Lipid Anabolism Flashcards
Which intermediate of glycolysis is used as the glycerol backbone in lipid synthesis?
DHAP gets converted into glycerol and is used as the backbone in triacylglyercol synthesis
In what tissues is fatty acid synthesis prodominently take place?
Liver and adipose tissue
Function of Lipids
Fuel stores
Structural component
Signaling molecules
Temperature homeostasis
What form of lipid in the body is fat stored?
Triacylglycerol
Where is the body are triacylglycerol mostly stored
Adipose tissues
Where in the body does beta-oxidation occur?
Liver
How many phases of fatty acid synthesis?
Three
Phase 1 - Cytosolic Entry of Acteyl-CoA
Phase 2 - Generation of Malonyl-CoA
Phase 3 - Fatty acid chain formation
What is the rate-limiting step in Fatty Acid Syntheis
Generation of Malonyl-CoA
Carboxylase (adds CO2) Acetyl-CoA to create Malonyl-CoA
How does Aceytl-CoA get from the mitochondria into the cytoplasm
Citrate Transport
Acetyl-CoA is combine with oxaloacetate into citrate
Citrate is then transported into the cytosol from the mitochondria
Acetyl-CoA and OAA are then regenerated in the cytoplasm
What controls ATP Citrate Lyase?
Activates - Glucose, Insulin (fed state)
Inactivates - PUFA, leptin (full/too fat state)
ATP Citrate Lysases converts Citrate back into Acetyl-CoA and OAA in the cytosol
What enzyme converts Citrate back into Acetyl-CoA and OAA in the cytosol?
ATP Citrate Lyase
What happens to the OAA after Acetyl-CoA is recreated back in the cytosol?
OAA ⇒ Malate ⇒ Pyruvate
Function and Control of Aceytl-CoA Carboxylase
Carboxylate Acetyl-CoA into Malonyl-CoA
Rate-limiting step in Fatty Acid Synthesis
Activates - citrate, insuline (fed state)
Deactivates - Glucagon (fasting), epinephrine (exercise), high [AMP], PUFA, Palmitate
Coenzyme for Acetyl CoA Carboxylase
Biotin - Vit B9
Importance of Malonyl-CoA
Substrate of Fatty Acid Synthesis
Inhibits Carnitine Acyltransferase (rate-limiting step of Fatty Acid Degradation)
Helps prevent degradation during synthesis
To make palmitate how many malonyl-CoA are required?
7 Malonyl-CoA
How many NADPH are oxidized per palmitate?
14 NADPH
Order of Reactions in Fatty Acid Synthesis
Condensation
Reduction
Dehydration
Reduction
Mnemonic: C ouR DR
What reducing power does FAS require?
NADPH
Sources of NADPH
Malic enzyme - 1
Pentose phosphate pathways - 2-12
Regulation of Phase I of FAS
ATP Citrate Lyase
Activation (Dephosphorylated) - Citrate, Insulin,
Deactivation (Phosphorylate) - Long-chain fatty acids, epinephrine, glucagon, high [AMP]
Conditions Increase Synthesis
High carb/low fat dies
Insulin and glucocoritcoid hormones
Conditions that decrease FAS
High amounts of PUFA, high fat diets, starvation
Where does elongation of parmitate occur in the cell?
Smooth ER or Mitochondria
Smooth ER uses Malonyl-CoA as source of carbon
Mitochondria uses Acetyl-CoA as carbon donor
