Ampicillin Resistance
Ampicillin Resistance - Related Videos
12:52
Conjugation: A Method to Transfer Ampicillin Resistance from Donor to Recipient E. coli
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2023
Source: Alexander S. Gold1, Tonya M. Colpitts1 1 Department of Microbiology, Boston University School of Medicine, National Emerging Infections Diseases Laboratories, Boston, MA First discovered by Lederberg and Tatum in 1946, conjugation is a form of horizontal gene transfer between bacteria that relies on direct physical contact between two bacterial cells (1). Unlike other forms of gene transfer, such as transformation or transduction, conjugation is a naturally occurring process in which...
11:21
Phage Transduction: A Method to Transfer Ampicillin Resistance from Donor to Recipient E. coli
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2023
Source: Alexander S. Gold1, Tonya M. Colpitts1 1 Department of Microbiology, Boston University School of Medicine, National Emerging Infections Diseases Laboratories, Boston, MA Transduction is a form of genetic exchange between bacteria that utilizes bacteriophages, or phages, a class of virus that infects exclusively prokaryotic organisms. This form of DNA transfer, from one bacterium to another by way of a phage, was discovered in 1951 by Norton Zinder and Joshua Ledererg, who termed the...
03:14
Assessing the Role of Gene Copy Number in the Evolution of Bacterial Antibiotic Resistance
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2026
Source: Escudero, J. A., et.al. Testing the Role of Multicopy Plasmids in the Evolution of Antibiotic Resistance. J. Vis. Exp. (2018)This video demonstrates how escalating cefazidime exposure is used to compare the survival of three E. coli strains with different copies of the ampicillin resistance gene. It shows that only the strain with a multicopy plasmid survives at higher drug levels, highlighting how increased gene copy number accelerates resistance evolution.
08:10
Measuring Oxidative Stress Resistance of Caenorhabditis elegans in 96-well Microtiter Plates
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Cited by 43 •
2015
C. elegans is an attractive model organism to study signal transduction pathways involved in oxidative stress resistance. Here we provide a protocol to measure oxidative stress resistance of C. elegans animals in liquid phase, using several oxidizing agents in 96 well plates.
01:22
Resistivity
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2023
When a voltage is applied to a conductor, an electrical field is generated, and charges in the conductor feel the force due to the electrical field. The current density that results depends on the electrical field and the properties of the material. In some materials, including metals at a given temperature, the current density is approximately proportional to the electrical field. In these cases, the current density can be modeled as: where σ is the electrical conductivity and is represented...
FAQs
β-lactamase provides a direct chemical defense by hydrolyzing ampicillin’s β-lactam ring before the antibiotic can exert its normal effect. This mechanism differs from altered penicillin-binding proteins, which changes the drug’s target, and from reduced entry or increased efflux, which limits the drug’s access. Comparing these mechanisms helps distinguish enzymatic inactivation from target or transport-based resistance.
Target-based resistance and transport-based resistance interfere with different stages of antibiotic action. Altered penicillin-binding proteins reduce the effectiveness of ampicillin at its cellular target, whereas reduced entry or increased efflux lowers the amount reaching that target. This distinction matters because resistance can arise through changes in target interaction, intracellular access, or enzymatic drug destruction.
In cloning experiments, an ampicillin-resistance marker acts as a practical identifier for bacteria that carry a genetically modified plasmid. After transformation, researchers can use ampicillin exposure to favor cells containing that marker, then maintain those cells during plasmid propagation. The marker therefore links survival under selection with retention of the engineered genetic material during bacterial growth.
At a conceptual level, selection uses ampicillin exposure to separate bacteria carrying the resistance marker from bacteria that lack it. Researchers then maintain the selected bacteria under conditions that preserve the marker while propagating the plasmid. The outcome is a population enriched for genetically modified cells, making resistance a selection tool rather than the genetic modification itself.
Studying ampicillin resistance connects a laboratory selection trait to larger biological processes. Resistance genes can illustrate how bacteria evolve under antibiotic exposure and how genetic traits may move between bacteria through horizontal gene transfer. In this context, a resistance marker is not only a cloning convenience; it also provides a model for examining how resistance traits arise, persist, and spread.
Clinical relevance comes from the fact that the same resistance mechanisms that complicate laboratory selection can reduce the effectiveness of antibiotic treatment. Examining β-lactamase activity, altered penicillin-binding proteins, reduced drug entry, and increased efflux places ampicillin resistance within antimicrobial resistance more broadly. This perspective connects bacterial survival mechanisms with their consequences for treatment.