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Topic: Transforming principle

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In the News (Thu 20 Jun 19)

 Transforming principle definition - Medical Dictionary definitions of popular medical terms
Proteases -- enzymes that deactivate proteins -- and lipases -- enzymes which destroy lipids -- were found not to inactivate the transforming principle.
Further, the transforming substance had a high molecular weight, as did DNA, and gave a strong reaction to the Dische test for DNA.
If the results of the present study on the chemical nature of the transforming principle are confirmed, then nucleic acids must be regarded as possessing biological specificity...."
www.medterms.com /script/main/art.asp?articlekey=24824   (385 words)

  genome.gov | ONLINE Education Kit - 1944
The bacteriologists were interested in the difference between two strains of Streptococci that Frederick Griffith had identified in 1923: one, the S (smooth) strain, has a polysaccharide coat and produces smooth, shiny colonies on a lab plate; the other, the R (rough) strain, lacks the coat and produces colonies that look rough and irregular.
The transforming principle could be precipitated with alcohol, which showed that it was not a carbohydrate like the polysaccharide coat itself.
They found that the transforming substance was rich in nucleic acids, but ribonuclease, which digests RNA, did not inactivate the substance.
www.genome.gov /Pages/Education/Kit/main.cfm?pageid=28   (348 words)

 Transformation (genetics) Summary
Transformation may be either a natural process—that is, one that has evolved in certain bacteria—or it may be an artificial process whereby the recipient cells are forced to take up DNA by a physical, chemical, or enzymatic treatment.
Griffith was not able to determine the nature of this transforming principle, but his experiments suggested that some "inheritable" material present in the heated extract could genetically convert strains from one colony type to another.
In bacteria the term transformation is not normally applied to genetic changes arising by Transduction or Conjugation, in which transfer of DNA is mediated by genetic parasites (phages and conjugative plasmids respectively).
www.bookrags.com /Transformation_(genetics)   (3588 words)

 A gene is made of DNA.
This so-called "transforming principle" appeared to be a gene.
The principle transformed the R into the infective S strain with a smooth coat.
Since the transforming principle was not the sugar coat, and not protein, we suspected that it may be one of the nucleic acids.
www.dnaftb.org /dnaftb/text/17/index.html   (2359 words)

 Transforming principle definition - Medical Dictionary definitions of popular medical terms
It was definitely not a carbohydrate like the polysaccharide capsular material, as carbohydrates are not precipitated by alcohol, as was the "transforming principle." Alcohol was, however, a well-known precipitant for deoxyribonucleic acid (DNA).
The transforming substance, which produced permanent, heritable change in an organism, was deoxyribonucleic acid.
Avery, MacLeod, and McCarty published their discovery that the transforming principle was DNA in 1944 in the Journal of Experimental Medicine.
www.medicinenet.com /script/main/art.asp?ArticleKey=24824   (396 words)

 Transforming the criminal justice system
The private and public sectors have been transformed over the past 10-20 years by a move away from uniformity of treatment to a differentiated approach in which individuals with different needs are treated differently - and, as a result, organisations have been able to enjoy big gains in efficiency, effectiveness and service quality.
The second principle - moving from a passive stance by the state in relation to persistent and potential offenders to an active stance, in which 'at risk' individuals receive much more attention and support to address their propensity to commit crime.
This principle takes as its starting point the fact that something like 100,000 persistent offenders commit half of all crime, but only 20,000 of these are in prison at any give time.
www.ey.com /GLOBAL/content.nsf/UK/Government_Services_-_Library_-_Transforming_the_criminal_justice_system   (1279 words)

 Untitled   (Site not responding. Last check: 2007-10-30)
Hardy-Weinberg principle--- bionomial expression used to predict the genotype frequencies expected with a randomly mating.
Transformation--- process of transforming a cell from one type to another.
Transforming principle--- an unknown factor, later found to be DNA, that was able to transform nonvirulent strains of Pneumococcus bacteria into virulent forms.
genetics.biol.ttu.edu /genetics/glossary.html   (3908 words)

 Biology 161 Molecular Basis of Inheritance
Griffiths showed that something (he called it the transforming principle) was released by dead, virulent, smooth-coated bacterial cells.
When the transforming principle was treated with DNAse, it failed to transform the rough bacteria.
The conclusion: that DNA was the transforming principle.
www.nsci.plu.edu /~mivey/1612000/chp16.htm   (1516 words)

 Griffith's experiment - Wikipedia, the free encyclopedia
Griffith's experiment was conducted in 1928 by Frederick Griffith which was one of the first experiments suggesting that bacteria are capable of transferring genetic information, otherwise known as the “transforming principle”, which was later discovered to be DNA.
It had been transformed into the lethal S strain, obviously by a transforming principle that was somehow part of the dead S strain bacteria.
Since the IIR strain does not mutate into the IIIS strain, this suggested to Griffith that some of the "transforming principle", which we now know to be DNA, was transmitted from the heat killed IIIS strain to the living IIR strain.
en.wikipedia.org /wiki/Transforming_principle   (412 words)

 Frederick Griffith - Wikipedia, the free encyclopedia
In what is today known as Griffith's experiment, he discovered a transforming principle, which is today known as DNA.
The bacteria isolated from the mice infected with the mixture of live R and heat inactived S were all of the S strain, and maintained this phenotype over many generations.
Griffith hypothesized that some "transforming principle" from the heat inactivated S strain converted the R strain to the virulent S strain.
en.wikipedia.org /wiki/Frederick_Griffith   (315 words)

 The Oswald T. Avery Collection: After the Discovery: The Transforming Principle's Reception by the Scientific Community
Many of the scientists who had previously thought that genetic material was protein still believed that the effects of the transforming principle were perhaps due to some undetected protein associated with the DNA.
One of Avery's colleagues, Alfred E. Mirsky, himself a noted figure in biochemical genetics, was certain that the active component of the transforming substance was a protein associated with nucleic acids in the chromosomes of some higher organisms.
The work which began with Avery's identification of DNA as the "transforming principle" thus led to research that overturned the old conception of DNA as a repetitive and simple molecule, confirmed DNA's role in genetic transmission, and, with James Watson and Francis Crick's 1953 paper, elucidated its structure with its genetic implications.
profiles.nlm.nih.gov /CC/Views/Exhibit/narrative/after.html   (902 words)

 The Oswald T. Avery Collection: DNA as the "Stuff of Genes": The Discovery of the Transforming Principle, ...
After achieving reliable and long-lasting transformation, Avery turned to prove that it was caused by DNA alone, despite the prevailing conviction of most geneticists, and even his own earlier belief, that DNA was a simple molecule and that genes must be composed of protein, a seemingly more complex substance.
As Avery and McCarty turned their attention to the chemical analysis of transformation, they found that proteases (enzymes that deactivate proteins) and lipases (enzymes that destroy lipids) did not inactivate the transforming principle, and thus concluded that the substance was essentially protein- and lipid-free.
If the results of the present study on the chemical nature of the transforming principle are confirmed, then nucleic acids must be regarded as possessing biological specificity." Their findings were accepted almost immediately by some, but for several years they would be the source of considerable debate among genetic researchers.
www.profiles.nlm.nih.gov /CC/Views/Exhibit/narrative/dna.html   (917 words)

 Transformation   (Site not responding. Last check: 2007-10-30)
Identification of DNA as the transforming principle of pneumococci was a major factor in the realization that hereditary material consisted of nucleic acids.
The ability to transform organisms with extracted DNA is important to the molecular analysis of chromosomes.
The experiments of Avery, MacLeod and MacCarty (3) demonstrated that the transforming principle was not protein or RNA and strongly suggested that it was DNA.
opbs.okstate.edu /~melcher/MG/MGW1/MG11211.html   (248 words)

 DNA . Episode 1 . The Secret of Life . Special Report | PBS
Avery and his colleagues, Colin MacLeod and Maclyn McCarty, went about their quest for the transforming principle in a systematic manner.
They had made it clear that DNA is the transforming principle.
And for years there was a looming suspicion that the DNA that Avery had claimed as the transforming principle had been contaminated by proteins that might have carried the genetic information.
www.pbs.org /wnet/dna/episode1/essay1b.html   (658 words)

 The Scientist : The Transforming Principle
O.T. Avery et al., "Studies on the chemical nature of the substance inducing transformation of pneumococcal types," J Exp Med, 79:137-58, 1944.
But with mechanisms I am not now concerned--One step at a time--and the first is what is the chemical nature of the transforming principle?
It touches the biochemistry of the thymus type of nucleic acids which are known to constitute the major part of the chromosomes but have been thought to be alike regardless of origin and species.
www.the-scientist.com /article/display/13972   (277 words)

Fredrick Griffith’s pioneering work on the transforming principle, in 1928, was extended by Oswald T. Avery, Colin M. MacLeod and Maclyn J. McCarty.
The transforming principle had the capacity to transform avirulent bacteria to a virulent form, to alter the phenotype of the organism.
Transformants passed the trait to successive generations, suggesting that the phenotypic transformation involved a change in genotype, a change that was inheritable.
anirvan_c.tripod.com /chapter/chapter12.htm   (330 words)

He experimented further and found that the information specifying the polysaccharide coat could be passed from dead, virulent bacteria to coatless, nonvirulent strains.
Avery's experiments with the transforming principle from Griffith's experiments demonstrated conclusively that DNA is the hereditary material.
What Avery found was that the purified transforming principle had the same chemistry as DNA, it behaved similarly to DNA, it was not affected by lipid or protein extraction, it was not destroyed by protein- or RNA-digesting enzymes, but it was destroyed by DNA-digesting enzymes.
homepage.mac.com /ugokido/pcom/Biology/Chapters/Chapter8.html   (1645 words)

 Extracting Plasmid DNA   (Site not responding. Last check: 2007-10-30)
But if you were to obtain ampicillin-resistant transformants from a DNA/RNA mixture that had been digested with DNase to degrade the DNA, it would be a good indication that the RNA was actually the transforming principle.
You can not transform bacteria with RNA (as far as I know), even if you were able to get the RNA in the cell, it could not replicate (unless it is an RNA virus) nor could it recombine into the DNA of the cell.
So, if you attempted to transform with RNA, you would run into (at least) one major problem: How to have the RNA get changed back into DNA so it could replicate and be present in all the succeeding generations.
www.newton.dep.anl.gov /askasci/mole00/mole00252.htm   (524 words)

It showed that DNA possessed genetic information that could transform the heritable character of cells, but the world of biological research in 1944 had enough in the way of distractions, assumptions, and divisions to withhold its attention from such a revolutionary idea.
Griffith had attempted to demonstrate the transforming effect in vitro but had failed; Dawson saw an opportunity and succeeded with Richard Sia in recapitulating in vitro the virulence switching he'd seen in mice.
7) Despite growing evidence equating DNA with the transforming principle, it wasn't until the early '40s that the group recognized that the shiny precipitate they'd been observing in their active preparations might itself be DNA, and not polysaccharide contaminant as they had once assumed.
scienceweek.com /2004/sa041001-6.htm   (1881 words)

 Spartanburg SC | GoUpstate.com | Spartanburg Herald-Journal   (Site not responding. Last check: 2007-10-30)
Griffith's experiment, conducted in 1928 by Frederick Griffith, was one of the first experiments suggesting that bacteria are capable of transferring genetic information though a process known as transformation.
Griffith concluded that the type II-R had been "transformed" into the lethal III-S strain by a "transforming principle" that was somehow part of the dead III-S strain bacteria.
Today, we know that the "transforming principle" Griffith observed was the DNA of the III-S strain bacteria.
www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=transforming_principle   (271 words)

 Frederick Griffith Summary
They extracted the active transforming principle from Type III (S) pneumococcus and showed preliminarily that it was DNA.
Although interesting enough for the light it shed on the virulence of certain organisms, what he called the "transforming principle" was also the first clear evidence linking DNA to heredity in cells.
In what is today known as Griffith's experiment, he discovered a transforming principle, which is today known as DNA.
www.bookrags.com /Frederick_Griffith   (1755 words)

 The Search for the Genetic Material   (Site not responding. Last check: 2007-10-30)
What transforming principle was the dead virulent strain giving to the avirulent strain to make it lethal?
Avery and his colleagues separated the dead virulent cells into fractions and coinjected them with the avirulent strain, to see which fraction contained the transforming principle.
Most scientists at the time, in favour of the theory of protein as genetic material, discounted this result and said that there must have been some protein in the fraction that conferred virulence.
jan.ucc.nau.edu /~fpm/bio205/lect14.html   (409 words)

 DNA as the Genetic Material   (Site not responding. Last check: 2007-10-30)
Transformation II Oswald Avery, Colin MacLeod, Maclyn McCarty
They concluded that since DNase treatment destroyed both the DNA and the ability to transform, the DNA must be the transforming principle.
He transformed a penicillin sensitive strain to resistance.
www.rhodes.edu /biology/glindquester/molbiol/mbprotected/genetmat.html   (612 words)

 Griffith's Experiment
What was going on was DNA from the heat killed smoothe bacteria (encoding the genes for synthesizing the polysaccharide coat) was taken up by the live rough bacteria and incorporated into their "chromosome" thus conferring upon them the property of virulence (synthesis of the polysaccharide coat).
When he purified the active ingredient (transforming principle) from the smoothe bacteria, he found that this transforming principle was not inactivated by proteases (enzymes that degrade protein) but that it was destroyed by DNAase (an enzyme that degrades DNA).
The logical conclusion then was that the transforming principle (or genetic material) was DNA.
www.newton.dep.anl.gov /askasci/mole00/mole00545.htm   (553 words)

 The Scientist : Maclyn McCarty dies
Colleagues agreed it was McCarty's meticulous work and strong skills in biochemistry that helped bring Oswald T. Avery's 13-year effort to identify the "transforming principle" to a convincing conclusion.
Avery, who had been working on pneumococcus at the Rockefeller Institute for Medical Research since 1913, began searching for what he called the "transforming principle" in 1931, after being alerted to the problem by Fred Griffith's 1927 report that mice injected with a mix of heat-killed, deadly pneumococcus and a live harmless strain would die.
By the summer of 1942, McCarty recounted in his 1985 memoir, The Transforming Principle, the convergence of several lines of research on DNA had "pretty much convinced us that in all probability it was the transforming substance." But several more months of experiments would follow until the team felt prepared to write up its research.
www.the-scientist.com /news/20050110/01   (727 words)

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