Biochemistry III - Lipids, Beta Oxidation, Fatty Acids

skipferl's version from 2011-10-09 00:16


Question Answer
what is amphipathichas both hyrophillic and hydrophobic properties
define a fatty acid structurelong hydrocarbon tail connected to carboxyl head
define triacylglycerol3 fatty acids and 1 glycerol
defin phosphoglyceride makeupglycerol and 2 fatty acids
describe steroid structurecontaining rings
what is the major fuel store for the bodytriacylglycerols
2 essential lipids to take in dietlinoleic and linolenic acid
what are fat dropletsthe presence of fat in chyme
what do the Apo molecules dothey signal traffic of lipoproteins
what size chains are broken down in the stomachshorter than 12 carbons
what is emulsificationit is the breakdown of large fat droplets to smaller ones, which exposes more surface area
2 mechanisms responsible for emulsificationbile salts and peristalsis
enzyme that breaks down TAGspancreatic lipase
summary of TAG digestionTAGs are degraded by pancreatic lipase to 2-monoacylglycerol and some other fatty acids
what happens to the esterfied cholesterol in the diet (15%)the Fatty acids are hydrolyzed off by cholesterol esterase creating Fatty acids and cholesterol
mechanism of pancreatic lipase breakdown of TAGsit removes fatty acids from 1 and 3 carbon, RELEASING fatty acids, and 2-monoglycerol
role of cholecystokinin (3)causes gallbladder to contract, releasing bile salts... causes exocrine cells to release enzymes... decreases gastric motility
role of secretinreleased by intestinal cells, causes release of bicarbonate neutralizing intestinal contents
makeup and role of micellesbile salts join up with free fatty acids and cholestrol and 2monoacylglycerol leaving the hydrophobic regions inside and hydrophilic outside… move lipids to enterocytes where the cells dissociate the lipids and they enter the cells
fate of bile salts from release from gall bladderreleased after stim by CCK, meet lipids, form micelles, released at enterocytes, recycled after they are also resorbed
describe long term regulation of AcCoA Carboxylaseincreased synthesis as a result of high caloric intake
what happens after the lipids are absorbed by enterocytesTAGs are resynthesized
what lipids are absorbed by enterocytesfree fatty acids, free cholesterol, 2-monoacylglycrol
function of colipaseanchors pancreatic lipase to the interface
how is cholesterol changed in intestinesmall percentage is esterfied (has group, most dont), cholesterol ester hydrolase removes this and makes it an OH group. fatty acid is released
ingerdients in the re-synthesis of TAGs in the enterocytes2-monoacylglycerol and Fatty acids >12 C’s
fate of fatty acids shorter than 10-12 Cthey are released into the blood bound to albumin
ingerdients in chylomicrons upon immediate release from enterocytes... including apoApoB48, phospholipids, eserified cholesterol, TAGs
venous tract of chylomicronssent to liver via thoracic duct and into the left subclavian vein
track of chylomicronssynthesized in enterocytes, released where they pick up ApoC and ApoE from HDL, travel thru capillaries, lose some fatty acids via lipoprotein lipase, ApoC gets returned to HDL, chylomicron remnant travels to liver
action of lipoprotein lipaseremoves fatty acids from TAGs in chylomicrons (in capillaries)
which Apo enzymes are on chylomicrons in the capillariesApoB48, ApoC (from HDL), and ApoE (from HDL)
which Apo enzymes are on chylomicron remnantsApoB48, and ApoE
what stimulates lipoprotein lipaseinsulin, and ApoC-II
function of ApoC IIstimulates lipoprotein lipase
fiunction of ApoEactivates the chylomicron receptors in liver
track of VLDLs excess TAGs are packaged into VLDLs with ApoB100, leaves liver, gets ApoC and ApoE from HDL, drops off free fatty acids with lipoprotein lipase becoming IDLs, loses ApoC and E to HDL, also gives TAGs and Phospholipids to HDL, receives Cholesterol, becomes LDL…
contents of LDLhigh cholesterol and cholesterol esters... very little TAG
where does VLDL get some extra cholesterol estersfrom HDL
what is the primary function of LDLto deliver cholesterol to tissues
how does lipoprotein lipase bind to vessel wallsit is bound VIA proteoglycans
difference between TAGs in chylomicrons and VLDLVLDL is endogenously created TAGs and chylomicrons is from dietary intake
2 main functions of HDLmobile store of Apo A, C, E.... picks up cholesterol from membranse using apoA
function of ApoAsignals aquisition of cholesterol by HDL via PCAT and LCAT enzymes
function of PCAT and LCAT enzymesallow transfer of cholesterol from membranes to HDL
where PCAT and LCAT are synthesizedliver

Fatty Acids

Question Answer
Structure of fatty acidslakyl chain with a carboxyl head group
saturated v unsaturated fatty acidssaturated have no double bonds, saturated with H’s
result of a double bond in a fatty acidkinking of the tail
result of double bonds on M.P.lower the M.P., they help maintain fluidity
2 major tissues that oxidize fatty acidsliver and muscle
form in which fatty acids are stored as energyTAGs
why are humans not able to synthesize essential fatty acidscant put double bonds near the end of the chains
which acids are essentiallinoleic and linolenic acids
where are the double bonds in linoleic acid9 and 12
where are the double bonds in linolenic acid9,12,15
what are the omega names of linoleic/linolenic acidomega 6 and omega 3
how are the greek names formed in fatty acidsthe omegas come from the position of the 1st double bond away from the omega carbon (on the end)
what starts fatty acid synthesis (triggers)glycogen stores full in the liver, glucose then tranfered into AcCoA, which gets used for fatty acid synthesis
what a high carbohydrate diets stimulateslipogenesis and glycolysis
what is Ch-REBPlipid regulator of liver… active when dephosphorylated, but not regulated by insulin, activated by glucose
location of fatty acid synthesiscytoplasm of the liver cells, CNS, mammary
rate limiting step in lipogenesissynthesis of malonyl CoA
describe overall formation process of Malonyl CoAaddition of carbon to AcCoA, via AcetylCoA carboxylse... uses bicarbonate and ATP
where does the NADPH used in fatty acid synthesis come fromit comes from the PPP and the conversion of oxaloacetate to pyruvate
source of new carbons in elongation FA reactionsmalonyl CoA
where does elongation of FA occurthe ER membrane
where does FA desaturation (add Double bond) occurin the ER membranes
enzyme responsible for desaturation of FAacyl-CoA desaturases
why cant we desaturate beyone 9th carbonacyl-coa desaturases can only work on 4,5,6, and 9
important end product of linoleic acidarachadonic acid
function of α hydroxy fatty acidsform myelin in some cells
patterns of fatty acids on TAGsusually not the same type
most active cells in converting fatty acids to TAGsliver and adipose
list the steps in fatty acid synthesis (7)transfer original add’n, add 2 carbons (mannCoA), remove CO2 and move oldest carbons, reduce end carbons using NADPH, Dehydrate, reduce distal double bond using NADPH, translocate to cys. (up)
signifigance of palmitateit can be used as a precursor to many other fatty acids
Describe the steps in glycerol phosphate formationglycolysis makes DHAP, DHAP reduced to get glycerol phosphate, Glycerol phosphate is end product
what is the starting product for TAG synthesisglycerol phosphate
describe the general steps in TAG synthesisstart with glycerol phosphate, add acyl CoA, add another AcylCoA (get phosphatidic acid), phosphate removed by adding water, 3rd acyl CoA added
similarities between TAG synth and glycerophospholipid synthesisboth use phosphatidic acid as a precursor (TAG synth after two acyl groups have been added)
signifigance of glycerol phosphatestarting product for TAG synthesis
when can adipocytes take up glucoseONLY when insulin is present
how many ACYL-CoA molecules are used in the synthesis of TAGs3
what form must fatty acids be in to be used in TAG synthesisactivated form (bound to CoA)
how do fatty acids become activated for TAG synthesisthey are bound to CoA
where is NADPH used in synthesis of TAGswhen DHAP is reduced to Glycerol phosphate
where does glycerol phosphate come from in synthesis of TAGs (liver)glucose (via DHAP) and glycerol
where does glycerol phosphate come from in synthesis of TAGs (adipose)glucose only

Beta Oxidation

Question Answer
where does beta oxidation occurin the mitochondria
what can DHAP be used fro besides TAG synthesisglycolysis or gluconeogenesis
what happens to glycerol that comes to the liver from adipocytesconverted to DHAP
what are the two steps in beta oxidation (pre and actual)release of fatty acids from TAGs and breakdown
Function of HSL/what is ithormone sensitive lipase, removes fatty acid from carbon 1 or carbon 3
2 hormones that signal fatty acid release from TAGsglucagon and epinephrine
mechanism of hormonal activation of FA release from TAGsepi or glucagon bind cAMP-creating surface receptors, cAMP stims cAMP dependent protein kinase, which phosphorylates and activates HSL (hormone sensitive lipase)
can glycerol released in FA release be used by adipocytesno
why cant glycerol be used by adipocytesthey lack glycerol kinase, plus that would defeat the purpose of adipose as a store
what happens to glycerol released by the adipocytesit goes to the liver where it is phosphorylated by glycerol kinase, then can be used in new TAGs or creation of DHAP.
how can glycerol released from adipocytes be used in glycolysis or goes to liver, gets converted to DHAP, then that DHAP is used in the 2 processes
what happens to the fatty acids removed by beta oxidation in adipocytesthey exit thru the membrane and are bound by albumin
2 tissues that cannot use fatty acids for energybrain and blood (no mito in erythrocytes)
charge on TAGsneutral
summarize the result of the steps of beta oxidation2 C’s removed from the carboxyl end of the FAs at a time
what must happen before beta oxidation can beginfatty acids must be oxidized by addition of CoA
function of acyl CoA synthetaseactivates fatty acids via CoA addition
function of carnitine palmitoyl transferase Itransfers >12 C chains from CoA to carnitine so they can be moved into the inner mitochondrial membrane
main regulation of beta oxidationavailability of activated fatty acids
function of carnitin acylcarnitine translocaseto move the canitine out of the inner Mito matrix and to cotransport the acylcarnitine into the inner mitochindiral matrix
function of carnitine palmitoyl transferase IItransfers acyl group back out of the acylcarnitine to CoA, making AcylCoA and Carnitine
summary of how fatty acids are activated and moved into the inner mito matrixthey are added to CoA with the use of ATP, then they are sent thru carnitine palmitoyl transferase which moves the Acyl group from AcylCoA to Acylcarnitine, then the acylcarnitine moves into the inner mito matrix via the carnitine acylcarnitine translocase, after this the acylcarnitine encounters carnitine palmitoyl tranferase II which moves acyl group back to acylCoA leaving carnitine to be moved back outward
what is the starting product of beta oxidation and where must it beAcylCoA, and it has to be inside the inner membrane of the mitochondria
what is an inhibitor of carnitine palmitoyl tranferase ImalonylCoA (intermediate of FA synthesis), so newly made fatty acids aren’t immediately degraded
what food product is carnitine found inmeat you idiot
what can carnitine be synthesized fromAmino Acids
four reactions that make up beta oxidationdehydrogenase, hydratase, dehydrogensase, transferase
enzyme in final step of beta oxidationthiolase
end products of beta oxidationfatty acylCoA, and acteyl CoA
most common deficiencies in beta oxidationdeficiencies in hyrolases, mainly MCAD, results in vomiting, lethargy, and coma during fasting
final product in odd chain fatty acids, what happens to itpropionylCoA, eventually converted to succinylCoA
what is proprionyl CoAthe end product of beta oxidation of odd chain fatty acids
when is alpha oxidation of FA usedwhen there are branches at every odd carbon
what type of fatty acids cannot be beta oxidizedthe frequently branched fatty acids
what is phytanic acidacid formed from the breakdown of chlorophyll

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