Phospholipids Flashcards
what are the 2 structure classes of phospholipids?
- fatty acid structure
- isoprene structure
what is a phospholpid made of?
Phospholipids contain glycerol, two fatty acids, a phosphate and a basic component
Phospholipids consist of a glycerol molecule, two fatty acids, and a phosphate group that is modified by an alcohol. The phosphate group is the negatively-charged polar head, which is hydrophilic. The fatty acid chains are the uncharged, nonpolar tails, which are hydrophobic.
what are the 3 components of a fatty acid?
-# of derivatives, i.e. phospholipids –> 3 components
- 3 hydrocarbon chain
- phosphate-alcohol head group
- backbone
–> glycerol (phosphoglyceride)
–> ceramide (sphingomyelin)
what are the different backbones of a fatty acid to make a phosphoglyceride vs. sphingomyelin? what are the other 2 components that are the same?
different backbone
–> glycerol (phosphoglyceride)
–> ceramide (sphingomyelin)
same:
3 hydrocarbon chain
phosphate alcohol head group
phosphoglycerides
-phospholipid with glycerol backbone
–> if both fatty acids are linked to glycerol backbone with an ester link= phosphatidate
–> if one fatty acid is linked to glycerol backbone with ester link, while the other has an ether link = plasmalogen
phosphatidates
basic structure of phospholipid = phosphatidic acid
phosphatidates vs plasmalogens- what is the differences in linkages of the fatty acid to the glycerol backbone?
–> if both fatty acids are linked to glycerol backbone with an ester link= phosphatidate
–> if one fatty acid is linked to glycerol backbone with ester link, while the other has an ether link = plasmalogen
3 most common phosphoglycerides in cell membrane
- phosphatidylethanolamine
- phosphatidylserine
- phosphatidylcholine
sphingomyelin/ sphingolipid
common phospholipid with ceramide backbone
phospholipid synthesis (glycerophospholipids) - 4 steps and location
-luminal surface of smooth ER and inner mitochondrial membrane
- synthesis of glycerol backbone
- attachment of fatty acids to backbone via ester linkage
- addition of head group
- exchange/ modify head group
*steps 1 & 2 are also for Triacyl glycerol synthesis
step 1 and 2 of phospholipid synthesis
- synthesis of glycerol backbone
- attachment of fatty acids to backbone via ester linkage
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–> creates phosphatidic acid
step 3 of phospholipid synthesis
- addition of head group
which nucleotide base is used to do this?
use cytosine
one of the hydroxyl is first activated by attachment of a nucleotide, cytosine diphosphate (CDP)
CMP is displaced via nucleophilic attack and replaced by a head group (i.e. serine)
another possibility utilized by eukaryotes is the addition of CDP head group to diacylglycerol
step 4 of phospholipid synthesis
- exchange/ modify head group
-phosphatidylserine and phosphatidylethanolamine can be interconverted in a reversible head group exchange rxn
phosphatidylethanolamine can be converted to phosphatidylcholine by addition of 3 methyl groups
–> methyl groups are donated by S-adenosylmethionine (SAM) a common methyl donor (adoMet)
what is the starting molecule for phospholipid synthesis and where is it found? what is created when the fatty acids are added to the backbone in the first two steps?
glycerol-3-phosphate, derived from glycerol with added phosphate in the liver
–> which is from dihydroxyacetone phosphate DHAP (intermediate in glycolysis)
–> make phosphatidic acid
what is phosphatidylinositol’s function?
signalling- less common phospholipid
