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mem trans
| Question | Answer |
|---|---|
| What is the predominant, negatively charged ion in the extracellular fluid? | Cl− |
| Which of the following ions is the most abundant inside a typical mammalian cell? | K+ |
| Which of the following positively charged ions is the most abundant outside a typical mammalian cell? | Na+ |
| Transporters, in contrast to channels, work by | specific recognition of transport substrates. |
| Channels are are used in active transport. | False |
| Pumps are transporters that are able to harness energy provided by other components in the cells to drive the movement of solutes across membranes, against their concentration gradient. This type of transport is called | active transport. |
| Carbon dioxide and oxygen exchange occurs by simple diffusion directly across the membrane. | True |
| Select all of the following that are used as sources of energy for active transport: | light driven ATP driven coupled transport |
| glucose uniporter | random oscillation transports glucose according to gradient |
| Glucose-Na+ Symporter | uses the high concentration of Na+ in the extracellular field |
| H+-Lactose Symporter | Used to create H+ gradients used by plants, bacteria, and fungi |
| bacteriorhodopsin | Uses photons of light to pump H+ against their concentration gradient |
| When this transporter moves both ions in the same direction across the membrane, it is considered a --- if the ions move in opposite directions, the transporter is considered an --- . | symport antiport |
| A molecule moves down its concentration gradient by --- transport, but requires ---- transport to move up its concentration gradient. | passive active |
| The Na+/K+ pumps move _ Na+ out of the cell and _ K+ into the cell. | 3; 2 |
| Gap junctions are large pores that connect the cytosol to the extracellular space. | false |
| Which of the following channels would not be expected to generate a change in voltage by movement of its substrate across the membrane where it is found? | an aquaporin |
| Channels exclude molecules on the basis of , , and , but do not depend on specific recognition of the molecules moving through. | size shape charge |
| The stimulation of auditory nerves depends on the opening and closing of channels in the auditory hair cells. Which type of gating mechanism do these cells use? | mechanically-gated |
| Both excitatory and inhibitory neurons form junctions with muscles. By what mechanism do inhibitory neurotransmitters prevent the postsynaptic cell from firing an action potential? | by opening Cl− channels |
| The propagation of the action potential along the axon is bidirectional. v | false |
| Which of the following is required for the secretion of neurotransmitters in response to an action potential? | voltage-gated Ca2+ channels |
| Which of the following molecules can cross the cell membrane readily without assistance? | CO2 and O2 |
| What provides the energy for bacteriorhodopsin to pump protons? | Green light absorbed by retinal |
| Which protein allows water to rapidly cross cell membranes? | Aquaporin |
| What type of ion channel opens in response to a change in membrane voltage? | Voltage-gated channel |
| Which neurotransmitter is an example of an excitatory signal at the neuromuscular junction? | Acetylcholine (ACh) |
| What is the term for when the membrane potential becomes less negative? | Depolarization |
| What is a traveling wave of depolarization in a postsynaptic cell called? | Action potential |
| Which ion's influx causes inhibitory signals in nerve cells? | Cl- |
| What happens during hyperpolarization? | Membrane potential becomes more negative than resting |
| What is the average membrane potential of a typical cell? | -70mV |
| Which ions are typically found in higher concentrations outside the cell? | Na+ and Cl- |
| What percentage of ATP does the Na+-K+ pump use in animal cells? | 30% |
| How long does one complete cycle of the Na+-K+ pump take? | 10 milliseconds |
| Which type of transport moves molecules against their concentration gradient? | Active transport |
| How much faster do solutes move through ion channels compared to carrier proteins? | 1000 times faster |
| Which gradient do plants, bacteria, and fungi use for coupled transport instead of Na+? | H+ gradient |
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