When a repressor binds to the operator site on the DNA it normally
A. inhibits the initiation of transcription.
B. has no effect on transcription.
C. terminates transcription that has already been initiated.
D. reduces the rate of transcription.
Answer: A
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Membrane potential is determined by:
A. the number and types of proteins present in the plasma membrane of a cell. B. the difference in concentration of ions and charged molecules across the plasma membrane of a cell. C. the number and type of phospholipids present in a membrane. D. the concentration of cholesterol in a membrane.
A molecular biologist is interested in purify a recombinant protein by His-tagging, but the protein and vector both lack histidine residues. In this case, the molecular biologist could use which of the following technique(s) to achieve purification?
A. Amplify the histidine-encoding sequence by PCR and add it to the gene of interest. B. Add a 6xHis-tag to the C-terminus of the protein. C. Add a series of histidine residues to the N-terminus of the protein. D. All of the choices are correct.
In humans, ability to roll the tongue (R) is dominant to being unable to roll (r). Having freckles (F) is dominant to having no freckles (f)
If a woman heterozygous for both traits married a man with no freckles who couldn't roll his tongue, what is the probability that they would have a freckled, tongue-rolling child? A. 9/16 B. 3/16 C. 1/16 D. 3/4 E. 1/4
Which of the following methods is the quickest and most common way to diagnose yeast vaginitis?
A) culture B) India ink preparation C) potassium hydroxide (KOH) preparation D) saline wet mount