(L5) Lipid Metabolism Flashcards
What is the major source for fatty acid synthesis?
L5 S6 LO1
Dietary carbohydrates
In what tissues do fatty acid synthesis occur?
L5 S7 LO1
- liver (primary)
- adipose tissue
- brain
- kidney
- lactating mammary glands
What is the precursor of fatty acid synthesis?
L5 S8 LO1
Acetyl-CoA
What are the major steps of fatty acid synthesis?
L5 S9 LO1
- movement of mitochondrial acetyl CoA to the cytoplasm
- generation of malonyl CoA (carboxylation)
- fatty acid chain formation
What steps are involved in transport of mitochondrial acetyl CoA to the cytoplasm?
L5 S12-13 LO1
- condensation with oxaloacetate to for citrate (via citrate synthase)
- transport of citrate from mitochondria
- conversion back to acetyl CoA (via ATP citrate lyase)
- oxaloacetate reduce to malate (via malate dehydrogenase)
- oxaloacetate transported back into the mitochondria via malate-α ketoglutarate transporter and oxidized back to oxaloacetate (via malate dehydrogenase)
- *or**
- malate converted to pyruvate in cytoplasm (via malic enzyme) then transported into mitochondria
What are the regulators of citrate lyase?
L5 S11 LO2
Activators:
- glucose
- insulin
Inhibitors:
- PUFA
- leptin
What is the function of acetyl CoA carboxylase?
What special features does it have?
L5 S15 LO1
Carboxylates acetyl CoA using CO2 to form malonyl CoA.
Uses ATP for bond energy.
Uses biotin as cofactor.
**rate limiting step
What are the regulators of acetyl CoA carboxylase?
L5 S14 LO2
Activators:
- citrate
- insulin
Inhibitors:
- glucagon
- epinephrine
- AMP
- palmitate
- PUFA
What are the regulator of the fatty acid synthase complex?
L5 S17 LO2
Activators:
- insulin
- glucocorticoid hormones
Inhibitors:
-PUFA
What is the function of fatty acid synthase complex?
What special features does it have?
L5 S19;21 LO1
In seven reactions it takes 7 malonyl CoA, 1 acetyl CoA, and 14 NADPH to form palmitate (16C).
Complex formed of two identical dimers that have 7 catalytic activities and an acyl carrier protein (ACP).
What is the total equation for the reactions catalyze by fatty acid synthase?
L5 S21 LO1
Reactants:
- 1 acetyl CoA
- 7 malonyl CoA
- 14 NADPH
- 14 H+
Products:
- palmitate
- 14 NADP+
- 8 CoA
- 6 H2O
What are the reactions catalyzed by fatty acid synthase?
L5 S22 LO1
- condensation
- reduction
- dehydration
- reduction
What are the main sources of NAPDH?
L5 S23 LO1
- pentose phosphate pathway
- malic enzyme
How and where are fatty acids longer than palmitate (C16) generated?
L5 S32 LO3
Location:
- smooth ER (uses malonyl CoA)
- mitochondria (uses acetyl CoA)
Synthesized by addition of 2 carbon groups.
NADPH used as reducing agent.
How and where are unsaturated fatty acids generated or obtained from?
L5 S33 LO3
Catalyzed by acyl CoA desaturases in the SER
4 variaties of desaturaes:
- Δ4 (between carbon 4-5)
- Δ5 (between carbon 5-6)
- Δ6 (between carbon 6-7)
- Δ9 (between carbon 9-10)
Use NADH/NADPH as reducing agent
Fatty acids with double bonds beyond carbon 9-10 (omega 3 and 6 FAs) cannot be synthesized by humans and must be ingested
