E3 Fatty Acids and Lipolysis Flashcards
which fatty acids cannot be synthesized by the body?
linoleic and alpha linolenic
match the nomenclature to the fatty acid.
- stearic acid
- oleic acid
- linoleic acid
- linolenic acid
A. 18:1w9
B. 18:3w3
C. 18:0
D. 18:2w6
- C
- A
- D
- B
match the nomenclature to the fatty acid.
- arachidonic acid
- EPA
- DHA
- Palmitic acid
A. 16:0
B. 20:5w3
C. 20:4w6
D. 22:6w3
- C
- B
- D
- A
what are fatty acids stored as?
TGs
what are TG’s stored in?
lipid droplets
when fatty acids are stored as TGs, what type of bonds are made? what is the backbone?
ester bonds
glycerol backbone
T/F. Lipid droplets are extracellular organelles within the cytoplasm.
false; intracellular
what are three reasons why TGs are stored in lipid droplets?
- energy
- membrane synthesis
- protect against lipotoxicity
define lipolysis.
breakdown of TG to mobilize FAs (3 FFAs and glycerol)
T/F. Lipolysis can occur in the GI, vascularly, and intracellularly.
true
what are the three lipases in GI lipolysis?
lingual, gastric, and pancreatic
where does digestion begin?
mouth and stomach
most dietary TAGs breakdown in
A. mouth
B. stomach
C. small intestine
C. small intestine
T/F. Lipases cleave ester bonds.
true
what protein as considered the “gate keepers” of regulating lipid metabolism?
perilipins
what are the contents of lipids that enter the enterocyte?
FFA, MAG, DAG, cholesterol, cholesterol esters
______ is formed at the enterocyte and transports dietary lipid and cholesterol.
chylomicrons
other than chylomicrons, what are the other lipoprotein complexes?
VLDL, HDL, LDL, IDL
as the chylomicron slowly enters the blood, the lipid from the diet goes to what type of tissue?
extrahepatic tissue (adipose and muscle)
when is the chylomicron sent to the liver?
as the TG is removed at the target cell and becomes a chylomicron remnant
MCFA –> lymph –> blood –> liver via what protein?
albumin
LCFA –> lymph –> blood –> adipocyte –> liver via what lipoprotein complex?
chylomicron
define vascular lipolysis.
breakdown of TGs from certain lipoprotein complexes
what lipase is used during vascular lipolysis?
Lipoprotein Lipase (LPL)
is lipoprotein lipase (LPL) extracellular or intracellular?
extracellular
what is the location of LPL?
endothelial surface of capillaries
T/F. during exercise, there is a decrease concentration of LPL in skeletal muscle.
false; increased LPL
when you do not exercise, LPL concentration decreases by how much in skeletal muscle?
10-20 fold
what is the reason for LPL production at target cells in muscle? adipose?
M= FA oxidation for energy A= re-esterified to be stored as TGs
define intracellular lypolysis.
breakdown of TGs located in intracellular lipid droplets
what are the three intracellular enzymes associated with intracellular lipolysis?
adipose triglyceride lipase (ATGL)
hormone sensitive lipase (HSL)
monoacylglycerol lipase (MGL)
match the rxn to the enzyme.
A. ATGL
B. HSL
C. MGL
- MAG –> FFA +glycerol
- TAG –> DAG
- DAG –> MAG
A. 2
B. 3
C. 1
which intracellular enzyme is the key regulatory enzyme in intracellular lipolysis? why?
HSL; lipolysis is regulated by hormones= glucagon and epinephrine
intracellular lipolysis is regulated by hormones and triggers the cAMP cascade. what type of regulation is this?
covalent modification
what will stimulate ATGL?
glucocorticoids
epinephrine
fasting
what will inhibit ATGL?
insulin
food intake
what will strongly stimulate HSL?
B-adrenergics (epinephrine, norepinephrine, phosphorylation)
glucagon
what will strongly inhibit HSL?
insulin
T/F. There is more information on what stimulates and inhibits MGL than ATGL and HSL.
false; not much is known
when epinephrine/glucagon bind to the PM and initiate the cAMP cascade, what will PKA phosphorylate and activate?
perilipin and HSL
when perilipin is phosphorylated and activated by PKA, what enzyme will become activated?
ATGL
when HSL is phosphorylated and activated by PKA, what enzyme will become activated?
MGL
what hormone will inhibit phosphorylation of perilipin and HSL, therefore inhibiting lipolysis?
insulin
when FFA from ATGL, HSL, MGL is released into the blood and transported to target tissues, what protein is it bound to? how many FFA can it carry?
albumin; apx 10 FFAs
what enzyme will convert glycerol to G-3-P?
glycerokinase
T/F. There is a lot of glycerokinase in adipose.
false; absent in adipose
once glycerol is converted to G-3-P via glycerokinase, what will G-3-P become? what two pathways can it enter?
DHAP; glycolysis and GNG
lipolysis of stored TGs in an adipocyte results in 3 FFAs and glycerol. where will the glycerol go? FFAs?
glycerol –> hepatocyte
3FFAs –> target cells (e.g. muscle)
matching.
A. convert to DHAP B. B-oxidation C. make ATP D. enter glycolysis and GNG E. hepatocyte F. produce acetyl CoA G. enter CAC H. target cells
- glycerol
- 3 FFAs
A. 1 B. 2 C. 2 D. 1 E. 1 F. 2 G. 2 H. 2