7 Questions
What is the shape of the bacterial chromosome?
Circular
What is the replication mode of DNA in bacteria?
Semi-conservative
What is the characteristic of plasmids?
Self-replicating extra chromosomal DNA molecules
What do R factors code for?
Antibiotic resistance
What is the function of F factors?
Promote transfer of the chromosome at a high frequency of recombination
What is a characteristic of plasmid distribution in bacterial cells?
Multiple copies of the same plasmid may be present in each bacterial cell
What do Col factors code for?
Extracellular toxin production
Study Notes
Bacterial Chromosome
- The bacterial chromosome is a circular, double-stranded DNA molecule attached to the bacterial cell membrane.
DNA Replication in Bacteria
- DNA replication in bacteria is semi-conservative, meaning each original DNA strand is conserved intact during replication and becomes one of the two strands of the new daughter molecules.
Plasmids
- Plasmids are self-replicating, extra-chromosomal DNA molecules that multiply independently of the host cell.
- Multiple copies of the same plasmid can be present in each bacterial cell.
- Different plasmids can also be present in the same bacterial cell.
Types of Plasmids
- R factors: Plasmids that contain genes coding for antibiotic resistance.
- Col factors: Plasmids that contain genes coding for extracellular toxin (colicines) production, which inhibit strains of the same and different species of bacteria.
- F (fertility) factors: Plasmids that can recombine with the bacterial chromosome, promoting the transfer of the chromosome at a high frequency of recombination into the chromosome of a second (recipient) bacterial cell during mating.
This quiz covers the structure and replication of bacterial chromosomes and plasmids. Learn about the characteristics of circular DNA, semi-conservative replication, and the independence of plasmids from the host cell.
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