Bio151 Sp13 Exam 3 answer key

The preferred energy source of the cell is glucose

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Unformatted text preview: diagram of the lac I gene and lac operon for questions 17and 18. (I = lac repressor gene; Z, Y, A = lac operon structural genes; P = promoter for lac I gene or for lac operon; O = lac operator) PO Z Y A PI D17. Where would the lac repressor be bound in a (nonmutant) E. coli cell that is growing in low glucose and high lactose? a. P b. O c. P and O d. The repressor would not be bound D18. Which parts of the DNA region shown in the diagram encode proteins? a. P 3 Bio151 Sp13 Name: Exam 3 Prof. Francis Discussion Section number or TA’s name or DS day/time: b. Z, Y, A c. P, O, Z, Y, A d. I, Z, Y, A e. I, P, O, Z, Y, A Questions 19- 23 The gene for human growth factor is inserted into the E. coli lactose operon so that it replaces the structural genes with the gene for the human growth factor. Which of the following substances added to the bacterial culture would lead to production of human growth factor? A = Yes; B = No A19. Lactose B20. Human growth factor B21. Xgal A22. IPTG B23. LacI Open Response questions Question 1 (4 pts) Explain why it is necessary to regulate expression of the Lac operon genes according to both the level of lactose and the level of glucose in the cell. The lactose operon synthesizes products that metabolize lactose, thus allowing lactose to serve...
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This note was uploaded on 01/21/2014 for the course BIO 151 taught by Professor Randallphillis during the Fall '12 term at UMass (Amherst).

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