Which of the following activities is NOT related to negative supercoiling?
a. relieving tension in DNA by unwinding the double helix
b. reversing the effect of positive supercoiling
c. twisting in the opposite direction as the two strands within the double helix
d. exaggerating the effect of positive supercoiling
e. resulting in more base pairs per turn of the double helix
Ans: d
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The movement of water through a membrane, from an area of high concentration to an area of low concentration, is known as
A) active transport. B) facilitated transport. C) passive transport. D) osmosis. E) photolysis.
Certain traits that allow pathogens to create infection and cause disease are termed
A) hyaluronidases. B) streptokinases. C) virulence factors. D) collagenases.
Pseudomonas species are occasional causes of
A) diarrheal disease. B) food poisoning from meat. C) food poisoning from dairy products. D) "flesh-eating" bacterial infections. E) urinary tract infections.
You are interested in cell-size regulation and discover that signaling through a GPCR called ERC1 is important in controlling cell size in embryonic rat cells
The Gprotein downstream of ERC1 activates adenylyl cyclase, which ultimately leads to the activation of PKA. You discover that cells that lack ERC1 are 15% smaller than normal cells, while cells that express a mutant, constitutively activated version of PKA are 15% larger than normal cells. Given these results, which of the following treatments to embryonic rat cells should lead to smaller cells? (a) addition of a drug that causes cyclic AMP phosphodiesterase to be hyperactive (b) addition of a drug that prevents GTP hydrolysis by G? (c) addition of a drug that activates adenylyl cyclase (d) addition of a drug that mimics the ligand ofERC1