Consider an experiment where wild-type E. coli , the Trp codon mutant (UGG codon
ID: 41511 • Letter: C
Question
Consider an experiment where wild-type E. coli, the Trp codon mutant (UGG codons mutated to GGG), and the region 3 mutant (deletion of region 3) are grown separately in media that is abundant in all necessary nutrients and amino acids, except tryptophan. Label the 7 statements below with one of the three statments shown here.
The following statements are related to the information presented above. Based on the information given above, select one for each of the 7 statments:
A. if the statement is supported by the information given
B. if the statement is contradicted by the information given
C. if the statement is neither supported nor contradicted by the information given
-------------------------------------------------------------------------------------------------------------
1) _____ Trp codon mutant cells die.
2) _____ Wild-type cells grow the fastest.
3) _____ Region 3 mutant cells grow the slowest under such conditions.
4) _____ Chromosome-polysome complexes form on the Trp operon in all 3 cells.
5) _____ Tryptophan is synthesized in significant quantities in region 3 mutant cells only.
6) _____ Using a trp leader DNA fragment as a probe, Northern blot analysis of cellular RNA in trp codon mutants identifies a strong band corresponding to a 140-nucleotide RNA. **Note, Northern blots detect the size of RNA fragments with sequences complementary to the probe.
7) _____ Using the same probe, a large amount of full length trp operon transcripts (no attenuation) are detected in wild-type cell RNA samples.
Explanation / Answer
A. supported by information given: 1. because not trp cells will die. 2. wild type will grow fast because they can make trp. 6. & 7 is supporting
B. contradicting the information: 3. because region 2 will not have region 3 for pairing so cells will not grow only. 5. is condracting,
C.statement which is neither contradicting nor supporting.4.