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Lipid Metabolism
lipid metabolism
23
Chemistry
Graduate
09/29/2008

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Term
Describe Palmitic acid in terms of the number of carbons and double bonds
Definition
Palimitic Acid- 16:0
Term
Describe arachidonic acid
Definition
20:4
Term
What is a cerebroside?
Definition
A cerebroside is a ceramide with one sugar attached
Term
What is a ganglioside?
Definition
A ganglioside is a ceramide with more than one sugar attached
Term
What tissue cannot use fatty acids as a fuel?
Definition
Erythrocytes
Term
What transports free fatty acids from the cytoplasm into the matrix?
Definition
The carnitine cycle
Term
What is the difference between acyl-CoA and acetyl-CoA?
Definition
acyle-CoA is a long chain free fatty acid
acetyl-CoA is a 2 carbon fatty acid
Term
What is the difference between acyl-CoA and acetyl-CoA?
Definition
acyle-CoA is a long chain free fatty acid
acetyl-CoA is a 2 carbon fatty acid
Term
What are the products of one round of Beta Oxidation of fatty acids?
Definition
one round of beta oxidation produces 1 FADH2, 1 NADH and an Acetyl CoA (2 Acetyl-CoA's if it's the last round of an even numbered acyl-CoA)
Term
What are the four repeated steps of beta oxidation?
Definition
1. dehydrogenation
2. hydration
3. dehydrogenation
4. cleavage
Term
How are dietary fatty acids transported in the blood?
Definition
FA's are transported via chylomicrons (lipoproteins). They are released by a LIPOPROTEIN LIPASE
Term
Fatty Acids stored in adipocytes are released by hormone sensitive lipase. What hormones regulate this enzyme?
Definition
Glucagon (+)
Insulin (-)
Term
How are fatty acids released from adipocytes transported in the blood?
Definition
When released from adipocytes they are bound to serum albumin in the blood
Term
Free fatty acids (when really free) act like what, in the cell?
Definition
Actually *free* fatty acids act like detergents and are bad for cell membranes
Term
Before fatty acids can be oxidized they must be ______ for reaction in an ATP dependant acylation reaction to fom _________
Definition
1. primed
2. acyl-CoA
Term
Where does the 'priming' (conversion of FA to acyl-CoA) of fatty acids occur?
Definition
Fatty acids are primed- turned inot acyl-CoA- in the outer mitochondrial membrane, by 'fatty acyl-CoA synthetase'
Term
What makes the creation of acyl-CoA from fatty acid an irreversible reaction?
Definition
The cleavage of PPi to 2Pi drives the reaction forward
Term
FAs are converted to acyl-CoA on the outer mitochondrial membrane. What is the mechanism for the acyl-CoA to cross the inner mitochondrial membrane?
Definition
transport steps:
1. carnitine acyl transferase I (CAT1) regulated step
2. Translocase
3. Carnitine acyl transferase II (CATII)

(note that the CoA does not actually cross the membrane, but is replaced by carnitine, and once the molecule crosses the border, is switched back to CoA)
Term
List the four repeated steps of B-oxidation and the enzymes that catalyze them.
Definition
1. Dehydrogenation (acyl CoA dehydrogenase)
2. hydration (enoyl CoA hydratase)
3. dehydrogenation (B-hydroxy acyl COA dehydrogenase)
4. cleavage (B-ketothiolase)
Term
What are the products of a completely B-oxidized palmitate (16C) molecule?
Definition
B-oxidation of palmitate would result in:
8 acetyl CoA
7 FADH2
7 NADH+H+
(and requires 7 cycles of oxidation)
Term
The special case problem of an acyl-CoA with double bonds between carbons 3-4 (instead of the normal 2-3) can be resolved by what enzyme?
Definition
Enoyl CoA isomerase - can move the double bond from 3-4 to 2-3. (Also, it should be a trans double bond)
Term
Polyunsaturated acyl-CoA (more than one double bond) requires which two enzymes?
Definition
It requires a reductase in addition to the enoyl CoA isomerase
Term
Odd numbered carbon chains (ex. C17) require what special measures for oxidation?
Definition
1. The last round of B-Oxidation leaves a 3 carbon group called propionyl CoA
2. Propionyl CoA can be converted into succinyl CoA (and then enter the TCA cycle), but it requires ATP and vitamin B12. The enzyme used is methylmalonyl CoA mutase.
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