A strain of penicillin-resistant N. gonorrhoeae that does not have a plasmid is isolated. A lysate made from the bacterium cannot degrade penicillin in an in vitro assay. When a culture of this strain is grown in a solution that contains radioactive penicillin, the amount of penicillin found within cells is less than the amount found within cells from a nonresistant strain. The DNA sequence of the porin gene from the resistant strain does not have any mutations. What is the most likely mechanism of resistance in this strain?
A) A mutation in the mtr gene has occurred, resulting in fewer efflux pumps.
B) A penA nonsense mutation has occurred.
C) A penA missense mutation has occurred.
D) The bacterial genome carries the penr gene.
A) A mutation in the mtr gene has occurred, resulting in fewer efflux pumps.
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Antidiuretic hormone (ADH) functions at the cellular level by _____
A) stimulating the reabsorption of glucose through channel proteins B) triggering the synthesis of an enzyme that makes the phospholipid bilayer more permeable to water C) causing membranes to include more phospholipids that have unsaturated fatty acids D) causing an increase in the number of aquaporin molecules of collecting duct cells E) decreasing the speed at which filtrate flows through the nephron, leading to increased reabsorption of water
What is the function of a statolith?
A. to determine whether an organism is stationary or moving B. to determine the direction of gravity C. to amplify sound waves D. to detect vibrations in water
Ribosomal subunits
a. come together in threes to form functional units. b. are composed of mRNA and structural proteins. c. are synthesized in the cytoplasm. d. converge only when mRNA is to be translated. e. are transcribed from the complementary strand of DNA that is used for tRNA transcription.
In deuterostomes the first opening develops into the:a
coelom. b. gut. c. anus. d. mouth. e. nostril.