In the final stage of the oxidation of food molecules, a gradient of protons is formed across the inner mitochondrial membrane, which is normally impermeable to protons
If cells were exposed to an agent that causes the membrane to become freely permeable to protons, which of the following effects would you expect to observe?
(a) The ratio of ATP to ADP in the cytoplasm would fall.
(b) NADH would build up.
(c) Carbon dioxide production would cease.
(d) The consumption of oxygen would fall.
(a) If the inner mitochondrial membrane became permeable to protons, the electron-transport chain would continue to oxidize NADH to NAD+, transport electrons, and pump protons, so the consumption of oxygen would not fall. However, without the energy stored in a proton gradient, there is no way of driving the synthesis of ATP.
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An action potential is an abrupt and transient change in the membrane potential of an excitable cell
1.True 2.False
Probes for cloned genes use
a. complementary nucleotide sequences labeled with a tracer b. specific antibodies that kill all the cells except those that have incorporated the genes. c. specific enzymes that lyse all the cells except those that have incorporated the genes. d. certain bacteria that glow when they take up the genes. e. all of these.
Plants that do not develop persistent woody parts above the ground are called:a
monocots. b. dicots. c. herbaceous. d. deciduous. e. perennials
What situation relates to the reason why hot-air balloons are able to fly?
A) Precipitation falls on the leeward side of a mountain. B) Water droplets can freeze inside clouds. C) Very little rain falls at 30° north and south of the equator. D) The tops of hills are warmer than the valleys below.