FINAL Fatty acid synthesis and degradation Flashcards
What are the FOUR physiological roles of Fatty acids?
- Fuels molecules- triacylglycerols
- Building blocks of Biomembranes
- covalent modification of certain proteins
- serve as hormone or intracellular receptors
fatty acids can be stored as what molecule that serves as the primary source of our body’s energy?
triacylglycerols
In regards to Fatty acid synthesis and degradation do they mirror each other?
Yes
In fatty acid synthesis, the Activated Acyl group is lengthened by how many carbons ?
Two carbon atoms
In fatty acid degradation, the Activated Acyl group is shortened by how many carbons?
Two carbon atoms
In regards Fatty acids: oxidation, hydration, and cleavage are all a part of what process
Fatty acid degradation
In regards to Fatty acid: condensation, reduction, dehydration, reduction?
Fatty acid Synthesis
When we degrade a 1 Fatty acid, the product, that is a precursor for the TCA cycle is?
Acetyl COA
Where can we get fatty acids?
we get them from degraded triacylglycerol
Triacylglycerols can be found in?
Fat deposits/droplets
Why are Triacylglycerols represented as highly concentrated energy reserves?
Because fatty acids are much more reduced and anhydrous.
What allows Triacylglycerols to be stored in anhydrous form.
b/c Its non-polar nature, energy-rich molecules can be packed in small volumes
what is the lowest fuel reserve in our body?
Glucose 170 kJ
Highest fuel reserve in our body
Triacylglycerols 420,000 kJ
Glucose and glycogen reserves contain enough energy for how long?
used up in approximately 24 hours
how long do triacylglycerols contain sufficient energy for in a scenario of being stuck in a desert with only water?
50 days
In mammals what is the specialized tissue called that is the main site for the synthesis, storage, and mobilization of fat droplets?
Adipose tissue
Adipose tissue can be found almost everywhere, but mainly in what depots?
Subcutaneous and visceral depots
Where can you find commonly an accumulation of adipose tissue?
heart, kidneys, and the adventitia of blood vessels
most dietary lipids are ingested in the form of what?
Triacylglycerols
Dietary lipids are digested by what enzyme and where is it produced?
Pancreatic lipases
What do lipases do to Triacylglycerols?
They hydrolyze Triacylglycerols into free fatty acids and monoacylglycerol.
For Triacylglycerols to be absorbed by intestinal epithelium they require what step?
degradation to fatty acids
Why do Triacylglycerols coalesce into droplets inside in adipose tissue and stored anhydrously?
b/c they are insoluble in water, Hydrophobic
in what are dietary lipids transported in?
Chylomicrons
Chylomicrons are what?
Lipoprotein transport particles
What is the main protein component in Chylomicrons?
apolipoprotein B-48
apolipoprotein B-48 is used for what ?
transport of fat soluble vitamins and cholesterol.
When we eat from our diet we get triacylglycerols what is the process of it going to the lymph system?
- Triacylglycerols are degraded by lipases in the lumen -> Fatty acids + monoacylglycerol
- both are carried into the intestinal cell via FABP ( Fatty acid binding protein)
- fatty acid transport protein ( FATP) transfer them into the SER ( smooth ER)
- In a smooth ER FA’s resynthesize triacylglycerol
- triacylglycerol is enveloped by chylomicrons
- TAG+ Chylomicrons are released to the lymphatic system.
what are the requirements of processing for the utilization of Fatty acids for fuel in peripheral tissue?
- Mobilization
- Activation and localization
- degradation
In peripheral tissue what occurs in the mobilization process?
triacylglycerol is hydrolyzed into constituents molecules and transported to energy required tissues
In peripheral tissue what occurs in the activation and localization process?
The fatty acids are transported to mitochondria for degradation
In peripheral tissue what occurs in the degradation process?
Fatty acids are broken down, step-by-step, into acetyl-CoA. This intermediate is oxidized by the TCA cycle
Triacylglycerols are stored in
lipid droplets in adipocytes
Triacylglycerols are Hydrolyzed by
Hormone-Stimulated Lipases- HS lipase and Perilipin
What stimulates lipolysis?
Epinephrine or glucagon that acts on a 7TM receptor
Protein kinase A phosphorylates what hormone stimulated lipases?
perilipin and HS lipase
Phosphorylation of perilipin results in the activation of?
adipocyte triacylglyceride lipase (ATGL) after binding of its coactivator
HS lipase and ATGL work together to hydrolyze TAG into what constituent molecules that are transported to energy requiring tissues
Fatty acids and glycerol
Fatty acids are not soluble in aqueous solutions. To reach tissues that require fatty acids, the released fatty acids bind to what blood protein?
albumin
What happens to the glycerol that was a resulted of the hydrolysis of triacylglycerol?
- absorbed by the liver and immediately phosphorylated by glycerol kinase.
product: L-glycerol-3-phosphate - L-glycerol-3-phosphate is oxidized by glycerol phosphate dehydrogenase.
product: dihydroxyacetone phosphate - it is isomerized to glyceraldehyde-3-P
- later process by gluconeogenesis or glycolysis
To begin fatty acid degradation Fatty Acids are Linked to what molecule before they are oxidized?
esterified to acyl-CoA
What enzymes esterifies fatty acids to acyl-coA
acyl-CoA synthetase
how many ATP’s are used in equivlance to make acyl-coA?
2
Fatty acids are activated on what part of the mitochondria?
Fatty acids are activated on the outer mitochondrial membrane
Why do fatty acids need to be in the mitochondrial matrix?
for oxidation
integrity of the inner mitochondrial membrane must be maintained, fatty acyl-CoA transport requires a specialized mechanism that entails what?
- the fatty acyl-CoAs are conjugated to carnitine to form an acyl-carnitine intermediate.
catalyzed: carnitine acyl-transferase I. - The acyl-carnitine intermediate is shuttled across the inner mitochondrial membrane through by acylcarnitine translocase
3.when the acyl-carnitine is in the mitochondrial matrix, it can be re-esterified to CoA through the action of carnitine acyl-transferase II.
What happens to the regenerated carnitine molecule after it disassociates with acyl coA?
translocated to the cytoplasm to begin another round of transport.