Then the cells were treated with Na-deoxycholate (a detergent to lyse cells and solubilise cellular and membrane components) followed by protein removal using chloroform and hydrolysing capsular polysaccharide using enzymes. The alcohol fractionation was done to extract the transforming principle in form of fibrous precipitation.
Full Answer
How did the scientist conduct his experiments with rats?
He conducted his experiments by placing rats into buckets filled with water and seeing how long they survived. He introduced a range of variables into the experiment, that yielded some interested results.
What is the drowning rats psychology experiment?
In the 1950s, Curt Richter, a professor at Johns Hopkins, did a famous drowning rats psychology experiment. This experiment, though cruel, demonstrated the power of hope and resilience in overcoming difficult situations. Summary by The World of Work Project A Psychology Experiment: Drowning Rats
What did the Rat Park experiment show about addiction?
This “Rat Park” experiment culminated in the leading breakthrough of the time: the underlying connection between a person’s environment and addiction. The Rat Park Experiment aimed to prove that psychology – a person’s mental, emotional, and psychosocial states – was the greatest cause of addiction, not the drug itself.
What did Avery and Avery et al study?
( Just for info: Have a look at the o riginal paper published by Avery et al. In 1944) They carried out series of experiments and studied various parameters of the purified material. They studied the general properties like solubility, storage and effect of heating.
What happened in Avery's experiment?
In a very simple experiment, Oswald Avery's group showed that DNA was the "transforming principle." When isolated from one strain of bacteria, DNA was able to transform another strain and confer characteristics onto that second strain. DNA was carrying hereditary information.
What was the conclusion from Avery's experiment?
Avery concluded that DNA is the genetic material of the cell. As the experiments of Griffith and Avery illustrate, science is a process in which discoveries often build upon the results of previous experiments. Despite Avery's findings, many scientists remained skeptical that genes were made of DNA rather than protein.
What was the purpose of treating the extract with protein degrading enzymes in the Avery MacLeod McCarty experiment?
91. What was the purpose of treating the extract with protein-degrading enzymes in Procedure II ? In the 1940's, Avery, MacCleod, and McCarty transformed nonencapsulated bacteria into encapsulated forms by growing the nonencapsulated cells in a culture containing an extract made from dead encapsulated cells.
What is the best explanation why the mice died when injected with a mixture of live cells from the harmless strain and heat-killed cells from the disease causing strain?
Heat-killed smooth strain. When heat-killed smooth cells are injected into a mouse, the mouse lives. Rough strain & heat-killed smooth strain. When these two types of cells are injected into a mouse as a mixture, the mouse gets pneumonia and dies.
What did Avery do?
Avery was one of the first molecular biologists and a pioneer in immunochemistry, but he is best known for the experiment (published in 1944 with his co-workers Colin MacLeod and Maclyn McCarty) that isolated DNA as the material of which genes and chromosomes are made.
What was the purpose of Oswald Avery's experiments?
What was the purpose of Oswald Avery's experiments? He built upon Griffiths experiments to determine what was the transforming factor (DNA or protein).
What enzymes were used in Avery's experiment?
They found that trypsin, chymotrypsin and ribonuclease (enzymes that break apart proteins or RNA) did not affect it, but an enzyme preparation of "deoxyribonucleodepolymerase" (a crude preparation, obtainable from a number of animal sources, that could break down DNA) destroyed the extract's transforming power.
What was the result of Avery and MacLeod experiment?
Oswald Avery, Colin MacLeod, and Maclyn McCarty showed that DNA (not proteins) can transform the properties of cells, clarifying the chemical nature of genes. Avery, MacLeod and McCarty identified DNA as the "transforming principle" while studying Streptococcus pneumoniae, bacteria that can cause pneumonia.
What result did Avery MacLeod and McCarty obtain in their experiments with virulent bacteria?
What results did Avery, McLeod, and McCarty obtain in their experiments with virulent bacteria? DNase destroyed the transforming activity.
What happened when the mice were injected with a mix of dead S strain and live R strain?
In the critical experiment, Frederick Griffith (1928) mixed heat-killed S with live R and injected the combination into mice: the mouse died. The dead mouse's tissues were found to contain live bacteria with smooth coats like S.
What did Avery conclude caused transformation?
What did Avery conclude caused transformation? DNA was the transforming factor.
Why do you think that the mix of bacteria killed the fourth mouse?
Because the heat-killed bacteria mixed with the rough bacteria were lethal to the mouse, Griffith concluded that something from the heat-killed bacteria “transformed” the rough bacteria and made them lethal.
What did the researchers do in the Rat Park experiment?
The researchers dubbed their new experiment the Rat Park experiment and introduced wild rats to the rat park to interact with the lab rats. Both the caged rats and the rats in the park had access to morphine.
What drug do rats take when they press the lever?
When they pressed the lever, the rats would give themselves a dose of psychoactive drugs. In nearly all of the cases, the drug in question was heroin. Heroin is one of the most addictive drugs of all time. The point was that every time a rat moved the lever, they got an immediate dose of the drug.
What was the purpose of the Skinner Boxes experiment?
They also used something called Skinner boxes, which were cages designed with electrical devices that could either reward the rats with food or punish them with electric shocks . These cages allowed scientists and behavioral psychologists to study behavior. The Rat Park experiment broke away from this paradigm.
What kind of rats were in the rat park?
All of the rats in the experiment were albino, descendant from a breed of Norwegian rats. This is a sociable, curious, and intelligent species. Being isolated in cages was obviously not their natural habitat. With all that in mind, these new researchers came up with the idea to create a rat park. Alexander wondered if “free” rats would behave ...
Why do rats push the lever?
The researchers noticed that, in certain circumstances, some of the rats pushed the lever repeatedly, supplying themselves with large quantities of the drug. Some of the rats became so intoxicated that they forgot to eat or drink.
Why are rats used in the Rat Pack?
The famous Rat Park experiment offered some fascinating insights into the nature of addiction. Rats are often used for “psychological experiments” due to their genetic similarity to humans. Ninety-five percent of the human genome is identical to that ...
What did behavioral psychologists do in the 60s?
What the behavioral psychologists of the 60s did was surgically place a supply device inside the rats. Then, they put them in Skinner boxes (individual cages). After that, they taught them to press the lever in the cage. When they pressed the lever, the rats would give themselves a dose of psychoactive drugs.
What was the Rat Park experiment?
At its time of publication, the Rat Park Experiment argued what was not a popular theory. Scientists had for years “proved” that substances themselves caused an addiction, an idea that anti-drug campaigns and companies took and ran with. Many experts refuted the Rat Park theory, even after subsequent studies came to the same conclusions. Simon Fraser University shut down the experiment, and for a while, it was more or less forgotten.
What was Alexander's goal in the Rat Park experiment?
Details Of The Rat Park Study. The goal of Alexander’s Experiment was to prove that drugs do not cause addiction, but that a person’s living condition does. He wanted to refute other studies that connected opiate addiction in laboratory rats to addictive properties within the drug itself.
How do rats drink water?
In the experiment, the social rats had the choice to drink fluids from one of two dispensers. One had plain tap water, and the other had a morphine solution. The scientists ran a variety of experiments to test the rats’ willingness to consume the morphine solution compared to rats in solitary confinement. They found that: 1 The caged rats ingested much larger doses of the morphine solution – about 19 times more than Rat Park rats in one of the experiments. 2 The Rat Park rats consistently resisted the morphine water, preferring plain water. 3 Even rats in cages that were fed nothing but morphine water for 57 days chose plain water when moved to Rat Park, voluntarily going through withdrawal. 4 No matter what they tried, Alexander and his team produced nothing that resembled addiction in rats that were housed in Rat Park.
How do rats inject drugs?
The rats could choose to inject themselves with the drug by pushing a lever in the cage. Scientists studied drug addiction this way, using heroin, amphetamine, morphine, and cocaine. Typically, the rats would press the lever often enough to consume large doses of the drugs. The studies thus concluded that the drugs were irresistibly addicting by ...
What was the main breakthrough of the rat park?
This “Rat Park” experiment culminated in the leading breakthrough of the time: the underlying connection between a person’s environment and addiction.
Do rats drive people insane?
However, rats by nature are social, industrious creatures that thrive on contact and communication with other rats. Putting a rat in solitary confinement does the same thing as to a human, it drives them insane.
Do caged rats eat morphine?
They found that: The caged rats ingested much larger doses of the morphine solution – about 19 times more than Rat Park rats in one of the experiments. The Rat Park rats consistently resisted the morphine water, preferring plain water.
Pitfalls with Previous Rat-Based Studies on Drug Addiction
Details of The Rat Park Study
Psychology and Drug Addictions
How Rat Park Affects Treatments Today
