Chapter #27: Fatty Acid Oxidation Flashcards
(31 cards)
What are the three steps of processing the triglycerides stored in adipose tissues?
- Mobilization
- Activation
- Degradation
What happens in fasting and exertion states?
glucagon and epinephrine transduce a signal which activates perilipin A to restructure fat droplets, and hormone-sensitive lipase to hydrolyze the triglyceride to free fatty acids/
What is the carrier for released fatty acids in the mobilization step?
Since the released fatty acids are not soluble in blood, the serum protein albumin serves as a carrier
What happens to the glycerol formed in the triglyceride hydrolysis?
It is not wasted, it is absorbed by the liver and converted to GAP for use as energy in glycolysis or glucose production in gluconeogenesis
What is a source of NADH?
The oxidation of glycerol 3-phosphate is another source of NADH
Why is glycerol the only source of net carbon from triglycerides?
the rest of the triglycerides is fatty acids – which are burned to CO2 in the citric acid cycle
What do free fatty acid typically travel with?
serum albumin
Where does the glycerol from the triacylglycerol go in the body and into which pathway?
liver cell
glycolysis -> pyruvate
gluconeogenesis -> glucose
Where do the fatty acids from the triacylglycerol go in the body and into which pathway?
other tissues
fatty acid oxidation –> acetyl CoA –> CAC –> CO2 + H2O
What is the overall equation for the activation step of Fatty Acid Oxidation?
What does the conversion of ATP down to AMP mean?
two high energy phosphates were consumed
What are the two steps of turning a fatty acid into Acyl CoA?
- ATP reacts with the fatty acid and pyrophosphate is released.
- The sulfhydryl of CoA attacks the acyl adenylate to form acyl CoA and AMP.
How do acyl groups get across the mitochondrial membrane?
To get across the inner mitochondrial membrane, the acyl groups are temporarily attached to the zwitterionic alcohol carnitine, translocated across the membrane, and then returned to CoA
What kind of fatty acids need the carnitine shuttle to cross the inner mitochondrial membrane?
only long chain fatty acids (C16 and longer) require the carnitine shuttle to cross the inner mitochondrial membrane – medium chain (C8-C14) and short chain fatty acids (C8 or less*) can pass through on their own.
*The exact ranges for what are considered “long”, “medium”, or “short” chain fatty acids can vary with the circumstance and should just be considered relative.
What are the steps of degradation in fatty acid oxidation?
Oxidation: Double bond introduced
Hydration: Introduces a hydroxyl group
Oxidation: Converts the hydroxyl to a ketone
Cleavage: Creates acetyl CoA + fatty acyl-CoA (n-2)
What energy-containing compounds are we making in the process of fatty acid oxidation?
1 FADH2
1 NADH
1 Acetyl CoA
What is the energy yield from fatty acids?
2.5 molecules of ATP per NADH produced
1.5 molecules of ATP per FADH2 produced
10 molecules of ATP per acetyl CoA produced
How many ATP are created for palmitate? (C16; 7 turns, 8 acetyl-CoA)
7 x 2.5 ATP/NADH = 17.5 ATP
7 x 1.5 ATP/FADH2 = 10.5 ATP
8 x 10 ATP/Acetyl CoA = ATP 80
Activation of palmitate = -2 ATP
Overall: 106 ATP
Where does synthesis take place?
in the mitochondria of lover cells
What are the 3 types of ketone bodies and their properties?
acetoacetate, D-3-hydroxybutyrate and acetone
What are the normal fuels of respiration?
Acetoacetate and 3-hydroxybutyrate are normal fuels of respiration, important sources of energy, and heart muscle/renal cortex even prefer them as fuel over glucose.
What does brain and RBCs prefer for fuel?
Brain and RBCs prefer glucose for fuel, but the brain will switch to ketone bodies (75%) in prolonged starvation.
How do acetoacetate and hydroxybutyrate differ?
Acetoacetate and hydroxybutyrate simply differ in the oxidation state at 1 carbon
What presents in the blood of untreated diabetics?
Abnormally high levels of ketone bodies are present in the blood of untreated diabetics – acetone can be detected in people who have a high level of acetoacetate in the blood.
