In E. coli the heat shock response, which alters the proteins produced by the cell at different temperatures, is mediated by
A) degradation of chaperone proteins at high temperatures.
B) denaturing of DNA in the promoters in the genes of heat-sensitive proteins.
C) synthesis of alternative sigma factors at high temperatures to activate transcription of heat-shock genes.
D) increasing the promoter affinity of already existing polymerase sigma factors at high temperatures.
C) synthesis of alternative sigma factors at high temperatures to activate transcription of heat-shock genes.
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Which of the following is responsible for maintaining the membrane potential?
a. the Na+/K+ pump b. the diffusion gradient c. the Ca2+ pump d. the H+ pump
Cell division in the apical meristems at the tips of a plant that results in increases in height or length is called
A. mitotic growth. B. secondary growth. C. primary growth. D. herbaceous growth. E. vascular cambium growth.
Why is it that some people are unable to digest the lactose contained in dairy products?
A) Lactose can only be digested by people who produce the appropriate amounts of lactic acid. B) Lactose-intolerant people do not produce lactase, the enzyme needed to digest lactose. C) Some people do not produce any enzymes, including the one needed to digest lactose. D) The active site of the lactose enzyme can vary from person to person. E) Some people have an internal body temperature higher than others, which allows the lactase enzyme to function more efficiently.
New world monkeys have all of the following features except
A. they have flat spreading noses. B. they evolved in isolation in South America. C. they are all arboreal. D. they grasp objects with long prehensile tails. E. they have ischial callosities (thickened rump pads).