All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources
Example Question #1 : Help With Transduction, Conjugation, And Transformation
The Frederick Griffith experiment showed that previously safe pneumococcus can become lethal when it incorporates DNA from the surroundings into its genome.
What type of genetic transfer was displayed in the Frederick Griffiith experiment?
When a bacterium has incorporated DNA from the outside environment into its own genome, the process of transformation has occurred.
Example Question #2 : Help With Transduction, Conjugation, And Transformation
Which type of bacterial genetic recombination involves the use of a viral vector?
Sometimes a bacteriophage can encapsulate host bacterial DNA instead of viral DNA. When this virus infects another bacterium, it will inject the previous bacterium's DNA into the new bacterium. This process is referred to as transduction.
Example Question #3 : Help With Transduction, Conjugation, And Transformation
What plasmid, usually in multiple copies in a prokaryote, is responsible for production of proteins to attack susceptible organisms?
The correct answer is the Col plasmid, which produce attack proteins called colicins. These are generally small and in many copies in a prokaryote for efficiency. F plasmids are involved in conjugation, R plasmids in resistance, degradative plasmids in digestion of unusual substances, and virulence plasmids in the conversion of certain bacteria into pathogens.
Example Question #4 : Help With Transduction, Conjugation, And Transformation
What type of phages facilitate specialized transduction?
None of these
Specialized transduction occurs when a prophages excises from the host bacterial genome incorrectly and brings some of the bacterial chromosome with it. This DNA then gets packaged into viral particles along with the viral genome and gets inserted into the next bacterium that virus infects. Since only lysogenic phage can become prophage, specialized transduction can only be mediated by lysogenic phage. Retroviruses are enveloped and thus infect animal cells, not bacterial cells.
Example Question #5 : Help With Transduction, Conjugation, And Transformation
Bacteria are capable of "sharing" genetic material that can be advantageous in certain environments. This type of gene transmission is an example of which of the following?
In this example, note that the new genes are being received from a donor bacterium. This is only seen in conjugation events.