15 public questions tagged with this topic.
Antibiotic resistance genes act as selectable markers, helping identify bacterial lls that have taken up the recombinant plasmid. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.
Ref: NCERT Biology Textbook for Class XI and XII (Zoology section), Chapter: Biology - Zoology portion covering relevant system and function.
Vertical inheritance through binary fission faithfully copies the single circular chromosomal DNA with high fidelity via DNA polymerase III holoenzyme but fails to explain extraordinarily rapid global dissemination of antibiotic resistance observed within decades of antibiotic introduction. Horizontal gene transfer provides direct mechanism for movement of accessory genes between genetically unrelated cells, even across genus barriers. Conjugation involves direct cell-to-cell contact via retractile sex pilus encoded by tra operon and transfer of conjugative plasmids and integrative conjugative
Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 5: Horizontal Gene Transfer and Resistance Spread.
Biofilms represent structured multicellular communities where bacteria irreversibly attach to biotic or abiotic surfaces and embed themselves in self-produced extracellular polymeric substances composed of exopolysaccharides such as alginate and Psl, extracellular DNA released via lysis, proteins, amyloids and lipids anchored via adhesins like CsgA curlin and Bap. Within biofilm microenvironments, steep gradients of oxygen, nutrients and pH create heterogeneous populations including dormant persister cells with low metabolic activity and downregulated macromolecular synthesis that are phenotyp
Ref: Madigan et al., Brock Biology of Microorganisms, 16th ed., Chapter 19: Biofilms and Increased Antibiotic Resistance.
Efflux-mediated resistance represents highly efficient active extrusion mechanism driven by transmembrane energy gradients. Bacterial multidrug efflux systems belong to five major families: resistance-nodulation-division RND such as AcrAB-TolC tripartite pump in Escherichia coli and MexAB-OprM in Pseudomonas aeruginosa, major facilitator superfamily MFS such as TetA for tetracycline, multidrug and toxic compound extrusion MATE, small multidrug resistance SMR and ATP-binding cassette ABC transporters using ATP hydrolysis rather than proton motive force. These pumps capture antibiotics from peri
Ref: Lodish et al., Molecular Cell Biology, 8th ed., Chapter 15: Bacterial Efflux Pumps and Drug Resistance.
Resistance to beta-lactam antibiotics including penicillins, cephalosporins, monobactams and carbapenems frequently arises through enzymatic destruction rather than target alteration. Beta-lactamases are hydrolases classified into Ambler molecular classes A to D based on amino acid sequence homology and catalytic mechanism. Serine beta-lactamases, including plasmid-encoded TEM-1, SHV-1, extended-spectrum beta-lactamases CTX-M and serine carbapenemases KPC, employ an active-site serine residue that performs nucleophilic attack on carbonyl carbon of the strained beta-lactam ring, forming a trans
Ref: Prescott's Microbiology, 11th ed., Chapter 36: Beta-Lactamase Enzymes and Antibiotic Resistance.
Plasmid-mediated antibiotic resistance illustrates extraordinary plasticity of bacterial accessory genome and its clinical impact. Resistance R-plasmids and conjugative plasmids frequently carry multiple gene cassettes encoding distinct resistance mechanisms: beta-lactamases including TEM, SHV, CTX-M that hydrolyze beta-lactam rings, aminoglycoside-modifying enzymes such as acetyltransferases AAC, phosphotransferases APH, nucleotidyltransferases ANT that acetylate, phosphorylate or adenylate aminoglycosides, macrolide efflux pumps encoded by mef genes and target modification via erm methylases
Ref: Madigan et al., Brock Biology of Microorganisms, 16th ed., Chapter 9: Plasmid-Mediated Multidrug Resistance Mechanisms.
Selectable markers, such as antibiotic resistance genes, help identify transformed cells by allowing only recombinant cells to survive.
Ref: NCERT Class 12 Biology Chapter 9: Biotechnology: Principles and Processes Bioreactors and Downstream Processing
Selectable markers, such as antibiotic resistance genes, allow researchers to identify and isolate transformed cells.
Ref: NCERT Class 12 Biology Chapter 9: Biotechnology: Principles and Processes Bioreactors and Downstream Processing
Selectable markers, such as antibiotic resistance genes, help in identifying recombinant cells.
Ref: NCERT Class 12 Biology Chapter 9: Biotechnology: Principles and Processes Cloning Vectors - Plasmids Phages Cosmids Selectable Markers Ori
Selectable markers do not inhibit bacterial growth but rather help distinguish transformed from non-transformed cells.
Ref: NCERT Class 12 Biology Chapter 9: Biotechnology: Principles and Processes Cloning Vectors - Plasmids Phages Cosmids Selectable Markers Ori
Selectable markers, such as antibiotic resistance genes, help distinguish transformed cells from non-transformed cells.
Ref: NCERT Class 12 Biology Chapter 9: Biotechnology: Principles and Processes Principles of Biotechnology - Genetic Engineering
Mycoplasmas are among the smallest cells, approximately 0.3 µm long, and lack a cell wall. Plasmids are small circular DNA molecules outside the bacterial genomic DNA. They can confer properties such as antibiotic resistance and help monitor transformation with foreign DNA.
Ref: NCERT Class 11 Biology Chapter 8: Cell: The Unit of Life Prokaryotic Cell - Structure and Components
