Term
| What two types of transport can there be? |
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Definition
Passive transport occurs down concentration gradients; no energy is required.
Active transport occurs up concentration gradients; energy is required. |
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Term
| What is the differnce between diffusion and osmosis? |
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Definition
Diffusion is when you transport a solute down its concentration gradient.
Osmosis is when you transport water (a solvent) down its concentration gradient. |
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Term
True or False?
At equilibrium, molecules stop moving across a membrane, because the two concentrations are equal. |
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Definition
| False, the molecules keep moving back and forth but the contration on either side remains constant. |
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Term
| When does osmosis happen? What is the difference between hypertonic, isotonic and hypotonic solutions? |
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Definition
Osmosis occurs if a solute is not able to pass through the semi-permeable membrane. In that case, water will move to the side of higher concentrated solute to make the concentrations on each side equal.
Relative to other solute concentrations,
- a solution is hypertonic if it has a higher concentration of solute
- a solution is isotonic if it has an equation concentration of solute
- a solution is hypotonic if it has a lower concentration of solute
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Term
What are plant and animal cells called when,
- they have a hypotonic solution (a lot of water)?
- they have an isotonic solution (a medium amount of water)?
- they have a hypertonic solution (not a lot of water)?
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Definition
Hypotonic:
animal cell = lysed
plant cell = turgid (normal)
Isotomic:
animal cell = normal
plant cell = flacid
Hypertonic:
animal cell = shriveled
plant cell = plasmolyzed |
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Term
What is facilitated diffusion?
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Definition
| It is a medium between diffusion (substrate down a concentration gradient) and active transport. A substrate is guided down a gradient through a substrate-specific enzyme. |
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Term
| How does a sodium potassium pump work? What is another name for it? |
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Definition
This enzyme uptakes three sodium ions in the cell, is phosphorylated from ATP and changes conformation. It then loses the phosphate group, releases the sodium ions outside of the cell, uptakes two potassium ions, reverts back to its original form and releases the potassium ions in the cell.
Because it is phosphorylated by ATP by hydrolysis of the ATP, it is also called sodium potassium ATPase. |
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Term
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Definition
An enzyme transports H+ out of the cell, up the concentration gradient, with the help of ATP.
As these H+ move back into the cell, down the concentration gradient, through a different enzyme, it gives energy for other molecules to enter the cell. |
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Term
| What three ways are large molecules transported through the plasma membrane? |
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Definition
In phagocytosis and penocytosis, particles and liquid droplets, respectively, are engulfed into the membrane through vacuoules, and internalized.
In receptor-mediated endocytosis (the major method), substrates bind to receptors on the outside of the cell and then the vacuole forms from the plasma membrane and the substrate is internalized. The vacuole in this example is a coated pit. |
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