Biology on DNA and Griffith's Transformation
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Questions and Answers

What phenomenon did Frederick Griffith discover during his research?

  • Replicative learning
  • Transcription
  • Transformation (correct)
  • Translocation

How did Griffith classify the virulent strain of Streptococcus pneumoniae?

  • P for pathogenic
  • L for lethal
  • V for virulent
  • S for smooth (correct)

What characteristic of the pathogenic strain of S. pneumoniae contributes to its virulence?

  • Lipid bilayer
  • Deformed shape
  • Protective polysaccharide coat (correct)
  • Ribosomal presence

What term describes the non-virulent strain of S. pneumoniae used by Griffith?

<p>R for rough (D)</p> Signup and view all the answers

What was Griffith's primary goal in studying S. pneumoniae?

<p>To develop a vaccine for pneumonia (A)</p> Signup and view all the answers

How many serotypes of S. pneumoniae have been identified based on their capsular polysaccharides?

<p>Ninety (A)</p> Signup and view all the answers

Which of the following statements is true regarding the smooth strain of S. pneumoniae?

<p>It possesses a protective polysaccharide coat. (C)</p> Signup and view all the answers

In the context of Griffith's experiments, which of the following best describes the term 'transformation'?

<p>The process by which bacteria acquire genetic material from their environment. (D)</p> Signup and view all the answers

What was the result when Dr. Griffith injected live type IIR bacteria into mice?

<p>The mice remained healthy with no bacteria found. (D)</p> Signup and view all the answers

What was observed in mice injected with heat-killed IIIS bacteria?

<p>The mice survived without any symptoms. (B)</p> Signup and view all the answers

What was Griffith's best explanation for the development of pneumonia in mice injected with a mixture of living IIR and heat-killed IIIS bacteria?

<p>The IIIS strain transformed the IIR strain into a pathogenic variant. (B)</p> Signup and view all the answers

What did Griffith observe in the blood of mice that developed pneumonia after injection with the mixed bacteria?

<p>Live type IIIS bacteria were isolated. (C)</p> Signup and view all the answers

Which scenario did Griffith consider to be the least likely explanation for his experimental results?

<p>Poor sterilization of the heat-killed bacteria. (B)</p> Signup and view all the answers

What type of bacteria is the IIR strain classified as?

<p>Non-pathogenic strain. (B)</p> Signup and view all the answers

What role did heat play in Griffith's experiments with the IIIS bacteria?

<p>It killed the pathogenic bacteria. (D)</p> Signup and view all the answers

What did Griffith conclude about the transformation capability of bacteria based on his findings?

<p>Bacteria can genetically alter when exposed to certain conditions. (D)</p> Signup and view all the answers

Flashcards

Transformation (Griffith)

The process in which a non-pathogenic bacteria takes up genetic material from a pathogenic bacteria and becomes pathogenic.

Streptococcus pneumoniae

A type of bacteria that can cause pneumonia.

S Strain

A pathogenic (disease-causing) strain of Streptococcus pneumoniae with a smooth colony.

R Strain

A non-pathogenic (harmless) strain of Streptococcus pneumoniae with a rough colony.

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Capsular Polysaccharides

Protective coats surrounding bacteria that influence their pathogenicity.

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Genetic information carrier

DNA, proven in Griffith experiments, is the entity transmitting genetic properties to new generations.

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Pathogenicity

The ability of an organism to cause disease.

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Frederick Griffith

English physician who conducted experiments demonstrating that bacteria can transfer genetic material from one generation to another

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Griffith's Transformation

Non-pathogenic bacteria acquired genetic material from pathogenic bacteria, becoming pathogenic.

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Type IIIS Bacteria

Pathogenic Streptococcus pneumoniae strain with a smooth capsule.

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Type IIR Bacteria

Non-pathogenic Streptococcus pneumoniae strain with a rough capsule.

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Heat-Killed IIIS

Inactivated IIIS bacteria, unable to cause pneumonia.

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Transformation Experiment

Griffith's experiment showing genetic transfer from one bacteria to another.

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Capsule's Role

Capsules in bacteria determine pathogenicity, either virulent or harmless

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Mutation as Explanation

The proposal that a bacteria changed (mutated) to become pathogenic, but not a direct result of the findings

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Possible Interpretations

Alternatives to transformation as the process behind bacteria's changed behavior

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Study Notes

DNA as the Carrier of Genetic Information

  • Biologists were studying bacterial transformation
  • Frederick Griffith, an English physician, conducted experiments in 1928
  • Griffith studied Streptococcus pneumoniae bacteria
  • Griffith attempted to develop a vaccine against pneumonia
  • He observed a phenomenon called "transformation"
  • He found two strains of S. pneumoniae: virulent (pathogenic) and non-virulent (harmless)
  • Pathogenic strain looked smooth, non-virulent strain looked rough
  • Injecting live pathogenic bacteria into mice caused pneumonia and death
  • Injecting heat-killed pathogenic bacteria into mice did not cause disease
  • Mixing heat-killed pathogenic bacteria with live non-pathogenic bacteria resulted in pneumonia and death in mice
  • Live virulent bacteria were found in the blood of the mice.
  • This suggested that genetic information was transferred from the heat-killed pathogenic bacteria to the live non-pathogenic bacteria.

Transforming Agent

  • Scientists investigated the mechanism behind this transfer.
  • The mixture of killed pathogenic bacteria released substances that could transform non-pathogenic to pathogenic bacteria
  • The mixture contained protein, RNA, DNA, lipids and carbohydrates
  • The question remained - which molecule was the transforming agent?

DNA: The Genetic Material

  • DNA is the primary genetic material in organisms
  • DNA carries inheritable characteristics

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Related Documents

Molecular Biology Practical No.2 DNA as a carrier PDF

Description

Explore the groundbreaking experiments of Frederick Griffith that revealed DNA as the carrier of genetic information. This quiz delves into the transformation phenomenon observed in Streptococcus pneumoniae bacteria and its implications for understanding genetic inheritance. Test your knowledge on bacterial transformation and the early foundations of molecular biology.

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