Operon Worksheet Name: _______________________Date ________T#: _________ 1. Unde

Question

Operon Worksheet Name: _______________________Date ________T#: _________

1. Under what circumstances would the lac operon be “on” versus “off”? How is this different from the trp operon?

2. How are the lac and trp operons similar (in structure and function)? 3. What are the key differences between the lac and trp operons?
4. What are the advantages of having genes organized into operons?

5. You are working with a strain of E. coli that has a mutated and non-functional lac regulatory gene in its genome. You add a plasmid to these cells containing a normal lac operon and normal lac regulatory genes.
a. Draw a diagram of the modified bacterial cell. Label all important parts.

b. Before the addition of the plasmid, would the E. coli mutants be able to produce the enzymes for lactose digestion? Explain your answer.

c. After the addition of the plasmid, would the plasmid’s lac operon produce the enzymes for lactose digestion constitutively or on only when lactose was the available sugar source. Explain your answer.

d. After the addition of the plasmid, would the bacterial genome’s lac operon produce the enzymes for lactose digestion constitutively or only when lactose was the available energy source? Explain your answer.

Safari File Edit View History Bookmarks Window Help mytsu.tnstate.edu mytsu tn state.edu/cpigrouptoo... SunGard Higher Ed Watch TV On operon Worksheet Name TR ate Fill in the chart to organize what you know about the lac and trp operons. Operon: Briefly explain the purpose of each of pathways that the involved in. Are the pathways What regulatory Genes: Functions: associated with the operon, and what functions does each What structural genes are included in each operon and what does each Is the repressor protein produced in an active or inactive What conditions are necessary for the repressor protein to become active? Chegg Study l Guided Solutio... 72% Wed 12:53 AM Lab10b-DATA-PRACTICE. a Layout References Mailings Review 12 A A A abe X2 x ing the modes of inheritance of mutant This unit is one of the hierarchy of B IR

Explanation / Answer

Ans 1. The lac repressor and catabolite activator protein (CAP) arethe two regulators that turn the operon "on" and "off" in response to lactose and glucose levels.The trp operon is an example that controls a anabolic pathway whereas lac operon controls a catabolic pathway.

Ans 2. The lac operon consists of lac Z, lac Y, lac A, as structural genes, and a promoter, a terminator, regulator, and an operator. The cluster of genes responsible for lactose transportation and metabolism in E.coli bacteria is lac operon. Trp operon is required for Trp synthesis. The Lac operon has one promoter region The operon is activated by the presence of lactose. The trp operon also contains trp R that produces a repressor when needed.The operon consists of trp E, trp D, trp C, trp B, and trp A, which is refered as tryptophan synthetase collectively. The key difference is that the Lac operon is involved in the catabolic process of a sugar, However, Trp operon is involved with the anabolic process of an amino acid.

Ans 4. A group of functionally related enzymes is produced from a single mRNA transcript.

Ans 5.(a) refer any book

         (b) Yes, possible by replacing glucose moiety of lactose by another chemical group. for eg Isopropyl--D-thiogalactoside (IPTG) can be used as an inducer of the lac operon for physiological work. It function by binding to repressor and inactivates it.

(c) (d) lac operon gene is turned off by the regulatory factor unless some lactose is added. Thus it produces only when lactose was the available as a sugar source.

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