Concept explainers
To analyze:
The steps of biochemical pathway showing the sequence of different compounds and enzymes on the basis of the given data.
Given:
Bacterial strains mutated for five different enzymes (1, 2, 3, 4, and 5) were grown on a variety of media, which was substituted with different compounds involved in the pathway. Table 1 represents the mutant strain growth on the medium having different compounds required in the biochemical pathway.
Table 1: Growth of different mutants on medium containing different compounds of the biochemical pathway.
In the table shown above, compound ‘C’ or chorismate is the precursor in the biochemical pathway and ‘T’ or tryptophan is the end product. Compound D, E, F, and G are intermediates. The ‘+’ represents growth when the indicated compound was added to the growth medium, and ‘0’ represents the absence of growth.
Introduction:
In a wild-type bacterium, the synthesis of tryptophan takes place through a series of enzymatic reactions starting from the precursor, chorismate. In this experiment, to deduce the biochemical pathway, the bacterial strains have been mutated for different enzymes and the growth of the bacteria in presence of different compounds has been recorded.
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Life: The Science of Biology
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- Clary Leonhart used the pET vector system to express her prokaryotic amylase enzyme. She added peptone into her culture broth of BL21 (DE3) Escherichia coli strain. At the end of the experiment, she discovered that her protein was not expressed. She repeated three more times but her protein of interest was still not produced. (i) (ii) Explain the reason why Clary failed to obtain her protein of interest and suggest a solution to troubleshoot this problem. Clary plans to express her protein along with a polyhistidine-tag, or better known by its trademarked name IIis-tag. Explain the importance of His-tag in protein work.arrow_forwardA classic way to isolate thymidylate synthase-negative mutants of bacteria is to treat a growing culture with thymidine and trimetho- prim. Most of the cells are killed, and the survivors are greatly enriched in thymidylate synthase-negative mutants. (a) What phenotype would allow you to identify these mutants? (b) What is the biochemical rationale for the selection? (That is, why are the mutants not killed under these conditions?) (c) How would the procedure need to be modified to select mam- malian cell mutants defective in thymidylate synthase?arrow_forwardA classic way to isolate thymidylate synthase-negative mutants of bacteria is to treat a growing culture with thymidine and trimethoprim. Most of the cells are killed, and the survivors are greatly enriched in thymidylate synthase-negative mutants. (a) What phenotype would allow you to identify these mutants? (b) What is the biochemical rationale for the selection? (That is, why are the mutants not killed under these conditions?) (c) How would the procedure need to be modified to select mammalian cell mutants defective in thymidylate synthase?arrow_forward
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