An e coli strain acquires a mutation in its lac

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An E. coli strain acquires a mutation in its lac repressor gene (lacI); the mutated LacI repressor protein has changed such that it will not bind to the lac operator sequences under any circumstances. As a result, this strain will never be able to grow on lactose. A) True B) False Question 22 Your answer is INCORRECT. The stringent response involves all EXCEPT : A) reduction in ribosomal RNA synthesis B) stalled ribosomes and uncharged tRNAs C) nutrient-poor conditions D) ppGpp E) all are involved Question 23 Your answer is CORRECT. Which of the following explains the regulatory activity of small RNA (sRNA) genes? A) It codes for a sigma factor. B) It prevents CRP interaction with RNA polymerase, thereby blocking its access to the promoter. C) It synthesizes ppGpp. D) It targets mRNAs for degradation or blocks ribosome binding to mRNAs. E) It creates an attenuator stem loop. Question 24 Your answer is CORRECT. Which of the following is not true of phase variation? A) The DNA sequence is not altered or changed. B) It may help the bacteria avoid the immune system. C) It requires recombination. D) It affects external structures of the bacterium, like the flagellum, capsule, or fimbriae. E) All are true Question 25 Your answer is CORRECT. Which of the following statements is false ? A) Constitutive genes are always expressed. B) The activity of a quorum-sensing gene system is proportional to the cell density of the population. C) A feature common to all control mechanisms is the ability to sense that something inside or around the cell has changed. D) In chemotaxis, the addition or removal of phosphate from Che-Y protein determines whether bacterial motion is tumbling or smooth runs. E) None are false; all are true statements. Question 26 Your answer is INCORRECT. Which of the following are likely to favor G values that are more negative? A) an increase in reactants over products B) forming products that are simpler and greater in number than the reactants C) formation of products that are more stable and have less energy than the reactants D) forming products that have higher entropy (positive delta S) than the reactants E) all the above favor negative G values. Question 27 Your answer is CORRECT.
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Formation of concentration gradients is a common feature among microbes and all cells. Which of the following is false regarding concentration gradients? A) It requires energy to produce the gradient. B) The gradient can be used to do work. C) Movement of molecules down a gradient releases energy. D) Entropy decreases as molecules diffuse down their gradient. E) None are false; all are true. Question 28 Your answer is CORRECT. Which of the following statements is false regarding the electron donors in bacterial and archaeal metabolism? A) The use of organic compounds as electron donors is known as organotrophy. B) Glucose would be a suitable electron donor for lithotrophs.
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