MBOD Block 4 Week 3 Flashcards
Where are fats primarily stored?
In adipose tissue
How are fatta acids oxidized?
By B-oxidation pathway in mitochondria
What is the path of dietary fatty acids?
They are carried from the intestine to tissues to be metabolized as part of chylomicrons.
What is the path of stored fatty acids?
They are released from storage (lipolysis), and transported bound to serum albumin to be oxidized.
Which bond is cleaved in B-oxidation?
The alpha-beta bond.
What is Linolenate?
An 18 C FA with 3 double bonds (polyunsaturated); omega-3,6,9FA; Can also be called a cis delta-9,12,15 Octadecatrienoate.
Where do glucose and triglycerides from the diet or from the liver release go?
To make TG.
What are the stores of TG released as upon hormonal signals?
FA + Glycerol.
What do lipolytic hormones do?
Increases adipocyte cAMP and activation of lipase. Serum free fatty acid levels increase.
What are some lipolytic hormones?
Glucagon and Epinephrine
What is a antilipolytic hormone?
Decreases adipocyte cAMP. Decreased serum free fatty acid (FFA).
What is the major antyilipolytic hormone?
Insulin
What does a lack of insulin result in, esp in Type 1 diabetes?
Excessive lipolysis leading to ketoacidosis.
How do FA come into the muscle cell?
Carried on FA-albumin in the blood after the release by fat.
What are the activated transport intermediates in mitochondrial long-chain FA metabolism.
FACoA and FA carnitine
What are FACoA in the mitochondrial matrix oxidized to?
FAD2H, NADH, and AcCoA, which feed into the TCA and ETC or are made into Ketone bodies
How many carbons are in a short chain FA?
2-4
What type of membrane transport do short chain FA use?
Free diffusion
What type of membrane transport do medium chain FA use?
Diffusion
How many carbons are in a medium chain FA?
4-12
How many carbons are in a long chain FA?
12-20
What type of membrane transport do long chain FA use?
Carnitine cycle
What is the site of catabolism for very long chain FA?
Peroxisome
How many carbons are in a very long chain FA?
> 20
What are the metabolic routes for Fatty acyl CoA?
Energy, Membrane lipids, Storage
What is the role of Carnitine?
It carriers FA bound to it into the mitochondria.
What are the enzymes that reversibly transfer FACoA and FAcarnitine?
CPT1 and CPT2 (Carnitine palmitoyl-transferase I and II)
What facilitates the exchange of carnitine and acyl-carnitine?
Carnitine acylcarnitine Translocase
What is the first step of B-oxidation and the enzyme used?
Oxidize to double bond. Acyl CoA Dehydrogenase
What is the product of the first step of B-oxidation?
trans Fatty enoyl CoA
What is the second step of B-oxidation and the enzyme used?
Hydration adds -OH and -H across bond. Enoyl CoA hydratase
What is the product of the second step of B-oxidation?
L-B-Hydroxy acyl CoA
What is the third step of B-oxidation and the enzyme used?
Oxidize to double bond; C-OH=>C=O. B-hydroxy Acyl CoA Dehydrogenase
What is the product of the third step of B-oxidation?
B-Keto acyl CoA
What is the fourth step of B-oxidation and the enzyme used?
Cleaved (thiolysis). B-keto thiolase
What is the product of the fourth step of B-oxidation?
2 C shorter FACoA and AcCoA.
What are the similar processes between B-oxidation and the CAC?
Hydration, production of FADH2 and NADH
Where do the electrons from fatty acid oxidation go to; and what are the enzymes used?
The ETC. Acyl CoA dehydrogenase, Electron transferring flavoprotein (ETF), ETF-CoQ oxidoreductase.
How much does 1 palmitate undergoing 7 cycles of B-oxidation yield?
7 FADH2, 7NADH, 8AcCoA
How many ATP are produced by the 7FADH2 and 7 NADH?
28 ATP
How many ATP are produced by 8 AcCoA?
80 ATP
What is the net ATP yield from B-Oxidation?
106 ATP/palmitate
What is CPT1 inhibited by?
Malonyl CoA
What is the major control of FA oxidation?
Availability of FA
What occurs with oxidation of unsaturated FA?
The unconjugated double bonds are moved so that it becomes a conjugated double bond in the trans configuration.
What prevents double bonds from interferring with B-oxidation?
The isomerase and reductase working together.
What is the product of odd-chain FA oxidation?
Propinyl CoA and Acetyl CoA
What forms propionyl CoA?
The final thiolysis step in the oxidation of odd chain FA.
What are the two vitamins that are required for the metabolism of Propionic Acid?
Biotin and B12
What is the end product of the metabolism of Propionic Acid?
Succinyl CoA ->to CAC
What is Zellweger syndrome?
Lack of functional peroxisomes; defective import of proteins; VLCFA acumulate; liver kidney, and muscle damage.
What is formed from the oxidation of VLCFAs?
H2O2 and NADH
How long does the peroxisome oxidation of VLCFA repeat until?
Until there are 6-10 Carbons.
What is the result of Alpha-oxidation of branched chain FA?
PropCoA or AcCoA; repeats until the chain is 8C.
What does the branched chain FA that has been oxidized go to the mitochondria as?
FA-carnitine
What is Refsun’s Disease?
A rare neurological disorder caused by defective alpha-oxidation. Phytanic acid is deposited in nerve tissue.
What does omega-oxidation convert FA to?
Dicarboxylic acids
What is the fate of dicarboxylic acids after omega-oxidation?
They may be excreted or conjugated to glycine or carnitine.
What is the treatment for disorders of FA Oxidation?
Avoid fasting; more smaller meals; less fat; provide energy needs with carbs-controls lipolysis and decreases dependence on fats and ketones for energy.
What does the B-oxidation of “even chain” FA in the mitohondria produce?
AcCoA, FADH2, and NADH
What does the B-oxidation of “odd chain” FA in the mitohondria produce?
FADH2, NADH, AcCoA, and propionyl CoA ->succinyl CoA
What does the B-oxidation of unsaturated FA in the mitohondria require?
Two extra enzymes, an isomerase and a reductase to modify the double bonds.
What do peroxisomes specialize in?
Very long and long-chain fatty acids (n>8).
What do peroxisomes produce?
AcCoA, FADH2, and H2O2.
What are branched-chain phytanic acids oxidized by?
Alpha-oxidation
What does alpha-oxidation do?
It removes one carbon from the carboxyl end.
What does B-oxidation alternately release in peroxisomes when dealing with branched-chain phytanic acids?
AcCoA and Propionyl CoA until the chain reaches 8 C, then it leaves the peroxisome as fatty acyl-carnitine.
Where does omega-oxidation occur?
In the ER.
What can accumulate abnormally in omega oxidation if B-oxidation is defective?
Dicarboxylic acids
What is the main thing that is occuring in the Fed State?
Glucose, FA, AA is used for fuel or stored.
What is the main thing that is occuring in the Fasted State?
Fat starts breaking down TG to FA and glycerol
What is the main thing that is occuring in the Basal Fasted State?
Fat releases FA which is used for energy and Ketone Body synthesis.
What is the main fuel source in the Starved State?
FA
Whatbecomes fuel for the brain in the Starved State?
KB
What are the key fuels in the fasting state?
Ketones
Where is HMG CoA synthase found?
In liver mitochondria
Where are ketones only made?
In the liver