Term
| What is measured by the differences in positive and negative charges on each side of the membrane? |
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Definition
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Term
| What is the transport of molecules from one area to another without energy called? |
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Definition
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Term
| What is it called when a cell membrane only allows certain molecules to pass from one side to the other? |
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Definition
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Term
| What is the passive transport (diffusion) of molecules across the plasma membrane with the help of transport proteins called? |
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Definition
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Term
| Some plants increase this type of fatty acids in their phospholipids to make their membranes more fluid in colder conditions. |
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Definition
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Term
| Integral membrane proteins that transport specific ions or molecules across the plasma membrane. |
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Definition
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Term
Technique scientists use to support the fluid mosaic model.
Involves freezing a cell and then breaking it apart at the membrane. |
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Definition
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Term
Solution that has a higher solute concentration than that found inside the cell.
Resulting in water flow out of the cell. |
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Definition
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Term
| Gradient of electrical energy established by a membrane's potential. |
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Definition
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Term
| The fluidity of the plasma membrane is dependent on this environmental factor. |
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Definition
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Term
| Importing of macromolecules from the cell via fusion with the plasma membrane forming vesicles. |
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Definition
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Term
| The random movement of molecules spreading out in available space. |
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Definition
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Term
| Molecules that are both hydrophobic and hydrophilic at the same time on different parts. |
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Definition
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Term
| Tran-membrane proteins that have hydrophobic regions that embed in the hydrophobic interior of the plasma membrane. |
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Definition
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Term
| Plants cells in hypotonic solutions become ________. |
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Definition
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Term
Solution that has a lower solute concentration than that found inside the cell.
Resulting in water flow into the cell. |
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Definition
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Term
Model of cell membrane structure supported by current evidence.
States that proteins freely "float" within the bilayer "ocean". |
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Definition
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Term
| Differences in the concentration of molecules between two areas of a solution is called a concentration _________. |
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Definition
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Term
| Diffusion of water across a selectively (semi) permeable membrane due to differences in the concentrations of solutions of each side of that membrane. |
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Definition
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Term
| Type of endocytosis that triggers the formation of coated pits on the plasma membrane. |
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Definition
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Term
| Plant cells in hypertonic solutions become ________. |
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Definition
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Term
| Type of transmembrane protein that passes positively charged hydrogen ions across a membrane. |
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Definition
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Term
| Proteins that attach to the surface of the plasma membrane are called __________. |
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Definition
| Periferal (sp? - peripheral) |
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Term
| Type of transport across the plasma membrane with the help of transport proteins that requires energy. |
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Definition
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Term
| Type of lipids that form each half of the cell membrane. |
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Definition
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Term
| In animal cells, the fluidity of the membrane is also dependent on this chemical factor. |
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Definition
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Term
| Side of the fracture facing the exterior environment. |
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Definition
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Term
Solution that has the same solute concentration of that found inside the cell.
Resulting in no water flow. |
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Definition
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Term
| __________ or electrically neautral molecules can easily pass through the plasma membrane. |
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Definition
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Term
| Exporting of macromolecules from the cell via fusion of vesicles with the plasma membrane. |
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Definition
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Term
| Membrane that separates the cell from its non-living surroundings. |
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Definition
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Term
| Side of the fracture facing the plasma membrane. |
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Definition
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Term
| What are cell membranes composed of? |
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Definition
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Term
| Why are cell membranes a bi-layer? |
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Definition
| The phospholipids are arranged as a bilayer (two molecules thick). The phospholipids are stacked with the non-polar hydrocarbon chains pointed inward while the polar ends act as the external surface as shown in graphic on the left. The structure of the bilayer is another application of the solubility principle of "likes dissolve likes". |
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Term
| Which parts of the bilayer are hydrophobic? |
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Definition
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Term
| Which parts of the bilayer are hydrophilic? |
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Definition
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Term
| Are cell membranes amphipathic? |
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Definition
| Yes, because the phospholipids have hydrophobic tails and hydrophilic heads. |
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Term
| What does selectively or semi-permeable mean? |
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Definition
| Cell membrane has some control over what can cross it, so that only certain molecules either enter or leave the cell. |
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Term
| Why is selectively or semi-permeable an important property of cell membranes? |
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Definition
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Term
| What is the fluid mosaic model? |
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Definition
Proteins embedded in the phospholipid bilayer of the membrane.
Membrane is a mosaic of proteins that float around in the bilayer. |
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Term
| What other evidence supports the fluid mosaic model? |
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Definition
Experimental evidence for the “fluid” property of membranes:
1. Mark proteins on cells with different fluorescent dyes.
2. Fuse the cells to form “hybrids”.
3. Observe migration and mixing of proteins |
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Term
| Name an environmental factor that can alter membrane fluidity. |
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Definition
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Term
| How can animals adjust the fluidity of the plasma membrane? |
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Definition
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Term
| How can plants adjust the fluidity of the plasma membrane? |
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Definition
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Term
| What are some of the functions of integral membrane proteins? |
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Definition
Transport
Enzymatic activity
Signal tranduction
Intercellular joining
Cell-cell recognition
Attachment to the cytoskeleton and extracellular matrix |
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Term
| Why is adjusting the fluidity of the plasma membrane important? |
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Definition
In order to work properly, membranes must remain fluid.
Cells alter lipid composition of membranes to cope with changes in fluidity due to temperature flux. |
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Term
| What are some of the functions of peripheral membrane proteins? |
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Definition
| Some peripheral proteins may serve the role of enzymes. Others are involved in changing cell shape during cell division & muscle contraction, or linking cells together. |
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Term
| What are transport proteins? |
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Definition
| Integral Membrane Proteins (IMPs) that transport specific molecules or ions across biological membranes |
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Term
| What would happen if I placed a cell in an isotonic solution? |
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Definition
| Nothing because there is no difference in the concentration gradient |
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Term
| What would happen if I placed a cell in an hypotonic solution? |
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Definition
| The cell would burst (lyse) because water would rush into the cell to dilute its higher concentration of solutes |
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Term
| What would happen if I placed a cell in an hypertonic solution? |
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Definition
| The cell would shrink because water flows out to dilute the surrounding areas of higher solute concentration |
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Term
| What is osmotic concentration? |
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Definition
| The total solute concentration of a solution |
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Term
| What is osmotic pressure? |
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Definition
| The pressure exerted by water flowing into a hypeertonic solution across a spm. |
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Term
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Definition
| The reversal of osmosis by exerting more pressure than the osmotic pressure o the hypertonic side of a spm. |
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Term
| What happens as a result of reverse osmosis? |
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Definition
| Water flow in the opposite direction of that due to osmosis |
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Term
| How is facilitated diffusion different from diffusion? |
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Definition
| Facilitated diffusion is the diffusion of solutes across a membrane with the help of transport proteins; whereas diffusion is the action of molecules of any substance spreading outin available space. |
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Term
| How does a Sodium Potassium pump work? |
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Definition
| It is an electrogenic pump that generates electrochemical gradient by pumping two K+ ions inside for every three Na+ ions that it moves out (Animals) |
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Term
| What is the function of a Sodium Potassium pump? |
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Definition
| Sodium and potassium ions are pumped in opposite directions across the membrane building up a chemical and electrical gradient for each. These gradients can be used to drive other transport processes. In nerve cells the pump is used to generate gradients of both sodium and potassium ions. These gradients are used to propagate electrical signals that travel along nerves. |
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Term
| What is an electrochemical gradient similar to that we use in our everyday lives? |
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Definition
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Term
| What is an electrogenic pump? |
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Definition
| Special tranport proteins that generate voltage gradients across a membrane |
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Term
| Give an example of an electrogenic pump in animals and in plants. |
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Definition
Animals - Sodium Potassium Pump
Plants - Proton Pump |
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Term
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Definition
| An ATP-powered pump that transports one solute can indirectly drive the active transport of several other solutes via a different protein |
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Term
| How does co-transport work? |
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Definition
| As H+ leaks back across membrane (with the gradient) through special transport proteins it carries other substances with it (sucrose; against the gradient) |
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Term
| Compare and contrast the three types of endocytosis. |
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Definition
1. Phagocytosis- Process of engulfing a particle by wrapping pseudopodia around it forming a vacuole
(Phago: Eat)
2. Pinocytosis- indiscriminant engulfing of extracellular fluid by the plasma membrane; forming small vesicles
(Pino: drink)
3. Receptor mediated endocytosis- when specific molecules bind to specialized receptors on the cell's surface it activates coat proteins to form vesicles containing the bound molecules |
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Term
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Definition
| Extensions of the cytoplasm from the plasma membrane forned by cytoplasmic streaming |
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Term
| What are pseudopodia used for? |
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Definition
| Particles in the engulfed vacuole are digested by fusing with a lysosome |
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Term
| The sodium-potassium pump is called an electrogenic pump because it |
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Definition
pumps hydrogen ions into the cell
contributes to the membrane potential.
pumps equal quantities of Na+ and K+ across the membrane
ionizes sodium and potassium
pumps hydrogen ions into the cell |
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Term
Which of the following would indicate that facilitated diffusion was taking place? |
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Definition
A substance was slowing as it moved down its concentration gradient
Substances were moving against the diffusion gradient
A substance was moving from a region of low concentraion into a region of higher concentration
ATP was being rapidly consumed as the substance moved
A substance was diffusing much faster than the physical condition indicated it should.
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Term
| All of the following cellular activities require ATP energy except |
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Definition
cytoplasmic streaming
exocytosis
movement of O2 into the cell.
protein synthesis
Na+ ions moving out of the cell |
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Term
| Mutant cells lacking coated pits would most likely be |
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Definition
unable to actively transport ions into the cell
characterized by a smooth surface on both sides of the bilayer
unable to adapt to the cold
deficient in receptor-mediated endocytosis.
involved in steroid synthesis
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Term
| The movement of a substance across a biological membrane against its concentration gradient with the help of energy input is which of the following? |
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Definition
osmosis
active transport.
diffusion
exocytosis
facilitated diffusion |
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Term
| All of the following statements about membrane structure and function are true except: |
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Definition
voltage across the membrane depends on an unequal distribution of ions across the plasma membrane
special membrane proteins can cotransport two solutes by coupling diffusion with active transport
both sides of a membrane are identical in structure and function.
diffusion of gases is faster in air than across membranes
diffusion, osmosis, and facilitated diffusion do not require any energy input from the cell |
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Term
| Of the following functions, the glycoproteins and glycolipids of animal cell membranes are most important for |
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Definition
facilitated diffusion of molecules down their concentration gradients
the ability of cells to recognize like and different cells.
active transport of molecules against their concentration gradients
maintaining membrane fluidity at low temperatures
maintaining the integrity of a fuid mosaic membrane |
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Term
| What is one of the ways that the membranes of winter wheat are able to remain fluid when it is extremely cold? |
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Definition
by increasing the percentage of unsaturated phospholipids in the membrane.
by decreasing the number of hydrophobic proteins in the membrane
by increasing the percentage of cholesterol molecules in the membrane
A, B, and C
A and B |
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Term
| The movement of potassium into or out of an animal cell requires |
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Definition
plant hormones embedded in the cell membrane
high cellular concentrations of potassium
glucose for binding and releasing ions
low cellular concentrations of sodium
an energy source such as ATP or a proton gradient. |
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Term
| All of the following processes take material into cells except |
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Definition
pinocytosis
carrier-facilitated diffusion
exocytosis.
active transport
endocytosis |
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