1If a protein is described as a positive regulator of a gene or genes, a. there

Question

1If a protein is described as a positive regulator of a gene or genes, a. there is no transcription of the gene or genes if the protein is bound to DNA b. there is transcription of the gene or genes if the protein is bound to DNA c. the protein produces a small molecule called the inducer d. the protein produces a small molecule called the repressor

2. What term describes the expression of ?-galactosidase of the lac operon in a strain of Escherichia coli with a mutation in the repressor gene abolishing the ability of the repressor to bind to the operator? A. Inducible B. Constitutive C. Never expressed

3. What term describes the expression of ?-galactosidase of the lac operon in a strain of Escherichia coli with a mutation in the operator gene abolishing the ability of the repressor to bind to the operator? A. Inducible B. Constitutive C. Never expressed

4. Which of the following features are common to both positively and negatively acting regulatory proteins? A. Bind to DNA and a small molecule from the intra- or extra-cellular environment B. Degrade the inducer C. Like sigma protein, bind to RNA polymerase D. Bind directly to mRNA

5. What is the role of cyclic AMP (cAMP) in the regulation of expression of the lac operon? A. No role, cAMP is not involved in regulation of the lac operon B. cAMP prevents transcription, like the repressor and positive regulatory protein C. cAMP is required for transcription, in conjunction with the catabolite activating protein (CAP) D. cAMP binds to lactose to repress transcription E. cAMP is required for translation

Explanation / Answer

Ans. 1 C the protein produce small molecule called inducers. In E. Coli the inducer molecule of lactose.

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