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What is the primary method of transfer of antibiotic resistance genes from one bacterium to another?
What is the primary method of transfer of antibiotic resistance genes from one bacterium to another?
What is the role of the F plasmid in bacterial conjugation?
What is the role of the F plasmid in bacterial conjugation?
Which of the following proteins is involved in the formation of the sex pilus during conjugation?
Which of the following proteins is involved in the formation of the sex pilus during conjugation?
What is the term for the bacterial cells that have their F plasmid integrated into the bacterial DNA?
What is the term for the bacterial cells that have their F plasmid integrated into the bacterial DNA?
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What is the result of the integration of the donor cell genes into the recipient's DNA during conjugation?
What is the result of the integration of the donor cell genes into the recipient's DNA during conjugation?
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What is the primary method of transfer of exotoxin genes from one bacterium to another?
What is the primary method of transfer of exotoxin genes from one bacterium to another?
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What is the composition of the single strand of DNA that enters the recipient F– cell during conjugation?
What is the composition of the single strand of DNA that enters the recipient F– cell during conjugation?
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What type of mutation occurs when one or more base pairs are added or deleted?
What type of mutation occurs when one or more base pairs are added or deleted?
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What is the primary difference between vertical and horizontal gene transfer?
What is the primary difference between vertical and horizontal gene transfer?
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What is the primary function of an R (resistance) factor plasmid?
What is the primary function of an R (resistance) factor plasmid?
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What is the main characteristic of transposons?
What is the main characteristic of transposons?
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What is the primary function of an Hfr plasmid in conjugation?
What is the primary function of an Hfr plasmid in conjugation?
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What is the main difference between generalized and specialized transduction?
What is the main difference between generalized and specialized transduction?
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What is the result of a nonsense mutation?
What is the result of a nonsense mutation?
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What is the term for the process by which a bacteriophage integrates its DNA into the host genome, resulting in the acquisition of a new trait?
What is the term for the process by which a bacteriophage integrates its DNA into the host genome, resulting in the acquisition of a new trait?
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What is the term for the integrated form of a plasmid with DNA?
What is the term for the integrated form of a plasmid with DNA?
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What is the primary function of an F (fertility) factor plasmid?
What is the primary function of an F (fertility) factor plasmid?
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What is the primary requirement for a recipient cell to undergo transformation?
What is the primary requirement for a recipient cell to undergo transformation?
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Which of the following is NOT a result of transformation?
Which of the following is NOT a result of transformation?
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What is the primary vector for gene transfer in transduction?
What is the primary vector for gene transfer in transduction?
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What is the term for the process of gene transfer from one bacterium to another through direct cell-to-cell contact?
What is the term for the process of gene transfer from one bacterium to another through direct cell-to-cell contact?
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What is the main difference between haploid and diploid cells?
What is the main difference between haploid and diploid cells?
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What is the function of the electron transport chain in anaerobic respiration?
What is the function of the electron transport chain in anaerobic respiration?
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What is the product of fermentation in the production of alcoholic beverages?
What is the product of fermentation in the production of alcoholic beverages?
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What is the term for the complete set of genetic information in a cell?
What is the term for the complete set of genetic information in a cell?
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What is the purpose of amination or transamination in biosynthesis?
What is the purpose of amination or transamination in biosynthesis?
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What is the shape of the genetic material of a typical bacterium?
What is the shape of the genetic material of a typical bacterium?
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What is the term for a segment of DNA that codes for a functional product?
What is the term for a segment of DNA that codes for a functional product?
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What is the byproduct of anaerobic respiration in muscles?
What is the byproduct of anaerobic respiration in muscles?
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What is the term for the expression of genes in an organism?
What is the term for the expression of genes in an organism?
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Study Notes
DNA Transfer between Bacterial Cells
- DNA transfer occurs through three methods: conjugation, transduction, and transformation.
- Conjugation: the mating of two bacterial cells, where DNA is transferred from the donor to the recipient cell, controlled by an F (fertility) plasmid.
Conjugation
- F plasmid carries genes for proteins required for conjugation, including pilin, which forms the sex pilus (conjugation tube).
- High-frequency recombination (Hfr) cells: F+ cells with integrated F plasmid into bacterial DNA, allowing for higher frequency of recombination.
- Hfr plasmid conjugation: increases probability of recombination by incorporating directly into the host genome.
Transduction
- Virus (bacteriophage) acts as a genetic vector, passing DNA from donor to recipient.
- Donor DNA incorporates into recipient DNA, and the bacteriophage containing the bacterial DNA is called transduced DNA.
- Two types of transduction: generalized transduction (random) and specialized transduction (specific genes).
- Transduction can occur in various prokaryotes, including Escherichia coli, Pseudomonas, Salmonella, and Staphylococcus.
Lysogenic Conversion
- The phage DNA can integrate into the cell DNA, and the cell can acquire a new trait, changing a nonpathogenic organism into a pathogenic one.
- Examples of toxins encoded by bacteriophages and transferred by transduction: diphtheria toxin, botulinum toxin, cholera toxin, and erythrogenic toxin.
Transformation
- The transfer of DNA itself from one cell to another, where naked DNA is transferred from a dead donor into a competent recipient.
- Competent recipient: young, actively dividing, or has receptors; donor and recipient are usually closely related.
- Donor DNA recombines with recipient, conferring traits such as virulence factors and antibiotic resistance.
Mutations
- Base substitution: when one base is replaced by another, resulting in a different amino acid being inserted.
- Missense mutation: when the base substitution results in a codon that causes a different amino acid to be inserted.
- Nonsense mutation: when the base substitution generates a termination codon that stops protein synthesis prematurely.
- Frameshift mutation: when one or more base pairs are added or deleted, shifting the reading frame and resulting in the incorporation of wrong amino acids.
Gene Transfer
- Genetic recombination: the process of combining genetic information from two different sources.
- Vertical gene transfer: occurs during reproduction between generations of cells.
- Horizontal gene transfer: the transfer of genes between cells of the same generation.
Plasmids
- Can be integrated with chromosomal DNA, forming episomes.
- Types of plasmids: F (fertility) factor, R (resistance) factor, bacteriocin factor, and virulence factor.
Transposons
- Small DNA segments that can move within the same chromosome or to different chromosomes or plasmids.
- Copy their DNA and insert the copy at another site in the bacterial chromosome or plasmid.
Bacterial Genetics
- Gene: a segment of DNA coding for a functional product.
- Chromosome: a structure made of DNA that contains the genes, carrying hereditary information.
- Genome: all the genetic information in a cell.
- Genotype: the genes of an organism.
- Phenotype: the expression of the genes.
Bacterial Chromosomes
- Bacteria are haploid, with a single chromosome and a single copy of each gene.
- Eukaryotic cells are diploid, with a pair of each chromosome and two copies of each gene.
- The genetic material of a typical bacterium, such as Escherichia coli, consists of a single circular DNA molecule with a molecular weight of about 2 x 10^9 and approximately 5 x 10^6 base pairs.
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Description
Learn about the three methods of genetic information transfer between bacterial cells: conjugation, transduction, and transformation. Understand the medical implications of DNA transfer, including the spread of antibiotic resistance genes and exotoxins.
