genes and place them into another organism gives off a “Frankenstein” feeling. The gene swapping that takes place naturally is a survival mechanism that allows bacteria to adapt and develop (Biello 2005). Using these bacterial or viral parasites to exchange genetic information can insert genes that can cause adverse effects when in the new

There were two tubes used in this process: the tube that contained the primary culture and the tube that contained the nutrient agar where the unknown bacteria would grow. First, the inoculating loop was flamed. After removing the caps of both the test tubes, they were flamed to prevent contamination of the unknown bacteria. The inoculating loop was cooled for a few seconds and was then placed into the test tube containing the bacteria. The inoculating loop with the bacteria was placed into the nutrient agar test tube for cultivation. Before the test tubes were capped, they were flamed once again. Also, isolation of the unknown bacteria had to completed. Nutrient agar was placed in the petri dish, and was left to gel for a few minutes. After the agar gelled, the inoculating loop was used to acquire bacteria and streak the unknown onto the plate for

Stanley N. Cohen is perhaps one the few men who have had to greatly influence America. Mr. Cohen is an American biochemist who alongside Herbert Boyer “…led to the development of methods to combine and transplant genes…”, the beginning of bio engineering, and would eventually become the first to create a genetically modified organism. This man and his team began the first GMOs in 1972 with bacteria. Cohen and Boyer found that DNA could be changed within bacteria using enzymes to “…counter invasion by viral organism…” that would harm bacteria. This demonstrated “…that these genes were active…” after insertion and could be passed on when bacteria replicated.

In order for a person to make a smart logical decision regarding a pro or anti-GMO position one must understand what a GMO is. A plant that is genetically modified and then the Deoxyribonucleic acid (DNA) of one plant is forced into another kind of plant to be considered a GMO. This process takes place in a laboratory. It is not limited to just plants. Animals can also be modified. Viruses, insects, bacteria, humans, and animals can all supply the foreign DNA. Some researchers also refer to the process as Genetic Engineering(GE) (10 Reasons”).

Starting around “the 1920s, scientists theorize[d] that DNA carried genetic information” and about half a decade later, altering of DNA began (Genetic Engineering, Opposing Viewpoints). Today genetic engineering in agriculture booms as it provides us with year-round access to

METHODS/PROCEDURES: In the beginning of the experiment, pea seeds were used in order to perform the experiment. It was extremely important to acquire good, dry, and viable seeds so the process of germination could occur. A handful of these healthy seeds worked best in assisting the experiment. The seeds ability to germinate was a vital information needed to determine the outcome of the experiment.

The idea of changing natural processes to produce an “ideal” crop raises concern amongst environmentalists. Extracting bacteria from soil and inserting it into an entirely different species may appear unethical because of the changing of natural processes. Genetic engineering promotes producing a type of crop that is not susceptible to pests, but carries the risk of decreasing genetic variation (Green Peace). Once a crop is perfected, farmers then mass produce that specific crop, and the different variations of the crop are lost (Green Peace). Another concern regarding the use of the Bt protein is the increased risk of allergies (Smith). The transgenic protein comes from bacteria in the soil, and thus raises the concern of allergic reactions to the corn. Consumers are worried that the cry protein injected into Bt corn could have allergies unknown to them because of the cry protein’s characteristic of an extended digestion time. Consumers are also skeptical that genes of this antibiotic resistance could somehow be introduced to other bacteria in the soil, and possibly infect consumers with this bacteria. A major ethical concern of genetically modified crops, specifically Bt corn, is the lack of knowledge of the long term effects these crops have on humans and other organisms. Consumers are uninformed about the

These chemical signals set off a cascade of gene activity in the A. tumefaciens which direct a series of events required for the transfer of tDNA from the plasmid into the plant’s cells through the wounds of the plant. The tDNA then moves into the nucleus of the plant cell and becomes integrated into the plant chromosome (Understanding GMOs).

One of the prominent men behind the germ theory was Robert Koch, a German physician, who laid the foundation for the theory. Koch experimented on animals because he noticed what most people saw as a mystery. He used a microscope to look at blood that belonged to cows that died of anthrax. Koch discovered that there were tiny bacteria shaped like a rod and supposed that it was a disease called anthrax. Out of curiosity, he transported the bacteria to mice, which also acquired anthrax. His observation of the transportation of anthrax led Koch to create the four standards that determines that a certain germ can cause a specific disease. Koch’s criterion famously known as Koch’s Postulates and are still commonly used. His third postulate is, “the disease must be reproduced when a pure culture is inoculated into a healthy, susceptible host.” In other words, a disease is able to multiply when a clean group of germs introduces itself to a vulnerable animal to house the germs. Robert Koch launched the germ theory for other great minds to enhance by discovering a disease and creating a set of principles.

Another purpose of this experiment is to stress the importance of knowing the identity of a microorganism. Knowing the species of microorganism present in a sample provides a

Instead of transferring large blocks of genes from donor plant to recipient, small isolated blocks of genes are put into the plant chromosome through biolistics, vectors, or protoplast transformation (Horsch 1993). Biolistics is a technique that shoots the gene block into the potential host cell. In order for the process to succeed, the microscopic particles and DNA must enter the cell nuclei and combine with the plant chromosome. Biolistics is commonly used but has a slight failure risk since the breeder has little control over the destination of the gene block (Mooney & Bernardi 1990). Bacteria or viruses can also carry the gene blocks into a new cell. Common vectors in gene transfer between plants are Agrobacterium tumefaciens and Agrobacterium rhizogenes. In the soil, the bacteria will infect the plants with their own plasmid, transferring the desired gene that was placed in the bacteria's DNA. Vector gene transfer is a preferred method of transformation since this modification already occurs naturally in the environment (Rudolph & McIntire 1996). Last is protoplast transformation, which uses enzymes to dissolve the cellulose in the plant wall that leaves a protoplast. Once a specific gene block is added to the protoplast, the cell wall will re-grow into a transgenic plant.

Answer #1: Koch was the major mind in establishing that microorganisms cause a specific disease. He was able to prove that certain bacteria was present in the blood of the infected person or animal, but the presence of the bacteria could have been caused by the disease. Koch proved that certain infectious diseases are caused by certain microorganisms that can be isolated and cultures onto a media. The requirements Koch established are that the same pathogen must be present in every case of the disease, the

The coding region of the gene is usually fused to a promoter, most commonly used is the 35S promoter from cauliflower mosaic virus (CMV), in order to promote higher expression levels. (Snow et. al, 1997) The popular method for genetic engineering of crop plants is natural gene transfer via an Agrobacterium tumefaciens vector, a bacterium normally found in soils. The transfer-DNA (T-DNA) vector is made by inserting the desired gene fragment in between specific 25bp repeat domains in the bacterium. The vector is then inserted into the Agrobacterium and "the virulence gene products of Agrobacterium actively recognize, excise, transport, and integrate the T-DNA region into the host plant genomes." (Conner et. al, 1999) The amount of DNA transferred is only about 10kb and the nature of the gene is usually well understood. The expression of the gene introduced can also be controlled by adding additional sequences that might allow the gene to be constitutively expressed, expressed only in certain cell types, or expressed as a result of different environmental changes. This method of gene transfer, however, will only work for the natural host range of the bacterium and therefore other methods are used for additional crop plants. Such methods are uptake of naked DNA by electroporation or particle gun bombardment. The use of genetic markers, as mentioned previously, allows for the preferential growth of cultures that contain the new genetic

Culturing Agrobacterium tumefaciens has been essential in discovering the full mechanisms of its infection and tumor formation. Moreover, A. tumefaciens can be isolated from multiple sources including water, soil, and the gall of infected plants