Below is a schematic map of a hybrid gene constructed from elements of the lac a
ID: 40373 • Letter: B
Question
Below is a schematic map of a hybrid gene constructed from elements of the lac and trp operons. In words, the CAP binding site amd promoter from the lac operon have been fused to the operator and transcribed sequence from the trp operon. This is one of those hybrid systems in which components from different genes will each act autonomously.
This hybrid gene was transformed into a series of mutant E. coli hosts, and the expression of the trpA gene product was measured. All of the hosts were derived from a strain that had its normal trp operon deleted so the only possible source of trpA enzyme is the hybrid gene. In the table below, the genotype of the host is to the left, and additions to the medium are across the top. Use pluses or minuses to indicate whether the trpA enzyme will be produced by each genotype under each of the conditions. The basic incubation conditions were minimal medium with glycerol as the carbon source. CAP is the gene for the cataolite activator protein, trpR^(s) is a mutant of the trp repressor that binds to the operator regardless of tryptophan concentrations, and CAP^(S) is a mutant of the CAP protein that binds to the CAP site in the regardless of glucose concentration:
trp operon
Below is a schematic map of a hybrid gene constructed from elements of the lac and trp operons. In words, the CAP binding site amd promoter from the lac operon have been fused to the operator and transcribed sequence from the trp operon. This is one of those hybrid systems in which components from different genes will each act autonomously. This hybrid gene was transformed into a series of mutant E. coli hosts, and the expression of the trpA gene product was measured. All of the hosts were derived from a strain that had its normal trp operon deleted so the only possible source of trpA enzyme is the hybrid gene. In the table below, the genotype of the host is to the left, and additions to the medium are across the top. Use pluses or minuses to indicate whether the trpA enzyme will be produced by each genotype under each of the conditions. The basic incubation conditions were minimal medium with glycerol as the carbon source. CAP is the gene for the cataolite activator protein, trpR^(s) is a mutant of the trp repressor that binds to the operator regardless of tryptophan concentrations, and CAP^(S) is a mutant of the CAP protein that binds to the CAP site in the regardless of glucose concentration:Explanation / Answer
The trp operon a group of genes that are used, or transcribed, together ,that codes for the components for production of tryptophan.The tryptophan (Trp) operon is inhibited by tryptophan This operon contains five structural genes: trp E, trp D, trp C, trp B, and trp A, which encode for the enzyme trptophan synthase. a promoter region where RNA polymerase binds to a repressor trpR which synthesizes a specific protein. The protein that is synthesized by trp R then binds to the operator which then causes the transcription to be blocked. the trp operon also consists of the attenuator sequence ,which stops the operon.
genotype trpR + cap+
presence of trytophan ; represses the operon , presence of glucose cause the inhibhition of operon , both trptophan and glucose are inhibitors .
GENOTYPE TRP R- AND CAP+;
Presence of trptophan ; no effect on the operon , presence of glucose causes he inhibition of operon , both trp and glucose act as inhibitors but as the trptophan regulatory gene is absent trptophan operon continues to produces enzyme but lac operon is stopped
GENOTYPE TRP R + AND CAP -
THIS CAUSES the in the presence of trptophan the operon to operate ,causes the inhibhition of operon , in presence of both glucose and trptophan , still it operates causing the operon to inhibit becaus eof trptophan
GENOTYPE TRPs ,CAP+ ;
PRESENCE OF tryptohan no effect , as there is mutation in trpR gene . presence of glucose causes the inhibition of operon . in the presence of gulcose and tryptophan causes the inhibhition of operon.
GENOTYPE TRP Rs , CAP-;
NO EFFECT ON THE OPERON AS THE TRPR S GENE IS MUTATED AND CAP GENES IS ABSENT
GENOYPE TRP+ AND CAP s;
mutation in the CAP PROTEIN CAUSES THE LAC OPERON TO CONTINUE , BUT PRESENCE OF TRPTOPHAN CAUSES THE INHIBHITION OF OPERON , BUT IN THE PRESENCE OF GLUCOSE AND TRYPTOPHAN CAUSES THE INHIBHITON OF THE OPERON BECAUSE OF TRYPTOPHAN.
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