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86 Cards in this Set

  • Front
  • Back
Major classes of lipoproteins?
chylomicrons, very low density lipoprotein, intermediate density lipoprotein, low density, high density
what are chylomicrons produced from and where?
intestinal cells, from dietary lipids
where is VLDL produced, of what?
liver, dietary carbohydrate
where are VLDL and chylomicrons hydrolyzed? by what? to what?
blood.
lipoprotein lipase to fatty acids and glycerol
what are fatty acids converted to in adipose tissue?
converted to triaceylglycerol and stored
IDL consists of what?
remaining VLDL after digestion of some of the TGs
Fate of IDL? where?
endocytosed by liver cells and digested by lysosomal enzymes or converted to LDL by further digestion of TGs.
Occurs in liver and peripheral tissues
How does cholesterol travel?
as a component of blood lipoprotein. synthesized by many tissues.
Key cholesterol regulatory enzyme?
HMG CoA reductase
Fate of cholesterol in liver? endocrine glands?
bile salts, steroids
Purpose of HDL?
transfer proteins to chylomicrons and VLDL. Picks up cholesterol from tissue and returns it to liver. (good cholesterol)
Fate of fatty acids in fasting? in the liver?
oxidized to energy.
Ketone bodies in the liver
which are then oxidized by tissues and kidney.
Eicsanoids are derived from what?
polyunsaturated fatty acids.
How are polyunsaturated fatty acids classified?
according to position of first double bond from omega end (3 or 6)
phosphoglycerides contain what?
fatty acid esterified to position 1 and 2 and a phosphoryl at group 3
Phoshoglycerides are the major component of what?
lipid bilayer (hence phospholipid bilayer)
cholesterol is in there too!
Digestion of lipid requires what 2 enzymes?
bile salts and pancreatic secretions (lipase)
lipase breaks TGs into what?
2-monoacylglycerols and free fatty acids, packages them into micelles
bile salts do what?
emulsify, break down into tiny droplets
Fatty acids in micelles are activated by what enzyme? FORM WHAT?
thiokinase (fatty acyl CoA synthase)
Form fatty acyl CoA
fatty acyl CoA reacts with______ to form a ________
diacylglycerol

triacylglycerol
Once absorbed in the gut,TGs travel to ________ system packaged as _________and eventually enter the _______________(circulation)
lymphatics
chylomicrons
blood
de novo synthesis of fatty acids from acetyl CoA occurs where?
cytosol
Acetyl CoA is derived mostly from what?
glucose
Acetyl CoA is converted by acetyl CoA carboxylase to __________
reversible?
acetyl CoA carboxylase
malonyl CoA
irreversible

malonyl-CoA is produced and inhibit the transfer of the fatty acyl group from acyl CoA to carnitine with carnitine acyltransferase, which inhibits the beta-oxidation of the fatty acid in mitochondria.
how many carbons are added at a time to the growing fatty acyl chain? where do the carbons come from?
2
3 carbon malonyl CoA
What energy source is needed form fatty acid synthesis?
NADPH
where is NADPH produced?
pentose phosphate pathway
palmitate is produced from what reaction? converted to what?
fatty acid synthesis complex
fatty acyl CoAs by elongation and desaturation
fatty acyl CoA combines with WHAT, WHERE to form triacylglycerols?
glycerol-3 Phosphate
liver
How are TGs packaged? where are they secreted?
VLDL
blood
glucose enters the liver cell and is converted to what via glycolysis?
pyruvate, which enters the mitochondria
pyruvate is converted to ________ by pyruvate dehydrogenase?
acetyl CoA
pyrvuate is converted to _________ by pyrvuate carboxylase?
oxaloacetate
Because Acetyl CoA cannot cross the mitochondrial membrane to enter the cytosol for fatty acid synthesis
acetyl CoA and oxaloacetate condense to form Citrate, which can cross the membrane
citrate is cleaved to what in the cytosol? by what enzyme? What does the enzyme require?
oxaloacetate and acetyl CoA
CITRATE LYASE
ATP and insulin
oxaloacetate is reduced in the cytosol to what?
what energy source used?
malate
NADH
in the cytosol, malate is converted to_______ and NADPH is produced, CO2 released
What is the enzyme that catalyzes this reaction?
pyruvate
malic enzyme
pyruvate Can reenter the mitochondria and is reutilized
NADPH supplies reducing equivs for reactions in fatty acid synthase complex
After citrate leaves the mitochondria, it is converted to _______, which goes on to be used for fatty acid synthesis
acetyl CoA
Fatty Acid Synthesis complex is located where?
in the cytosol
NADPH is produced by which two pathways?
malic enzyme
pentose phosphate pathway
acetyl CoA reacts with what residue and transfers what?
phosphopantetheinyl residue
acetyl group
malonyl CoA forms a thioester with what group?
phosphopantetheinyl sulfhydryl group
Malonyl CoA forms from what?
What kind of reaction?
Requires what coenzymes?
acetyl CoA
carboxylation
ATP and biotin
what enzyme catalyzes the formation of malonyl CoA from acetyl COA?
acetyl CoA carboxylase
activated by dephosphorylation, citrate, and insulin
Elongation of the growing strand until how many carbons are formed? name this molecule
16
palmitate
fate of palmitate?
can be desaturated to a series of fatty acids
In intestinal cells TGs are packaged as what?
chylomicrons
Liver uses glycerol to make what?
glycerol 3-P by a reaction that requires ATP and is catalyzed by glycerol kinase
adipose tissue cannot generate glycerol-3P from glycerol because it lacks_______
glycerol kinase
liver and adipose can convert glucose through glycolysis to DHAP which reduces to _______
glycerol 3-P
What state does TG production occur in?
Fed state
what enzymes are active in the fed state?
glucokinase, phosphofructokinase 1, pyruvate kinase
pyruvate deydrogenase is dephosphorylated and active
pyruvate carboxylase is activated by acetyl CoA
citrate lysase is induced
acetyl CoA carboxylase is induced, activated by citrate
fatty acid synthesis complex is induced
Malonyl CoA is the product of what?
acetyl CoA carboxylase
malonyl CoA inhibits carnitine acyltransferase I and prevents _______from entering the mitochondira to undergo B-oxidation
synthesized fatty acids
Synthesis of TGS in adipose tissue must make its own glycerol because it lacks?
glycerol kinase
glucose is converted to DHAP to later form __________which is used to produce glycerol
glycerol-3P
The two major carriers of TGs in the blood are...
VLDL
chylomicrons
broken down TGs have two fates:
1. oxidized for energy
2. converted to TGs and stored
glycerol is converted to ________ and oxidized for energy in the liver
DHAP: dihydroacetone phosphate (a member of the glycoytic pathway)
Glycerol (Glycerol kinase) Glycerol-3-phosphate (Glycerol-3-phosphate dehydrogenase) Dihydroxyacetone phosphate (DHAP)
(Triosephosphate isomerase) Glyceraldehyde 3-phosphate
lipoproteins are made up of:
triacylglycerols
cholesterol
cholesterol esters
phospholipids
proteins
chylomicrons are the most/least dense?
least, they have the most TGs
IDL is derived from what?
VLDL
LDL has what ratio of protein/TGs
highest content of cholesterol
less TGs and more protein
what activated lipoprotein lipase? what increases it?
apo c11
insulin
how are chylomicrons taken up?
by endocytosis of liver cells, contents are degraded by lysosomal enzymes and products are released into the cytosol
Where is VLDL synthesized?
liver, after high-carb meals
VLDL is digested where? by what? into what?
peripheral tissues (adipose, muscle) by lipoprotein lipase, into IDL
IDL returns to the liver and is degraded by what?
lysosomal enzymes
HDL is synthesized by the ______and released into the blood
liver
In the fasting state, what is the fate of TGs?
lipolysis
glucagon levels stimulate lipolysis through what pathway?
cAMP rises, protein kinase A is activated
protein kinase A phosphorylates and activates Hormone sensitive lipase HSL
fatty acid is carried by what in the blood?
albumin
fatty acids are converted to _____in the liver
ketone bodies
long chain fatty acids are activated by:
forming what?
ATP
coenzyme A
forming fatty acyl CoA
What does fatty acyl CoA react with in the outer mitochondrial membrane?
carnitine, forming fatty acyl carnitine
enzyme: fatty acyl transferase I (CATI)aka CPTI
fatty acyl Carnitine passes to the inner membrane where it reforms to ___________
fatty acyl CoA, which then enters the matrix
CATI is inhibited by? why?
malonyl CoA
it is an intermediate in fatty acid SYNTHESIS! prevents a futile cycle
fatty acyl CoA undergoes______once inside the mitochondrion
beta-oxid
Beta Oxidation:
what is the first step?
1. FAD accept hydrogens from fatty acyl CoA, enol CoA is formed. enzyme: acetyl CoA dehydrogenase
Step 2,3,4 beta ox?
H20 added across double bond....just go look it up
16 carbon palmitoyl CoA undergoes how many repetitions?
seven, in the last one two acetyl CoA are formed
energy formed from one palmitoyl CoA?
7 FADH2=2ATP each
7 NADH=3ATP each
8 acetyl CoA=12 ATp each
total: 131-2ATP=129
Odd chain fatty acids produce...
acetyl CoA and propionyl CoA
propionyl CoA can be converted to...
glucose!