Lacž apha 21. At right is a plasmid map that provides a template for homologous
ID: 214333 • Letter: L
Question
Lacž apha 21. At right is a plasmid map that provides a template for homologous recombination following Cas-9 cleavage in C. elegans. (1 point) Put a star by any sequences that can be expressed as a protein in E. a. coli. sel-11 RepairTemplate Key: Rps-27: ribosomal protein, (small subunit) 27 Myo-2: pharynx-specific muscle myosin b. (1 point) Put arrows by any sequences that would be expressed as proteins after homologous recombination in C. elegans (2 points) Explain what expression pattern you would expect for your gene(s) from part B. c. t are grown in the presence of X-gal and IPTG, will the (2points) If t resulting colonies be blue or white? Why? d. his plasmid is transformed into E. coli thaExplanation / Answer
a) The only protein that will be expressed in E.coli is the protein encoded by the Amp (yellow) gene. This gene encodes for a protein that confers the bacteria resistance against the antibitoic ampicilin.
b) In C. elegans, the proteins encoded downstream of the promoter Myo-2 (green) and Rps-27 (light blue) will be expressed.
c) If this plasmid is transfered into C elegans, 2 gene mRNAs will be generated. One will will be from the promoter Myo-2 which when translated will produce a GFP. The other is from the Rps-27 promoter. The gene products is difficult to. make out due to bad image quality.
d) If this plasmids is trasnfomed in to E. coli and grown in the presence of X-gal and IPTG, the resulting colonies will be all white.
While constructing the plasmid, the insert of choice is inserted into the multiple cloning site present on the LacZ gene. Thus in this plasmid , the LacZ gene is inactive.
If the LAcZ gene is active, the gene product could break down Xgal and produce a product which is blue in colour. Hence colonies that carry the plasmid with out the insert would appear blue.
If an insert is present, the lacZ zgene is inactive, hence the protein is not made and blue color is not fomed. Therefore the colonies appea white.
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