Questions and Answers
What is transformation in bacteria?
What does conjugation involve in bacteria?
What does the term 'donor' refer to in bacterial conjugation?
A plasmid called F factor, transferred to recipient
What are Hfr strains known for?
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What is transduction in bacteria?
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Define auxotrophs.
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What does 'Replica plating' refer to?
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What does competent cells mean?
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Two genes must be close together if the frequency of cotransformation is higher than expected.
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Who discovered the F factor?
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Define transconjugants.
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Study Notes
Transformation
- Involves uptake and incorporation of extracellular DNA by bacterial cells, leading to genetic modification.
Conjugation
- Direct DNA transfer between two bacteria through temporary cell connection.
- Requires a donor cell with an F factor plasmid, which gets transferred to the recipient.
Hfr Strains
- High frequency recombination results from integration of the F factor into a bacterial chromosome.
Transduction
- Genetic material transfer between bacteria mediated by a plasmid or bacteriophage.
Mapping Techniques
- Intergenic Mapping: Measures distance between mutations in different genes.
- Intragenic Mapping: Measures distance between mutations within the same gene.
Cis-Trans Test
- Determines whether mutations in viral genes complement each other based on their gene location; mutations in different genes complement, while mutations in the same gene do not.
Auxotrophs vs. Prototrophs
- Auxotrophs: Mutants unable to synthesize essential nutrients, requiring them from media.
- Prototrophs: Capable of synthesizing all necessary nutritional requirements.
Mutation Notation
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- superscript indicates wild type capable of synthesis; absence indicates mutant unable to synthesize.
Replica Plating
- Technique for isolating auxotrophs by transferring bacterial colonies onto selective media, allowing differentiation between prototrophs and auxotrophs.
Transformants
- Recombinant bacterial cells that exhibit altered phenotypes after transformation.
Electroporation
- Method introducing DNA into cells by applying an electrical pulse, creating pores in cell membranes for DNA entry.
Competent Cells
- Bacteria that can naturally uptake and integrate external DNA.
Transformation Types
- Natural Transformation: Uptake of free DNA naturally occurring in species like Bacillus subtilis.
- Engineered Transformation: Bacteria, such as E. coli, are modified to enhance DNA uptake capabilities.
Heteroduplex DNA
- Hybrid DNA formed from complementary strands of similar, but not identical, DNA molecules.
Gene Linkage
- Two genes are considered closely related if cotransformation frequencies are higher than expected based on individual transformation rates, indicating they are often inherited together.
Transconjugants
- Bacteria that successfully receive DNA from a donor during conjugation.
Key Discoveries
- Conjugation was established by Lederberg and Tatum.
- F factor discovery credited to William Hayes.
F pili/Sex pili
- Specialized structures that facilitate DNA transfer between bacteria, encoded by the F plasmid.
Conjugation Limitations
- No conjugation occurs between cells of the same mating type (F+ with F+ or F- with F-).
Effects of Continued Conjugation
- Results in increased proportion of F+ cells in the bacterial population over time.
Curing
- Chemical exposure that hinders the replication of the F factor.
Genetic Transfer in F+ F- Crosses
- Transfers only the F factor and not the bacterial chromosome during F+ and F- cell interactions.
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Description
Explore important concepts in bacterial genetics with this quiz. Focus on transformation, transduction, and conjugation processes, learning through various flashcards. Perfect for students wanting to solidify their understanding of microbiology.
