Lipid Met and Transport Flashcards
Give an overview of how phospholipids can be made from triacylglycerols or diacylglycerols
Show how phosphatidic acid is a key intermediate in phospholipid metabolism, and how it links to metabolism of mono-, di-, and triacylglycerols.
-glycerol -> G3P which can be changed into phosphatidic acid
-PA is int for both pathways
-PA can then go into phospholipid biosynth or triglyceride biosynth
-metabolism of triaglycerols are linked with phospholipid met enzyatically
-enzyme lipin regulates both pathways
What are the cellular locations of phospholipid synthesis and degradation?
-synthesis: euks = endoplasmic reticulum, proks = plasma mem
-remodelling: plasma mem
-degradation (lipoylsis): cytosol and lipid storage droplets
Briefly distinguish between the synthesis of phospholipids and sphingolipids
-Sphingolipid synth: palmitoyl-CoA + Serine -> ceramide; can also exchange head groups to make other sphingolipids
-Phospholipids: glycerol -> phosphatidate -> phospholipids like cardiolipin and phosphatidylinositol
how are the overall structures of phospholipids and sphingolipids similar, and how are they different?
-similar: both polar, both include FA
-different: one has glycerol (c=o), one has Sphingosine (OH)
what are the building blocks for the synthesis of phospholipids and sphingolipids?
-most phospholipids have a glycerol backbone, FA chains and a polar head (phosphate group)
-sphingolipids have no glycerol but have sphingosine and 1 FA
Provide an overview of how dietary triacylglycerols emulsified, hydrolyzed, reconverted, and formed into chylomicrons. What are the major components of chylomicrons and other lipoproteins?
Very briefly describe the major categories of lipoproteins (HDL, IDL, LDL, VLDL, chylomicrons), and summarize their physiological roles
-ULDL: chylomicra; from ingested food; loses TAG to muscle and adipose
-VLDL: from liver; converted into IDL/LDL
-IDL: from blood; get converted into LDL
-LDL: from blood; binds to tissue with LDLr; oxidizes and forms plaques
-HDL: from liver; scavenges for cholesterol and returns to liver
(high, int, low, very low - density lipoprotein)
How do free fatty acids or fatty acids in lipoproteins enter cells? How does cholesterol in HDL enter cells?
-free fatty acids bind to carrier proteins
-fatty acids can also diffuse into cell
-receptor-mediated endocytosis
-lipoprotein complexes enter cell via receptor-mediated endocytosis
-cell internalizes cholesterol via RME when HDL binds to its receptor on the cell
What tissues are the principal location of de novo tricacylglycerol synthesis?
-liver tissue
(de novo = from new)
Very briefly summarize the regulation of fatty acid mobilization from adipocytes
-lipases regulate
-Acute: regulated through cAMP and insulin and AMPK
-chronic: regulated by gene expression and diet
what major hormones trigger lipolysis?
glucagon and epinephrine
what is the role of perilipins in TAG storage?
-they are key proteins in regulating lipid met
-embed in droplets in adipocytes
-help with formation and maturation of fat droplets
-help with regulation of lipolysis
-catalysis and regulation
how do lipases play a role in mobilization of fatty acids?
-three main lipases that each take a step in the breakdown and mobilization
-removes FA from the molecule, one at a time
-cleaves ester from free glycerol
Give an overview of how membrane lipids other than phospholipids (cholesterol; sphingolipids) play a structural role in lipid rafts
-there may be lipid anchors for interactions
-glycolipid receptors deal with cascades
