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12 Cards in this Set
- Front
- Back
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What are the 3 major categories of membrane lipids? What do they all have in common? Why is this relevant?
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1. Phosphoglycerides
2. Sphingolipids 3. Cholesterol These all are amphipathic, allowing them to associate with the lipid bilayer. |
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What are phosphoglycerides? What are the 3 most common head groups of phosphoglycerides?
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Phosphoglycerides are a glycerol attached to 2 fatty acids, and a choline+ either serine, ethanol, or choline.
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What are sphingolipids? What's the formula? What are the 3 varieties?
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Sphingolipids are sphingosine+fatty acid+[X], where X is a variable group. Thus, you can have sphingomyelin. Glycolipids are sphingolipids.
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What is cholesterol? How much of the animal cell membrane does it encompass?
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Cholesterol is a small, amphipathic membrane lipid that constitutes about 50% of all animal cell membrane.
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How does the presence and cholesterol affect membrane fluidity at different temperatures?
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At low temperatures, cholesterol increases membrane fluidity. At high temperatures, cholesterol decreases membrane fluidity. This has the result of buffering the membrane fluidity, thus maintaining homeostasis.
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How many stacked plasma membrane make the thickness of one sheet of paper?
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10,000.
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What is a liposome? What broader phenomenon is operative here?
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A liposome is a lipid bilayer that has arranged into a sphere, it's most energetically favorable state. This is why lipid bilayers form a sphere around cells; any edges exposed to the hydrophobic environment would be energetically unfavorable.
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What 3 cellular functions do membrane lipids mediate?
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1. determines the gross structural properties of the membrane.
2. membrane lipids can interact with membrane proteins to affect function. 3. membrane lipids serve as precursors to other molecules, and can also be signal molecules. |
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How does lipid concentration differ between the inner and outer leaflet?
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The inner and outer leaflets have very different compositions.
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What is salient about the synthesis of membrane lipids? How does the cell compensate for this?
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The membrane lipids that are produced are produced inside vesicles, and can only be added to the inner leaflet of the vesicle, and thus can only be on the inner leaflet when the vesicle fuses with the plasma membrane. The cell compensates with the flippase enzyme, which flips the orientation of patches of the plasma membrane.
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What's an example of a membrane lipid that serves as a signal molecule/
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DAG (diacylglycerol), which is a product of PIP-2 cleavage.
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On what leaflet are glycolipids and glycoproteins principally found? What sort of bonds exist between the carbohydates and their associated lipids or proteins?
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These carbohydrate chains are found on the outer leaflet, and serve various extracellular function. There are COVALENT bonds between the carbohydrates and their substrates.
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