Should a genetic abnormality arise, ________ prevent a cell from progressing uncontrollably through the cell cycle.
A. cis-acting elements
B. checkpoint proteins
C. trans-acting elements
D. growth factors
E. Ras's
B. checkpoint proteins
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According to research done by Baron, Caughey, and Prado, how do prions move within the brain?
a. They use receptors on the surfaces of nerve cells. b. They use vesicles found inside the nerve cells. c. They use tunneling nanotubes. d. They pinch off the nerve cell membrane. e. They stick to the outer surfaces of nerve cells.
Sam was in a terrible head-on collision. When he recovered from all of the obvious, external injuries, the once affable and happy-go-lucky person had become surly and very unfriendly. Which part of his cerebrum was most likely damaged?
A) prefrontal cortex B) Broca's area C) thalamus D) postcentral gyrus
Typically, nitrogen atoms are composed of electrons, protons, and neutrons. An isotope of nitrogen could
A) be positively charged. B) be negatively charged. C) have more protons than the usual nitrogen atom. D) have more neutrons than the usual nitrogen atom.
A clinical sample labeled as "sputum" was collected from
A. the skin. B. the blood. C. the central nervous system. D. a piece of tissue. E. the lungs.