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What is the primary mechanism of genetic exchange in sexual reproduction in microbes?
What is the result of recombination in prokaryotes?
What is the significance of sexual reproduction in microbes?
What is an example of a phenomenon involving genomic rearrangements?
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What is the definition of a core genome?
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What is an example of horizontal gene transfer?
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What is the result of horizontal gene transfer?
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What is the difference between core genome and accessory genome?
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What is the purpose of genetic exchange in microbes?
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What is the mechanism of genetic exchange in transformation?
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What is the primary function of F plasmid conjugative functions?
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What is the role of F pili in bacterial conjugation?
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What is the outcome when an F- strain of bacteria receives an F plasmid?
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What is the term for bacterial strains that have an integrated F plasmid in their chromosome?
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Why is conjugation useful for mapping the location of genes in a bacterial chromosome?
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What is the consequence of not circularizing the transferred DNA in the recipient cell?
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What is the purpose of interrupted-mating experiments in bacterial conjugation?
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What is the difference between F+ and F- strains of bacteria?
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What is the purpose of the outer membrane protein (ompA gene product) in bacterial conjugation?
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What is the result of recombination between the transferred DNA and the recipient chromosome?
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What is the primary factor that influences a bacteria's ability to take up DNA and undergo transformation?
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Which of the following laboratory manipulations is used to induce competence in bacteria?
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What is the primary outcome of Griffith's experiment?
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What is the term for the process by which bacteriophages introduce donor DNA into recipient bacteria?
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What is the primary difference between generalized transduction and specialized transduction?
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What is the term for the transient expression of one or more donor genes without the formation of recombinant progeny?
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What is the primary mechanism of conjugation?
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What is the term for the bacteriophage that contains part of the bacterial genome adjacent to the prophage attachment site?
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What is the primary role of fertility plasmids or sex plasmids in conjugation?
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What is the outcome of complete transduction?
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What is the percentage of recipients that were scored as his+ in the interrupted mating experiment?
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What type of recombination involves the breaking and joining of parental DNA molecules to form recombinant molecules?
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What is the term for the moving of DNA segments from one site to another?
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What is the name of the enzyme responsible for transposition?
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What type of recombination is involved in the formation of recombinant molecules?
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What is the result of illegitimate recombination?
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What is the purpose of interrupted mating in the experiment?
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What is the result of transposition?
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What is the type of recombination involved in transposition?
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What is the term for the movement of DNA segments from one site to another without the involvement of generalized recombination?
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Study Notes
Genetic Exchange in Prokaryotes
- Genetic exchange/recombination of genetic material in prokaryotes leads to offspring with genetic diversity, maximizing the probability of variation.
Sexual Reproduction
- Prokaryotes have simpler mechanisms for genetic exchange, such as cell-cell transfer and genetic uptake.
- Some microbes can produce gametes, and entire microbial cells can act as gametes in some cases.
- Most prokaryotes do not have a distinct fertilization event.
Sexual Reproduction in Prokaryotes
- Transfer of donor DNA to a recipient, resulting in offspring genetically different from the parental organism.
- Recombination requires stable hybrid progeny, with a higher probability of occurrence between closely related species.
Significance of Sexual Reproduction
- Higher probability of mutations and natural selection in a microbe population, leading to faster evolution.
- Examples of phenomena involving genomic rearrangements include AR plasmids, flagellar phase variation, and antigenic variation.
Horizontal Gene Transfer
- Lateral gene transfer, also known as non-vertical gene transfer, occurs between microorganisms.
- Core genome: set of genes encoding fundamental metabolic functions present in all taxon members.
- Accessory genome: set of non-essential genes encoding traits associated with drug resistance, virulence, and degradation of xenobiotic compounds.
Transformation
- Uptake of free DNA fragments from the environment by competent bacteria.
- Competence: the ability of a bacterium to take up DNA and be transformed, varying with physiological state.
Griffith's Experiment
- In 1928, Frederick Griffith demonstrated the conversion of non-pathogenic pneumococcal bacteria to a virulent strain using Streptococcus pneumoniae and mice.
Transduction
- Bacteriophages function as vectors to introduce donor DNA into recipient cells.
- Abortive transduction: transient expression of one or more donor genes without formation of recombinant progeny.
- Complete transduction: characterized by production of stable recombinant genes that inherit donor genes and retain the ability to express them.
Generalized Transduction
- Aberrant virulent phages contain bacterial genome instead of phage DNA.
Specialized Transduction
- Mediated by temperate phages, transferring few specific donor genes to recipient cells.
- Transducing phage contains part of the bacterial genome adjacent to the prophage attachment site.
Conjugation
- Direct transfer of genetic material between bacteria through cell-to-cell contact.
- Donor ability is determined by specific fertility plasmids or sex plasmids.
F Plasmid
- A prototype for fertility plasmids in Gram-negative bacteria.
- F+ donors and F- recipients, with conjugative functions specified by >25 TRA genes.
Mapping Genes
- Conjugation can be used to map the location of genes in a bacterial chromosome.
- Greater distance from the F origin = lower probability of donor gene getting into the recipient.
Recombination
- Involved in the breaking and joining of parental DNA molecules to form recombinant molecules.
- Enzymes involved: exonucleases, endonucleases, polymerases, and ligases.
- Nonhomologous aberrant recombination = illegitimate recombination.
Transposons
- DNA segments that can move from one site to other target sites through transposition.
- Cause mutations, mediate genomic rearrangements, and acquire new genes.
Transposition Types
- Non-replicative transposition: "cut and paste."
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Description
This quiz covers genetic exchange and sexual reproduction in prokaryotes, including mechanisms for genetic diversity and variation in microbes.
