What is the role of the nuclear localization sequence in a nuclear protein?
(a) It is bound by cytoplasmic proteins that direct the nuclear protein to the nuclear pore.
(b) It is a hydrophobic sequence that enables the protein to enter the nuclear membranes.
(c) It aids in protein unfolding so that the protein can thread through nuclear pores.
(d) It prevents the protein from diffusing out of the nucleus through nuclear pores.
Choice (a) is correct. The nuclear localization signal typically contains positively charged amino acids, not hydrophobic ones [choice (b)]. Proteins are not unfolded as they enter the nucleus [choice (c)]. Proteins are actively transported in and out of the nucleus and do not diffuse through the nuclear pores [choice (d)].
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Researchers surgically fuse two of the three ossicles in the inner ear of a mouse, effectively leaving two functional, linked ossicles in place of three. When the mouse's hearing is tested, what outcome would be expected? The mouse would be _____
A) more sensitive to sound, but only in the low-frequency range B) more sensitive to sound, but only in the high-frequency range C) more sensitive to sound in general D) less sensitive to sound in general
If a membrane is impermeable to water, the flow in and flow out will both be zero
a. True b. False
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A) an ecosystem B) parasitism C) a food web D) a food chain
Which statement is TRUE regarding the negative feedback homeostatic mechanism, which occurs during temperature regulation?
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