Usually, bacteria only make tryptophan when tryptophan is absent or available in low concentration. However, a particular bacterial mutation makes tryptophan all the time whether or not tryptophan is present. What could explain this phenotype?
A) trpA is mutated
B) trpE is mutated
C) trpD is mutated
D) the antiterminator hairpin is unable to form
E) the terminator hairpin is unable to form
Answer: E
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Sexual reproduction
A. allows more offspring to be produced per individual. B. allows a parent to pass on 100% of their genes to offspring. C. increases genetic variation. D. results in the formation of a haploid zygote. E. only occurs in vertebrates.
The respiratory surfaces of mammalian lungs are called ____
a. alveoli b. bronchi c. tracheae d. bronchioles e. air sacs
Recombination involves the breakage and reunion of DNA molecules from
A) homologous nonsister chromatids. B) homologous sister chromatids. C) heterologous nonsister chromatids. D) heterologous sister chromatids.
What part of the squid is homologous to the snail foot?
A. Fins B. Mantle C. Beak D. Tentacles