Plasmid Loss
Plasmid Loss - Related Videos
08:16
Plasmid Purification
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2023
Plasmid purification is a technique used to isolate and purify plasmid DNA from genomic DNA, proteins, ribosomes, and the bacterial cell wall. A plasmid is a small, circular, double-stranded DNA that is used as a carrier of specific DNA molecules. When introduced into a host organism via transformation, a plasmid will be replicated, creating numerous copies of the DNA fragment under study. In this video, a step-by-step generalized procedure is described for how to perform plasmid purification.
01:10
Line Loss
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2024
The different configurations of source-load connections include wye (star) and delta connections. The relationship between line and phase voltages and currents varies depending on the configuration. When the source is supplying power, it is transmitted through the wires to the load, and during this transmission, some power is absorbed by the wires, leading to line loss. Line loss impacts power delivery efficiency in a balanced three-phase circuit. The symmetry in such a circuit simplifies the...
12:27
Piping Networks and Pressure Losses
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2023
Source: Alexander S Rattner, Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA This experiment introduces the measurement and modeling of pressure losses in piping networks and internal flow systems. In such systems, frictional flow resistance from channel walls, fittings, and obstructions causes mechanical energy in the form of fluid pressure to be converted to heat. Engineering analyses are needed to size flow hardware to ensure...
01:28
Plasmids
0 Views •
2025
Plasmids are extrachromosomal DNA molecules found in bacteria, archaea, and some eukaryotic microbes like yeast. These small, circular DNA structures typically contain fewer than 30 genes, although some may exist linearly. Plasmids vary in their number within a cell, known as copy number. Single-copy plasmids are present in one copy per cell and multi-copy plasmids are present in multiple copies, reaching over 100 copies per cell.Plasmids usually replicate independently of the chromosomal DNA...
07:11
Homemade Site Directed Mutagenesis of Whole Plasmids
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Cited by 91 •
2009
Site directed mutagenesis of whole plasmids is a simple way to create slightly different variations of an original plasmid. Here we demonstrate an easy and cost effective way to introduce base substitutions into a plasmid using standard reagents.
FAQs
Plasmid maintenance depends on both accurate replication and effective partitioning during cell division. Replication produces plasmid copies, while partitioning helps distribute those copies between daughter cells. A defect in either process increases the chance that one daughter receives no plasmid. Distinguishing these mechanisms helps researchers interpret instability and identify whether copy production or cellular distribution is the main concern.
Without antibiotic or another selective pressure, cells do not receive a growth advantage from retaining the plasmid. Plasmid-free cells can therefore persist during culture, while repeated divisions dilute plasmid-bearing lineages across successive generations. Comparing cultures maintained with and without selection reveals how strongly environmental conditions favor plasmid retention and can expose instability that selection otherwise masks.
Even a low probability of imperfect replication or partitioning can produce plasmid-free progeny during individual divisions. Those progeny continue growing and dividing, so their proportion can increase over time, particularly when no selection favors plasmid-bearing cells. The cumulative pattern makes generation number and culture history important variables when evaluating genetic stability.
Researchers can follow the proportion of plasmid-bearing cells as a culture grows through successive generations, especially under conditions with or without selection. Comparing the starting and later proportions provides an estimate of loss over time and supports calculation of a loss rate. Repeated measurements help distinguish gradual instability from a pronounced change during a particular growth interval.
Monitoring is important when a plasmid carries a system intended to produce a genetic product, because loss of the plasmid can reduce the fraction of cells retaining that system. Cultures may then become less uniform as plasmid-free progeny accumulate. Measuring stability under the intended growth conditions helps researchers judge whether observed performance can be maintained over time.
Loss measurements provide a practical indicator of how stably a vector persists in a cell population. Researchers can use that information to guide the development of vectors with improved maintenance and to compare culture conditions that favor retention. In microbial biology, the same analysis helps examine how mobile genetic elements persist or decline across generations.