For each of the E. coli strains below, determine the effect ofthe genotype on expression of the trpE and trpC genes in thepresence and absence of tryptophan. In the wild-type strain(genotype: R+ P+ O+ att+ trpE+ trpC+), the trpE and trpC genes arefully induced in the absence of tryptophan and fully repressed inthe presence of tryptophan.
Key:
R = functional repressor gene; Rn = product cannot bind tryptophan;R- = product cannot bind operator
O = functional operator; O- = operator cannot bind repressorprotein
att = functional attenuator; att- = a deletion of the attenuatorsequence
P = functional promoter; P- = a deletion of the trp operonpromoter
trpE- and trpC- = produce non-functional protein products
1) R+ P- O+ att+ trpE+ trpC+
2) R- P+ O+ att+ trpE+ trpC+
3) Rn P+ O+ att+ trpE+ trpC+
4) R- P+ O+ att- trpE+ trpC+
5) R+ P+ O- att+ trpE+ trpC- / R- P+ O+ att+ trpE- trpC+
6) R+ P- O+ att+ trpE+ trpC- / R- P+ O+ att+ trpE- trpC+
7) R+ P+ O- att- trpE+ trpC- / R- P+ O- att+ trpE- trpC+
- 1. 2. 3. 4. 5. 6. 7.
Trp = trpE (-), trpC (-); No Trp = trpE (+), trpC (+)
- 1. 2. 3. 4. 5. 6. 7.
Trp = trpE (-), trpC (-); No Trp = trpE (+), trpC (+)
- 1. 2. 3. 4. 5. 6. 7.
Trp = trpE (-), trpC (-); No Trp = trpE (-), trpC (-)
- 1. 2. 3. 4. 5. 6. 7.
Trp = trpE (-), trpC (-); No Trp = trpE (-), trpC (+)
- 1. 2. 3. 4. 5. 6. 7.
Trp = trpE (+), trpC (-); No Trp = trpE (+), trpC (+)
- 1. 2. 3. 4. 5. 6. 7.
Trp = trpE (+), trpC (+); No Trp = trpE (+), trpC (+)
- 1. 2. 3. 4. 5. 6. 7.
Trp = trpE (-), trpC (-); No Trp = trpE (+), trpC (+)
For each of the E. coli strains below, determine the effect ofthe genotype on expression of the trpE and trpC genes in thepresence and absence of tryptophan. In the wild-type strain(genotype: R+ P+ O+ att+ trpE+ trpC+), the trpE and trpC genes arefully induced in the absence of tryptophan and fully repressed inthe presence of tryptophan.
Key:
R = functional repressor gene; Rn = product cannot bind tryptophan;R- = product cannot bind operator
O = functional operator; O- = operator cannot bind repressorprotein
att = functional attenuator; att- = a deletion of the attenuatorsequence
P = functional promoter; P- = a deletion of the trp operonpromoter
trpE- and trpC- = produce non-functional protein products
1) R+ P- O+ att+ trpE+ trpC+
2) R- P+ O+ att+ trpE+ trpC+
3) Rn P+ O+ att+ trpE+ trpC+
4) R- P+ O+ att- trpE+ trpC+
5) R+ P+ O- att+ trpE+ trpC- / R- P+ O+ att+ trpE- trpC+
6) R+ P- O+ att+ trpE+ trpC- / R- P+ O+ att+ trpE- trpC+
7) R+ P+ O- att- trpE+ trpC- / R- P+ O- att+ trpE- trpC+
- 1. 2. 3. 4. 5. 6. 7.
Trp = trpE (-), trpC (-); No Trp = trpE (+), trpC (+)
- 1. 2. 3. 4. 5. 6. 7.
Trp = trpE (-), trpC (-); No Trp = trpE (+), trpC (+)
- 1. 2. 3. 4. 5. 6. 7.
Trp = trpE (-), trpC (-); No Trp = trpE (-), trpC (-)
- 1. 2. 3. 4. 5. 6. 7.
Trp = trpE (-), trpC (-); No Trp = trpE (-), trpC (+)
- 1. 2. 3. 4. 5. 6. 7.
Trp = trpE (+), trpC (-); No Trp = trpE (+), trpC (+)
- 1. 2. 3. 4. 5. 6. 7.
Trp = trpE (+), trpC (+); No Trp = trpE (+), trpC (+)
- 1. 2. 3. 4. 5. 6. 7.
Trp = trpE (-), trpC (-); No Trp = trpE (+), trpC (+)
Related textbook solutions
Related questions
For this question, focus on four parts:
I, the gene that produces the repressor protein;
P, the promoter region where RNA polymerase binds to initiate transcription;
O, the Operator site, where the repressor binds. When the repressor binds, it prevents transcription; and
ZYA, the three structural genes, all of which are required for the successful utilization of lactose as a food source.
In the left column of the table below, we indicate the genetic composition at the lac operon of particular strains of E. coli cells. A "+" (plus sign) following the letter indicates the wild-type allele (or normally functioning version of the gene). For I, P, and ZYA, a "-" (negative sign) following the letter indicates the mutant allele (or non-functional version of the gene). For the O allele, a "C" indicates the mutant or constitutive allele. It is not functional in that the repressor cannot bind, but it is functional in that transcription can still occur.
Given the conditions stated in each column, please indicate for each genotype whether lac mRNA is produced and at what level by typing in one of the following words in each cell in the table:
"Abundant"
"Minimal"
"None"
The completely wild-type genotype has already been filled in.
| Cellular conditions: | |||
| Genotype | Glucose present (low cAMP) and no lactose | Glucose present (low cAMP) and lactose present | No glucose (high cAMP) and lactose present |
| I+ P+ O+ ZYA+ | None | Minimal | Abundant |
| I- P+ O+ ZYA+ | |||
| I+ P- O+ ZYA+ | |||
| I+ P+ Oc ZYA+ | |||
| I+ P+ O+ ZYA- | |||
