16 Questions
What was the primary conclusion Griffith made from his experiment with S-type and R-type bacteria?
Genetic information can be transferred between bacteria.
Why did mice survive when injected with heat-killed S-type bacteria alone?
Heat-killed bacteria do not retain disease-causing capabilities.
What did Griffith deduce as the factor responsible for transformation?
A gene
What was the unexpected result Griffith observed when he injected mice with a mixture of heat-killed S-type bacteria and live R-type bacteria?
The mice developed pneumonia and died.
What did Griffith find in the lungs of mice that died after being injected with the mixture of heat-killed S-type and live R-type bacteria?
Live disease-causing bacteria
Why did Griffith call the process he discovered 'transformation'?
Because one bacterial form was changed permanently to another
What was Frederick Griffith investigating in 1928?
How bacteria produce pneumonia
What significance did Griffith attribute to the 'chemical compound' involved in transformation?
It contained information responsible for causing disease.
What did Griffith's experiment ultimately suggest about the nature of genetic material?
It is capable of being transferred between organisms.
Which type of bacteria caused pneumonia in Griffith's experiments?
The S type
What characteristic distinguished the S type bacteria from the R type in Griffith's experiments?
S type bacteria had smooth-edged colonies
What conclusion can be drawn from Griffith's experiments regarding the mice injected with harmless bacteria?
The mice remained healthy
What key question did biologists have about genetics a hundred years ago?
What is the chemical nature of genes?
In the context of heredity, what have scientists inferred about the role of DNA?
DNA is the molecule that carries genetic information
Why were the appearances of bacterial colonies critical in Griffith's research?
To differentiate between disease-causing and harmless types
According to the provided content, what was not a goal of Griffith’s experiments?
Investigate the molecular structure of genes
Study Notes
Identifying the Substance of the Gene
- Genes are made up of a chemical substance that carries genetic information, which determines the physical traits of an organism.
- Frederick Griffith's experiment in 1928 aimed to discover the chemical nature of the gene.
Bacterial Transformation
- Griffith isolated two types of bacteria: S-type (disease-causing) and R-type (harmless), distinguishable by their colony shapes on culture plates.
- Griffith's experiment involved injecting mice with various bacterial combinations to understand the cause of pneumonia.
- Heat-killed S-type bacteria did not cause pneumonia in mice, suggesting it was not a poison.
- Mixing heat-killed S-type bacteria with live R-type bacteria led to pneumonia in mice, indicating a chemical factor was transferred.
Transformation
- Griffith coined the term "transformation" to describe the process by which the chemical factor changed harmless bacteria into disease-causing ones.
- This experiment showed that genetic information can be transferred from one bacterial type to another.
- The transforming factor was concluded to be a gene, as the ability to cause disease was inherited by the offspring of the transformed bacteria.
Discover the clues from bacterial transformation and bacteriophages that led to the discovery of DNA as the genetic material. Learn about the experiments that helped scientists understand genes and DNA.
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