What do you predict would happen if you replace the Lac operator DNA from the Lac operon with the DNA from the operator region from the tryptophan operon?
(a) The presence of lactose will not cause allosteric changes to the Lac repressor.
(b) The Lac operon will not be transcribed when tryptophan levels are high.
(c) The lack of glucose will no longer allow CAP binding to the DNA.
(d) RNA polymerase will only bind to the Lac promoter when lactose is present.
(b) Replacing the Lac operator with the tryptophan operon operator will now allow binding of the tryptophan repressor instead of the Lac repressor. Since the tryptophan repressor binds to DNA when tryptophan levels are high, the tryptophan repressor is predicted to block mRNA production from the Lac operon when tryptophan is abundant in the cell. Changing the operator sequences at the Lac operon should not affect how the presence of lactose changes the Lac repressor [choice (a)], nor should it affect the ability of CAP to bind to the DNA at low glucose levels, since the CAP-binding site is on the other side of the RNA polymerase binding site [choice (c)]. Removing the Lac operator will make it so that the Lac promoter is no longer responsive to lactose levels in the cell [choice (d)].
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After a restriction enzyme cuts DNA into fragments and the fragments pair with complementary bases, the enzyme
____________________ is used to seal the gaps in the phosphate backbone. Fill in the blank(s) with the appropriate word(s).
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Which of the following statements regarding mitosis and meiosis is true?
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