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BioChem Pershini
Exam 2
Question | Answer |
---|---|
What are lipids? | a substance that is soluble in the chloroform or methanol due to their hydrophobic character |
What are fatty acids? | carboxylic acids with long hydrocarbon or aliphatic side groups |
What two carbon species are the most common in biological systems? | C16 and C18 |
In double bonds, polyunsaturated fatty acids double bonds are? | not conjugated and are always cis |
16:0 | palmitic acid, hexadecanoic acid, CH3(CH2)14COOH |
18:0 | stearic acid, octadecanoic acid, CH3(CH2)16COOH |
16:1n-7 | palmitoleic acid, 9-hexadecanoic acid, CH3(CH2)5CH=CH(CH2)7COOH |
18:1n-9 | oleic acid, 9-octadecanoic acid, CH3(CH2)7CH=CH(CH2)7COOH |
18:2n-6 | linoleic acid, 9,12-octadecadienoic acid, CH3(CH2)4(CH=CHCH2)2(CH2)6COOH |
18:3n-3 | alpha linoliec acid, 9,12,15-octadecatrienoic acid, CH3CH2(CH=CHCH2)3(CH2)6COOH |
18:3n-6 | lambda linoliec acid, 6,9,12-octadecatrienoic acid CH3(CH2)4(CH=CHCH2)3(CH2)3COOH |
20:4n-6 | arachinidonic acid, 5,8,11,14-Eicosatetraenoic acid, CH3(CH2)4(CH=CHCH2)4(CH2)2COOH |
What are triglycerides? | triacylglycerols or fatty aids triesters that usually contain two or three different fatty acids |
How do fats(solids) and oils(liquids) differ? | whether or not there melting point is below room temperature |
-CH2CH2NH3+ | phosphatidylethanolamine |
-CH2CH2N(CH3)3+ | phosphatidylcholine |
-CH2CH(NH3+)COO- | phosphatidylserine |
phosphatidylinositol | a six ring structure with OH groups as follows: C1 up, C2, down, C3 up, C4 up, C5up, C6 down |
What is a glycerophospholipid? | a major constituent of biological membranes derived fronm glycerol-3-phosphate by esterification at C1 and C2 |
What is a sphingolipid? | a major membrane bilayer component based on C18 amino alcohol sphingosine. Sphingolipids have two saturated aliphatic tails; one from the fatty acid substituent and one from the sphingosine. |
What are ceramides? | an N-acetyl fatty acid derivatives that are the parent compound of all other sphingolipids? |
What are neutral glycosphingolipids? | B-O-glycosidic linkage cerebrosides and globosides |
What is a cerebroside? | contain one sugar usually glucose or galactose |
What is a globoside? | contain more than one sugar e.g. lactosyl ceraminde |
What are charged Glycosphingolipids? | gangliosides contain more than one sugar plus one or more sialic acid |
What is responsible for the kink in sphingosine? | The double bond |
What are the sugars in GM3 gangliosides? | D-Galactose and D-Glucose |
What are the sugars in GM2 gangliosides? | N-Acetyl-D-Galactosamine, D-Galactose and D-Glucose |
What are the sugars in GM1 gangliosides? | D-Galactose, N-Acetyl-D-Galactosamine, D-Galactose and D-Glucose |
Explain the bilayer formation? | a consequence of the amphiphathic natures of glycerophospholipids and sphingolipids (60-80 A thick) |
Transverse VS. Lateral Diffusion | Transverse is very rare with a t1/2 of several days, lateral diffusion is very rapid, thus the lipid bilayer is considered a two-dimensional fluid |
Why is the hydrophobic interior of a bilayer in constant motion? | due to the rotations about C-C bonds in the aliphatic tails |
Bilayer structure is temperature dependent | below transition temperatures, become solids, above that temperature , it becomes liquid crystal. temperature increases with the length and degree of saturation of the fatty acid chains |
How do these lipids rafts contribute to the gel-like state of the membrane in these regions? | Sphingolipids have two alipathic tails. this raises the transition temperature for the lipid rafts so they are in a gel-like state rather than a liquid crystal state. |