Cloning w/ Plasmid DNA: AmpR Gene Overlap Issue

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SUMMARY

The discussion centers on the cloning process involving plasmid DNA and the potential issue of the AmpR gene being overlapped by a restriction site for inserting a gene of interest. It is established that cutting the plasmid at the restriction site can deactivate the Ampicillin resistance, complicating the selection of transformed bacteria. However, the use of replica plating allows for the identification of colonies that have successfully taken up the plasmid with the gene of interest, distinguishing them from those that have not. This method relies on the presence of additional antibiotic resistance genes on the plasmid to facilitate selection.

PREREQUISITES
  • Understanding of plasmid DNA structure and function
  • Knowledge of restriction enzymes and their applications in cloning
  • Familiarity with antibiotic resistance mechanisms, specifically Ampicillin resistance
  • Experience with replica plating techniques in microbiology
NEXT STEPS
  • Research the mechanics of restriction enzyme digestion and its impact on plasmid functionality
  • Learn about alternative antibiotic resistance genes that can be used in plasmid design
  • Study the principles and applications of replica plating in bacterial selection
  • Explore methods for verifying successful gene insertion in plasmids, such as PCR or sequencing
USEFUL FOR

This discussion is beneficial for molecular biologists, genetic engineers, and students involved in cloning experiments who need to understand the implications of plasmid design and selection strategies in bacterial transformation.

plexus0208
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Homework Statement


I have a problem that involves a plasmid DNA. The problem gives a plasmid diagram with the restriction sites and specifically tells me which restriction site the gene of interest would go. However, the restriction site is shown to be overlapping with the AmpR gene. Wouldn't that mean the Ampicillin resistance is deactivated when the restriction enzyme cuts the site? I don't get how the gene is supposed to be amplified in bacteria if the plasmid doesn't have AmpR...

Homework Equations


Biology - none

The Attempt at a Solution


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Hello!
I think the process you are referring to is replica plating. It allows you to keep the colonies that you have produced in the experiment, whilst checking for certain genotypes. Some bacteria may take up the plasmid but not the recombinant form containing a gene of interest, by placing it within an antibiotic resistance gene, it inactivates that gene. There will be other resistant genes also present on the plasmid, and yopu can check the colonies against a number of antibiotics; this two step process allows you to distinguish between bacteria that have taken up the plasmid from those that haven't, determined by a functioning resistance gene on the plasmid that is not disrupted by restriction endonucleases; and then the colonies formed from the bacteria of interest (those with a plasmid that have incorporated a gene of interest) can then be distingiushed from those that have taken up a plasmid but do not contain the gene of interest, as those that have not taken up the gene of interest will be resistant to the second type of antibiotic, but the those of interest will not be resistant. Remember, replica plating does not destroy the colony of bacteria!
I think this is right, I hope it helps.
 
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