Answer #1,2,3,4, and 5. Lactose Operon: An Active Learning Approach Amy Mulnix D
ID: 222626 • Letter: A
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Answer #1,2,3,4, and 5.
Lactose Operon: An Active Learning Approach Amy Mulnix Department of Biology arlham College Richmond, Indiana 47373 tion, DNA-protein interactions, allosteric regular INTRODUCTION Interest in alternatives to the traditional lec tion of DNA-protein interactions. The objective of ture format has been on the rise. Active- and the exercise is to have students deduce the model group-learning approaches attempt to draw stu for the regulation of the lac operon from summary dents into purposeful interaction with the materi statements of observations about the system. al, the faculty member and with each other. At Students work in small groups (3 or 4) to answer a their best, these approaches can bring the student series of questions, modify a diagram, and com past memorization to understanding, synthesis plete a table in response to the statements. The and application of the material. Other advantages exercise that the student groups are given follows. of these techniques include giving the student a larger responsibility for his/her own learning pro EXERCISE cess and practice in interpersonal skills. Directions: Each of the following statements is an I have attempted to introduce a variety of pre- observation of the lactose utilization system in sentation formats into our sophomore Cell Eshericia coli. Read each statement carefully and Biology course. Many of these take a hands-on, identify the appropriate feature on the diagram exercise intro- provided (see Figure 1). Discuss the answers to interactive approach. One such duces the central concepts of prokaryotic gene the questions posed, making your own notes as regulation: polycistronic genes, repression, activa necessary. If a term or concept (especially one in regulatory region lac operon. laci gene operon DNA mRNA repressor B-gal Permease transacetylase lactose allolactose Figure 1. Regulation of the lac operon. A diagram similar to this is drawn on newsprint paper (18" x 24". Color markers are used to distinguish between DNA, RNA and protein. Student groups are provided with markers or crayons and are encouraged to alter the diagram with arrows, numbers, and phrases to indi- cate the regulatory mechanisms.Explanation / Answer
1. First beta GAL, second permease and third transacetylase will transcribed in this order. when lactose is not present the structural genes will not transcribed. In the absence of lactose, the repressor will bind to operator and will not allow the Polemerase to move.
2. RNA polemerase is binding to the promoter and repressor is binding to the operator, since these two sites are overlapping you can say that they can bind to the control region simultaneously.
3.Lac repressor will bind to the operator when lactose is not present that is why lac operon genes will not transcribed in this condition.
4. When lactose is present, the allolactose will form and this allolactose will bind to the allosteric site of the repressor and changing its ability to bind to the operator thus allowing RNA polymerase, which is bound to the promoter, to transcribe the lac operon genes. in the presence of lactose repressor will not bind to the operator. yes polemerase will be bound to the promoter when lactose is present.