26 Questions
What is the time required for microbial cells to double in number?
Generation time
What protein binds to the origin of replication (oriC) and initiates bidirectional DNA synthesis in bacteria?
DnaA
What prevents additional rounds of replication by blocking DnaA from binding to the oriC region?
SeqA binding to hemimethylated DNA
What do fast-growing cells with generation times less than the replication time contain?
Multiple replication forks
What is the major shape-determining factor in bacteria?
MreB
What is the function of the Par system and PopZ in bacteria?
Distribute chromosomes and plasmids equally
What is the role of Min proteins in bacterial cell division?
Ensure the divisome forms at the center of the cell
What is a major feature of cell division in bacteria?
Peptidoglycan biosynthesis
What is the function of bactoprenol in bacterial cell division?
Carries peptidoglycan precursors through the cytoplasmic membrane
What triggers biofilm formation in Vibrio cholerae?
Low cell densities
What is the role of cyclic di-GMP signaling in biofilm formation?
Triggers biofilm formation
What is the function of Fts proteins in bacterial cell division?
Essential for binary fission
What is the function of PopZ in bacterial cell division?
Recruit proteins involved in cell wall growth
What is the function of the divisome in bacterial cell division?
Synthesize new cytoplasmic membrane and cell wall material
What is the role of SEDS proteins in bacterial cell division?
Recruit proteins involved in cell wall growth
What is the function of Pseudomonas aeruginosa polysaccharides in biofilm formation?
Increase pathogenicity and prevent antibiotic penetration
What is the mechanism of action of Daptomycin?
Binding to phosphatidylglycerol residues of the bacterial cytoplasmic membrane, leading to pore formation, depolarization, and death
Which antibiotic binds to pentapeptide precursor and prevents interbridge formation?
Vancomycin
What are the genetically encoded classes of antibiotic resistance mechanisms?
Modification of drug target, enzymatic inactivation, removal via efflux pumps, metabolic bypasses
What is the function of efflux pumps in antibiotic resistance?
Transporting various molecules, including antibiotics, out of the cell
What makes the antibiotic target no longer essential in antibiotic resistance?
A metabolic bypass
What is the role of persisters in antibiotic resistance?
Transiently tolerant to multiple antibiotics
What do toxin-antitoxin (TA) modules encode?
A toxin which inhibits cell growth and an antitoxin that binds and counteracts the toxin
What does HipA do in the stringent response pathway?
Phosphorylates glutamyl-tRNA synthetase, preventing the tRNA synthetase from charging amino acids
What induces the stringent response pathway?
Uncharged tRNA entering the A site of the ribosome
What allows persisters to exit the stringent response pathway?
Production of HipB (or other antitoxin)
Study Notes
Bacterial Cell Division, Morphology, Biofilm Formation, and Antibiotic Targets
- Chromosome segregation is necessary for distributing chromosomes and plasmids equally to daughter cells and for septum formation
- Bacteria use the Par system and PopZ to distribute chromosomes and plasmids equally
- The divisome, made up of Fts proteins, is essential for binary fission and involves the synthesis of new cytoplasmic membrane and cell wall material
- Min proteins ensure the divisome forms at the center of the cell and prevent the FtsZ ring from forming elsewhere
- Bacteria contain shape-determining proteins such as MreB and SEDS proteins
- MreB is the major shape-determining factor in bacteria and recruits other proteins involved in cell wall growth
- Bacterial cell morphologies vary, and morphology is typically unrelated to phylogeny
- Peptidoglycan biosynthesis is a major feature of cell division, and bactoprenol carries peptidoglycan precursors through the cytoplasmic membrane
- Biofilm formation involves initial attachment, cyclic di-GMP signaling, and gene expression for intercellular communication and extracellular polysaccharides
- Pseudomonas aeruginosa forms a tenacious biofilm with polysaccharides that increase pathogenicity and prevent antibiotic penetration
- Vibrio cholerae biofilm formation is triggered by low cell densities and repressed by high densities, and is more likely to occur in natural marine environments
- Antibiotics target essential molecular processes such as DNA replication, RNA synthesis, translation, and protein synthesis, and some target specific bacterial structures and enzymes, like DNA gyrase, topoisomerase IV, and RNA polymerase
Test your knowledge of bacterial cell division, morphology, biofilm formation, and antibiotic targets with this quiz. From chromosome segregation to biofilm formation and antibiotic resistance mechanisms, this quiz covers essential concepts in bacterial biology.
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