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Fatty Acid Oxidation
EXAM 2
62
Medical
Professional
08/31/2010

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Term
what is the structure of a FA?
Definition
long hydrocarbon chain and a terminal carboxylate
Term
which is a more efficient form of energy: TAG or glycogen
Definition
TAG
Term
what is the major energy source in cardiac and skeletal muscle?
Definition
FA's
Term
Why does the brain not utilize FA's?
Definition
FA's cannot cross the blood brain barrier
Term
what is the site of fatty acid oxidation?
Definition
mitochondria
Term
what happens when the hormone lipase is released?
Definition
in adipose tissue,hydrolysis of TAG to FA's.
Term
when FAs are released into the blood, how does it travel
Definition
bound to albumin
Term
how are FA's transported inside the cell
Definition
FA transporters
Term
in the cells, how is acyl-CoA formed for B-oxidation
Definition
FA are conjugated w/CoA
Term
what is perilipin?
Definition
protein that coats the lipid droplet
Term
what is the function of phosphorylated perilipin?
Definition
promotes translocation of lipase to lipid droplet for hydrolysis of FA
Term
what is the effect of glucagon, epinephrine and ACTH on TAG metabolism?
Definition
it activates the release of free fatty acids from triglycerides
Term
what is the effect of insulin on TAG metabolism
Definition
inhibition
Term
what is the name of the enzyme that catalyzes a FA to FA acyl-CoA
Definition
acyl CoA synthetases
Term
where is FA and FA acyl CoA converted?
Definition
outer mitochondrial membrane and ER
Term
does the formation of fatty acyl-CoA require ATP?
Definition
yes. the hydrolysis of two high energy bonds in ATP
Term
what is function of carnitine palmitoyltransferase I?
Definition
transports FA to the mitochondrial inner membrane
Term
what is the function of translocase?
Definition
it takes the intermediate Acylcarnitine into the inner membrane.
Term
what effect does malonyl-CoA have CTP and FA oxidation
Definition
it inhibits CTP, thus preventing FA oxidation in the fed state.
Term
what does the beta oxidation of FA require?
Definition
successive cleavage of 2 C w/release of acetyl CoA
Term
which FA's diffuse through the membrane
Definition
short and medium chain FAs
Term
which FA transports through the Carnitine cycle?
Definition
Long chain FA
Term
which FA transports through the Carnitine cycle?
Definition
Long chain FA
Term
what are the three substances that are collectively known as ketone bodies?
Definition
acetoacetone, beta-hydroxybutyrate, acetone
Term
this is an important intermediate in the synthesis of cholesterol
Definition
HMG-CoA
Term
name 4 things that ketone bodies are used for
Definition
heart, brain, kidney, skeletal muscle
Term
ketone bodies are synthesized to produced
Definition
2 acetyl coA going into the TCA cycle
Term
the hydrolysis of triglyceride in adipose tissue produces this, which eventually leads to glucose
Definition
free glycerol
Term
what does the liver synthesize glycerol to? by what enzyme?
Definition
glycerol 3 phosphate by glycerol kinase
Term
what is glycerol 3 phosphate converted to in the liver to undergo gluconeogenesis
Definition
dihydroxyacetone
Term
where does omega oxidation of FA occur?
Definition
in the ER with involvement of cytochrome P450
Term
what is the prevalent pathway after beta oxidation of FA is defective?
Definition
omega oxidation
Term
in omega oxidation, what is introduced on the first step?
Definition
hydroxyl
Term
What is the hydroxyl group oxidized to on the omega carbon?
Definition
aldehyde and then carboxylic acid
Term
what is the end product of omega oxidation?
Definition
dicarboxylic acid
Term
what is associated with secondary carnitine deficiency?
Definition
defects in the beta oxidation pathway w/accumulation of acylcarnitines, which are secreted in teh urine
Term
what are some clinical manifestations of primary carnitine deficiencies?
Definition
muscle cramping, muscle weakness
Term
what is caused by a primary carnitine deficiency
Definition
defect of carnitine transporter
Term
what mutation causes CPT
Definition
mutation of the CPTII gene
Term
what are the clinical manifestations of CPT deficiency?
Definition
muscle weakness during prolonged exercise with loss of myoglobin in the urine
Term
how are translocase deficiencies treated?
Definition
avoidance of fasting and diet supplemented by medium chain FA
Term
what are the clinical symptoms of translocase deficiency
Definition
hypoglycemic coma, hyperammoniemia, muscle weakness, cardiomyopathy
Term
these inherited disorders affect the first reaction in the B-oxidation of FA
Definition
acyl CoA dehydrogenase deficiency
Term
what type of dehydrogenases are affected in acyl-CoA dehydrogenases?
Definition
short, medium, and very long chain dehydrogenases
Term
what is hypoketotic hypoglycemia due to?
Definition
a block of B oxidation of FA's which slows gluconeogenesis in the liver.
Term
what is dicarboxylic aciduria due to?
Definition
accumulation of FA that enter alternative degration pathways such as omega oxidiation. excessive secretion of dicarboxylic acids
Term
what is sudden infant death due to?
Definition
MCAD deficiencies
Term
where does oxidation of very long chain FA occur?
Definition
peroxisomes
Term
what XALD due to
Definition
failure to oxidize long chain FA
Term
What is Zellweger syndrome
Definition
inability to make peroxisomes
Term
Patients w/zellweger syndrome and XALD have accumulation of what in the blood?
Definition
very long chain FA
Term
This antidiabetic drug causes a marked increase in
Definition
peroxisomes
Term
beta oxidation in the peroxisome of very long chain FA produces
Definition
Octanoyl-CoA
Term
With odd-chain FA metabolism via Beta oxidation, what is the product most likely to be?
Definition
3 Carbon product
Term
where does Alpha oxidation of FA occur?
Definition
ER, mitochondria, peroxisomes.

also involves mono oxigenases (P450 family) that use NADH or NADPH
Term
what is alhpa oxidation important for?
Definition
catabolism of branched chain FA
Term
what are the products of alpha oxidation of FA?
Definition
3 mols of propionyl-CoA, acetyl CoA and one molecule of isobutyrl CoA
Term
what is involved in the reaction of phytanoyl CoA being hydroxylated?
Definition
a-ketoglutarate, ascorbate, and iron
Term
Refsum's disease is characterized by?
Definition
lack of a-hydroxylating enzyme and accumulate phytanic acid
Term
what will insulin stimulate in the fed state?
Definition
FA synthase, NADPH malic dehydrogenase, and acetyl CoA carboxylase
Term
what enzymes do insulin stimulate in the fed state
Definition
glut 4 translocation, glucose breakdown to glycerol 3-phosphate for synthesis of TAG.

turns on phosphoprotein phosphatase (removes phosphate from acetyl CoA and activates enzyme)

also stimulates pentose pathway w/generation of NADPH
Term
what is the effect of glucagon in the fasted state?
Definition
they inhibit acetyl-coA carboxylase, decreasing FA synthesis
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