Question #3 You transform bacteria with the ligation products.The bacteria are t
ID: 13913 • Letter: Q
Question
Question #3
You transform bacteria with the ligation products.The bacteria are then grown on LB + ampicillin + X-gal.
Fill in the following table describing the colonies that result from transformation of bacteria by each of the recombinant DNAs. table for question #3 here http://www.scribd.com/doc/68877766/Homework-3-F11
Total size of ligated DNA
Grows on ampicillin? (Y/N)
Blue or White? (B/W)
Total size of ligated DNA
Grows on ampicillin? (Y/N)
Blue or White? (B/W)
Explanation / Answer
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The medium contains the following three components:
LB (Luria broth) is the rich medium E.coli needs to grow
ampicillin is the antibiotic that kills E.coli bacteria that have not been successfully transformed with the pUC19 vector. The pUC19 vector includes the constitutively expressed gene AmpR that codes for the enzyme beta-lactamase that confers ampicillin resistance to the bacteria.
X-gal is a saccharide that turns blue when it is broken down by the enzyme beta-galactosidase. That enzyme is expressed by the gene LacZ present on pUC19. When the gene LacZ is disrupted by inserting a fragment in it, then it no loungers produces the functional enzyme beta-galactosidase, hence why the colony stay white.
Total size of Grows on ampicillin? Blue or White?
ligated DNA
2666 bp Yes Blue
4167 bp Yes White
5667 bp Yes White
The ligated DNA that is listed last (5667 bp) is pUC19 + TWO 1.5 kb fragments inserted in it. This may happen, rarely :)