Activity week 9 answers

Activity week 9 answers - Repressor Operator mRNA a....

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Name: Section Time: Bis2A Activity Week 9 1. The genes that produce the amino acid tryptophan in E. coli are organized into an operon. In the absence of tryptophan in the growth medium, these genes are turned on. In the presence of tryptophan in the growth medium, they are turned off. Using the concepts of repressors, operators, and promoters, describe a mechanism by which tryptophan could turn off these genes. Which of the lines in the table below describes the status of the cell when high concentrations of tryptophan are present? Repressor Operator mRNA a. present- not active open present b. present- not active open not present c. present- active blocked present d. present- active blocked not present e. not present- not active open present f. not present- not active open not present 2. Conversely, the operon for the utilization of lactose is set up so that its genes are turned on only in the presence of lactose. Which of the lines in the table below describes the status of the cell when high concentrations of lactose are present?
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Unformatted text preview: Repressor Operator mRNA a. present- not active open present b. present- not active open not present c. present- active blocked present d. present- active blocked not present e. not present- not active open present f. not present- not active open not present 3. You are able to isolate and determine the sequence of the mRNA for a protein. After much effort, you also isolated the gene (the chromosomal DNA containing the template sequence for the mRNA) and determined its sequence. In comparing the sequences, you found that the gene was 3 times as long as the mRNA. Then you wrote your PH.D. thesis. Which of the following statements might have been found in your discussion? a. The protein was found in E. coli (bacterial) cells b. The gene has 4 introns and 5 exons c. The gene has 4 introns and 4 exons d. Several separate RNA molecules must have been joined to make the mRNA e. There is no way to explain the data...
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Activity week 9 answers - Repressor Operator mRNA a....

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