Fat Metabolism Flashcards
What is the basic structure of tags
A glycerol backbone and 3 fatty acid chains
What is the basic pathway for fat breakdown in a cell
The tag will be broken down into a glycerol and fatty acid.
The glycerol can be used to generate new glucose via gluconeogenesis in the liver
The fatty adds can undergo fatty auld oxidationor ßoxidation in muscle, liver, or other tissues
What is the difference between acyl coa and acetal coa
Acetal COA is 2 molecules bound to con whereas acyl has a longer chain
T/F. Acyl chains are trapped in the cell by covalent addition of coenzyme A
True
What must be done to release acyl chains from the cell and be used in the cytoplasm
Acyl COA synthatase catalyzes a reaction to form fatty and acyl COA
What drives the synthetase reaction forward
Pyrophosphate hydrolysis (ATP - amp)
What kind of reaction is a acyl coA synthatase
Ligase
Isn’t more favorable to convert ATP to ADP or to amp? Why?
It is easier to convert ATP to ADP because there must be a second ATP present to first convert the amp to ATP
Describe the reaction needed to generate ATP from amp
Amp is converted into ADP via adenylate kinase and an ATP molecule will de sacrificed and form a second ADP molecule.
ATP synthase which can only bind to ADP will produce 2 ATPs
What is needed for fatty acid activation
2 ATPs (1 for activation and one for production of ADP) and 1 water to hydrolyze PPi
Where does ß oxidation take place
Mitochondrial matrix
T/F. Acyl con can move across the outer and inner membrane.
False acyl coa can only move across outer membrane via porins. There are no transporters in the inner membrane to transport acyl coa and it is too large and water soluble
Carnitine shuttle
Mechanism used to indirectly get acyl coa across membrane
It will regulate what comes into the mitochondria and whether we are breaking COA chains
Describe how acyl coa enters the matrix
Carnitine acyltransferase 1 transfers act to a Carnitine , which will then be translated across the inner membrane while a new Carnitine gets shuttled out.
Carnitine acyltransferase 2 moves acyl back onto COA
Acyl esa can then be catabolized in ß oxidation
How many rounds of oxidation are needed to breakdown 16:0 COA
Use formula (n/2-1)
You would need 7 rounds ,
For each round of ß oxidation what is being consumed/produced
1 water and COA is being consumed
1 NADH, FADH, AND Acetyl CoA is produced
What hormones are required for tag breakdown
Epinephrine and glucagon
How does fatty acids move to the blood
They are bound to serum albumin and enter tissue
How many ATP, are required to move fatty acids in the cytoplasm
2
What is the rate limiting step in the citric acid cycle
Oxalacetate, because in order to start the CAC acetal coa must combine with oxaloacetate
To produce citrate
What are the different ways oxalacetate can be made
By amino acids or pyruvate by enzyme pyruvate carboxylase
Explain the 3 steps in fat synthesis
- Acetal coa is transported to the citric acid cycle where it will be converted into citrate to cross the membrane via citrate synthase it will then be converted back into acetal COA regenerating a pyruvate molecule
2.acetylco A is carboxylated by acetal co A carboxylase using ATP to form malonyl COA - Malonyl COA will be used to make the 16:0 fatty acid chains
What is the significance of the CO2group on malonyl coa
It will help drive the fatty acid synthesis reaction forward
What 2 enzymes are needed for fatty acid synthesis
Acetal coa carboxylase for conversion to malonyl coa and fatty acid synthase
What does acetal esa carboxylate use as its reducing power? FA synthase?
ACC uses ATP
Fa uses nadph
Regulatory steps for fat synthesis
ACC is regulated by PTM phosphorylation.
When ACC is phosphonylated by kinase it is inactivated. This happens in the catabolic state when epinephrine and glucagon signaling is on
In the anabolic state, insulin activates phosphates which will dephosphorylate ACC turning it on citrate can also stimulate ACC
Describe the competitive regulatory processes in fat metabolism
Malonyl Col, product of conversion of acetal COA by ACC can inhibit CATI, preventing the conversion of acyl COA to acyl Carnitine trapping it in cytoplasm
Describe the competitive regulatory processes in fat metabolism
Malonyl Col, product of conversion of acetal COA by ACC can inhibit CATI, preventing the conversion of acyl COA to acyl Carnitine trapping it in cytoplasm
In step 3 of FA synthesis, what is the purpose of acyl carrier protein (acp)
It shuttles the intermediates between different reaction sites
How many cycles are required for FA synthesis of 16:0
7 cycles (n/2-1) with acetyl coA and malonyl coA for cycle 1 and 6 more malonyl for the other cycles
How much energy is used for FA synthesis
7 ATP and 14 NADPH
