Frederick Griffith conducted one of the first experiments showing bacteria can get DNA by a process called “transformation.” He used two types of bacteria that infect mice-- S strain and R strain. The S strain covers itself with a polysaccharide capsule that protects it from the host's immune system, causing the mice to dice. The R strain does not have that protective shield around it and is killed by the host's immune system. The S strain was heated to kill it, and then injected into mice, it produced no bad effects. But, when dead S strain mixed with live R strain was injected into the mouse, the mouse died. the combination of the two was able to kill it. He concluded that the R strain had been "transformed" into the S strain by a "transforming …show more content…
There were three hypotheses suggested: dispersive, conservative, and semiconservative. The first possibility is conservative replication; one daughter cell consists of the two original strands and the other daughter DNA consists of two newly synthesized chains. The second possibility is semiconservative replication; both daughter cells contain one original and one newly synthesized strand of DNA. The last possibility is dispersive replication; suggesting the random placement of parental and new segments in daughter DNA molecules. Meselson and Stahl thought the replication mechanisms could be distinguished easier if parent and daughter cells were labeled differently. They achieved that by changing the molecules so each kind had a different density. Meselson and Stahl included non-radioactive isotopes of nitrogen with different weights into the DNA of E. coli. As heavy nitrogen bacteria grew, they duplicate, replicating their DNA in the process. The researchers added light nitrogen to the heavy nitrogen environment. Using ultraviolet light, the researchers photographed the resulting DNA bands.The result showed that the half heavy nitrogen and half light nitrogen DNA band had a density exactly between the two DNA. The exact split between heavy and light nitrogen characterized semiconservative DNA
Use a test tube holder to put the test tube into a container of boiling water for 5 minutes, or until the solution changes color.
After precisely conducting the experiment and tabulating the results, data for Paraquat toxicity upon P. vulgaris plants can be interpreted over several different parameters. The parameters by which Paraquat toxicity was examined within this experiment involve visual observations, x-ray diffraction, chlorophyll concentrations, protein concentrations, and lastly malondialdehyde (MDA) concentrations on a per mg of protein basis. As stated before Paraquat is very widely used herbicide known to produce superoxide anions leading to chloroplast membrane damage and ultimately a variety of adverse effects upon the host organism, in this case P. vulgaris (Chia et al., 1982).
The oxidation number of an atom of any free element is ZERO. Means to say there is only one kind of atom present, no charge.
Citrobacter Freundii is a species of bacteria that can be potentially harmful to humans. It is known to cause meningitis by protruding into the brain and replicating itself (1). The Citrobacter species has also been found as a cause of some urinary tract infections, diarrhea, and even gastrointestinal diseases and symptoms (3). C. Freundii can be located in a wide variety of soils and water (3). Lastly, it is also the cause of many nosocomial infections due to its presence in water (1).
Transformation is the transfers of virulence from one cell to another, through the transferring of genetic material. It was originally postulated in 1928 through the works of Federick Griffith, a British microbiologist. Griffith observed that the mutant form, non-virulent form, of the bacteria Streptococcus Pnumoniae could be transformed into the normal, virulent form, when injected into mice along with heat killed normal forms. He concluded that somehow the information the dead virulent form had transformed the mutant form into a virulent form.
When looking over my results, I found that the pH level increased from a neutral pH to a basic level of pH. The Miracle- Gro fertilizer that I used is supposed to have a pH of 7. This surprised me because I would think that adding a 10% fertilizer solution would make the water acidic. I thought that the fertilizer would be more acidic because when we learned about rivers, we found out that acid rain decreased the dissolved oxygen levels; also, Eutriporication results in low dissolved oxygen levels. Therefore I believed that the fertilizer would be acidic because of my background knowledge of dissolved oxygen in water. Regardless, the basic water killed the algae, elodea plant and the snails in the water. I also thought that eutrophication would occur in the water when
With bacteria as the focus of the passage beginning on page 209, the stage is set for its/their inner workings and that while only a small percentage there is harmful or destructive bacteria present in and on the human body. It is addressed on page 236 that the Andromeda Strain in particular reacts and multiplies more rapidly when provoked. I believe, in this section of text, Crichton is reflecting on how post-World War II, the United States develops the baby boomer generation, where like bacterial colonies, the American population increases dramatically. As previously mentioned, some of these bacteria are destructive, and detrimental to the human body, similar to how the United States was beginning to become to the rest of the world. As the
One major theme of The Andromeda Strain is how intelligence of man can lead to his downfall. In the novel, the United States government had come up with the technology to put man made devices into Earth's orbit to collect data on outer space. This demonstrates man's great intelligence, but ultimately the new technology leads to an unprecedented crisis. On the other hand, this intelligence of man can also be interpreted as ignorance. While the team of scientists in the novel were of the most intelligent people in the world, when it came to the Andromeda Strain, they were just as ignorant as any other person. That is, until they began researching it, but ultimately, the Andromeda strain was in control. This is because humans had never experienced
In 1928, Fred Griffith first discovered genetic transformation by infecting mice with unencapsulated and non-pathogenic pneumococci (Lacks 2003). This was the start that opened up the field of biotechnology. Genetic transformation is a process where foreign DNA crosses a membrane of another cell and then alters the genetic material (Encyclopædia Britannica 2015). Genetic transformation can occur in a few different ways: projectile bombardment, electroporation, and heat shock (Weedman 2015). Heat shock is defined by increasing the temperature of cells environment making the plasma membrane become more permeability allowing new DNA to transfer into the cell (Weedman 2015). The cell receiving the new DNA, also known as competent cells, can either amplify the DNA or clone the DNA (JoVE 2015). The most common type of DNA used to perform genetic transformations is plasmids: small, round DNA molecules that still contains two strands of DNA that has the ability
2. During Griffith’s experiments, he injected mice with strains of pneumococcus The rough (R) strain bacteria are not virulent, but smooth (S) strains are meaning they killed the mice. When he injected a live R strain with no capsule into the mice, the mice survived. Griffith then injected heat-killed S strain into the mice and they also survived. Later, he injected heat-killed S strain and live R strain into the mice and, surprisingly, they died. Griffith withdrew live S strain from the dead mice. He concluded that a passing by substance transformed the R strain from the dead S strain into the live R strain.
In the world of microbiology it is vitally important to be able to discern the identities of microorganisms. Not only is it important in a lab setting but as well as in healthcare in general. Properly identify what strain of bacteria a person has will aid in the proper medicine and dose given. Throughout the semester we have learned about different types of bacteria and certain test that can clearly identify them. The purpose of this lab report is to identify a Gram-positive or Gram-negative bacterium. Using all the knowledge of procedures and lab techniques identify the unknown and discuss all the tests you performed.
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
In this essay, we will observe the structure of DNA, DNA replication and how scientist visualizes DNA. First off, DNA or deoxyribonucleic acid, resides in the nucleus of every living cell. DNA structure was understood more by Rosalind Franklin with the help of other biologists later on during the year, to describe the twisted ladder or double helix structure of DNA. It must go through a complex task called DNA replication to duplicate itself to form two identical DNA molecules. However, for us to visualize DNA with a naked eye, biologists use modern laboratory techniques that allow them to extract DNA from tissue samples.
DNA replication is described as semi-conservative. It is semi-conservative because the replication of one helix results in two daughter helices each of which contains one of the original parental helical strands. Furthermore, it is semi-conservative because the two new daughter DNA molecules are “half old” and “half new”; this means that half the original DNA molecule is saved, or conserved in the daughter DNA molecules.
The process of DNA replication plays a crucial role in providing genetic continuity from one generation to the next. Knowledge of the structure of DNA began with the discovery of nucleic acids in 1869. In 1952, an accurate model of the DNA molecule was presented, thanks to the work of Rosalind Franklin, James Watson, and Francis Crick. To reproduce, a cell must copy and transmit its genetic information (DNA) to all of its progeny. To do so, DNA replicates following the process of semi-conservative replication. Two strands of DNA are obtained from one, having produced two daughter molecules that are identical to one another and to the parent molecule. This essay reviews the three stages