(SHOW WORK): You are studying gene expression from the lac operon in E. coli . W
ID: 46690 • Letter: #
Question
(SHOW WORK): You are studying gene expression from the lac operon in E. coli. Wildtype lac mRNA is approximately 5kb in length. Two kinds of lacZ and lacYmutations are studied. The lacZ- and lacY- mutations are simple nucleotide substitutions that encode inactive proteins. The lacZ* and lacY* mutations are deletions. The lacZ* deletion is missing 2kb of lacZ coding sequence, lacY* is missing 0.5kb of lacY coding sequence, and neither allele produces a polypeptide product. For each of the following genotypes, indicate the size(s) of the mRNA transcripts that would be produced in the presence AND in the absence of lactose. Then, indicate whether b-galactosidase and/or permease protein would be made in the presence AND in the absence of lactose.( Answer for A, B, C and D)
A. F lacI+ lacOc lacZ* lacY- / lacI+ lacO+ lacZ- lacY*
B. F lacI- lacO+ lacZ* lacY- / lacI+ lacO+ lacZ- lacY*
C. lacI+ lacO+ lacZ* lacY*
D. F lacI+ lacO+ lacZ+ lacY* / lacI+ lacO+ lacZ* lacY*
Explanation / Answer
Genotype
Size of mRNA transcripts
Presence of b-galactosidase and/or permease protein
Reason
A. F
Genotype
Size of mRNA transcripts
Presence of b-galactosidase and/or permease protein
Reason
A. F
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