Term
| What type of variation in phospholipid do mitochondrial membranes contain? |
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Definition
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Term
| What do you call esters of long chain fatty acids (14 to 36 carbons), and long chain alcohols (14-36 carbons)? |
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Definition
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Term
| Where are waxes found in the eye? |
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Definition
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Term
| What do you call lipids derived from eisacanoic acids such as arachidonic acid? |
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Definition
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Term
| What type of lipids have a sphingosine backbone rather than a glycerol backbone? |
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Definition
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Term
| What is a common name for the glycolipid N-acetylmuramic acid? |
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Definition
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Term
| In what class of lipids is a cerebroside? |
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Definition
| glycolipid or glycosphingolipid |
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Term
| A ceramide plus a phosphochline gives what? |
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Definition
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Term
| If you replace the phosphocholine group of a sphingomyelin with a carbohydrate, what do you get? |
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Definition
| glycolipid or a glycosphingolipid such as e.g. cerebroside or ganglioside |
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Term
| What three types of lipids are found in all cell membranes? |
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Definition
1) cholesterol 2) glycolipids (remember these are derived from sphingomyelines with the phosphocholine replaced by a carbohydrate) 3) phospholipids (just your basic glyercerol backbone with a phosphate polar group and two fatty acid chains) |
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Term
| Why would one find more phosphatidylcholine facing the extracellular aqueous environment and phosphatidylethanolamine facing the intracellular aqueous environment? |
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Definition
| Phosphatidylcholine has a positively charged N with four bonds. For some unknown reason phospholipids with net positive charges tend to occur exteriorly. |
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Term
| What makes unsaturated fatty acids in the cell membrane more flexible? |
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Definition
| The fatty acids slid by one another more easily when double bonds are present. |
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Term
| Is it true that cholesterol causes membrane rigidity under the narrow temperature range above and below 37 degrees celsius? |
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Definition
Interestingly no, it is not true. At lower temperatures outside the narrow temperature range, cholesterol actually increases membrane fluidity. This is in contrast to what we normally think of cholesterol, which provides rigidity to the cell membrane at temperatures greater than 37 degrees celsius. |
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Term
| What type of proteins cross or extend into the lipid bilayer, touch both membrane lipids? |
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Definition
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Term
| What type of proteins are only associated with one side of the phospholipid bilayer? |
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Definition
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Term
| Which type of membrane proteins can be separated merely with the use of aqueous salts? |
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Definition
extrinsic proteins (makes sense because they only touch one side of the lipid bilayer) |
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Term
| How would you separate intrinsic proteins from the lipid bilayer? |
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Definition
| It takes a strong detergent like methyl octylglycoside since intrinsic proteins are touching both sides of the phospholipid bilayer. |
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Term
Is rhodopsin a type of intrinsic or extrinsic protein? |
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Definition
| Rhodopsin is an intrinsic protein which one might expect since intrinsic proteins are involved in transduction of light |
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Term
| What type of proteins are the glycocalyx components? |
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Definition
| The glycocalyx components are extrinsic cell membrane proteins which one would expect since extrinsic cell membrane proteins have more passive roles such as structural roles, but extrinsic proteins like instrinsic proteins are involved in transduction signalling. Extrinsic proteins are also involved in cell movement. e.g. myosin and actin components |
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Term
| What do you call the outer sugar covering of a cell? |
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Definition
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Term
| Which type of carbohydrate components can also be found on the membranes of intracellular organelles? |
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Definition
| glycolipids and glycoproteins, while carbohydrates are usually found on the extracellular surface of cell membranes |
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Term
| Will deprivation of cervonic acid lead to reduced viscosity of photoreceptor membrane discs? |
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Definition
| While higher concentration of cervonic acid (a polyunsaturated essential fatty acid)in the photoreceptor membranes is responsible for the increased viscosity of the photoreceptors, there seems to be a preservation mechanism of this by the body since deprivation of cervonic acid in animals showed no impaired fluidity of the photoreceptors discs. |
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Term
| How does vitamin E work in the eye? |
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Definition
| Binds free radicals in peroxides that would otherwise attack the double bonds in fatty acids and convert them into fragmented aldehydes. |
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Term
| What is the cause of the cherry red spot on the Macula seen in Tay-Sach's disease? |
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Definition
| the accumulation of a partially degraded ganglioside GM2 due to the lack of the enzyme hexosaminodase A which would normally break down the N-acetyl galactosamine. |
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Term
What is the function of vitamin A in the eye? |
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Definition
1) visual transduction 2) aids proper development in corneal epithelial and conjunctival tissues |
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