DNA-Mediated Transformation Flashcards
What are the three methods by which bacteria can acquire genetic material?
Conjugation, transduction, transformation
Conjugation involves direct cell-to-cell contact, transduction involves a bacteriophage introducing DNA, and transformation involves the uptake of naked DNA from the environment.
What term describes a bacterium’s ability to take up DNA from the environment?
Genetic competence
Genetic competence varies among different bacterial species.
Which bacterium is always naturally competent?
Acinetobacter
Acinetobacter is a Gram-negative, non-motile rod found in soil and water.
When is Bacillus competent for transformation?
During the transition from exponential growth to stationary phase
Competence in Bacillus is not continuous like in Acinetobacter.
How can E. coli be made competent in the laboratory?
By suspending cells in dilute solutions of calcium chloride
This method enhances the uptake of DNA by E. coli.
What is a genetic marker?
A gene encoding an observable trait that’s absent in the recipient cell
Genetic markers are crucial for determining the success of transformation.
What observable trait is used as a genetic marker in the experiment?
The ability to synthesize the amino acid tryptophan
This allows for selection of transformed cells on minimal media.
What are prototrophs?
Organisms that can grow on minimal media with a single carbon source
They can synthesize all necessary organic metabolites for growth.
What are auxotrophs?
Organisms that lack the ability to synthesize one or more essential metabolites
Auxotrophs require specific nutrients to grow, unlike prototrophs.
What will happen to tryptophan auxotrophs if they acquire the tryptophan genes?
They will become prototrophs and grow on minimal medium without tryptophan
This demonstrates the successful transformation of the recipient cells.
What is the importance of controls in scientific research?
Controls ensure the reliability and validity of experimental results
Proper experimental design is critical for drawing accurate conclusions.
What is the purpose of SDS in the experiment?
To lyse the cells, releasing DNA and other cellular contents
SDS is a detergent that breaks down cell membranes.
What is the expected outcome of the tube after incubation with SDS?
The solution should become very slimy and viscous due to released DNA
High temperature kills unlysed cells, leaving only naked DNA.
Fill in the blank: The minimal medium used in the experiment is called _______.
Acinetobacter broth
This medium supports the growth of prototrophic Acinetobacter.
True or False: Auxotrophic Acinetobacter can grow on minimal media without tryptophan.
False
Auxotrophs require tryptophan supplied in the media to grow.
