15 Lipid Synthesis and Storage Flashcards
What is the primary end product of fatty acid synthesis
Palmitic acid(palmitate) C 16:0
Name 6 essential lipids for human body
Linoleic acid, Linolenic acid, 4 soluble vitamins
How many carbon and double bands do Linolenic acid have
which carbons contain double bands
ω-6 family
18:2 ∆9,12
How many carbon and double bands do Linoleic acid have
which carbons contain double bands
ω-3
18:2 ∆9,12,15
How many carbon and double bands do Arachidonic acid have and what is its precursor
which carbons contain double bands
what can be produced from it
20:4 ∆5,8,11,14
formed from Linoleic acid> it’s precursor for prostaglandins, thromboxanes & leukotrienes
what is the difference between Cis and Trans fatty acids
name some substances that contain Trans acids
Cis- :normal double bound configuration > lots of free space in molecule > it’s liquid
Trans- :unnatural and predominate in margarine & partial hydrogenation of vegetable oils
what’s the similarities between saturated and trans FAs
Saturated FAs & Trans- FAs have same structures & are solid at cool temperatures > ↓membrane fluidity > won’t let LDL inside the cells > ↑ risk of atherosclerosis
What are the positive effects of omega 3 FAs
what can it be found in
↓risk of cardiovascular disease: replace some arachidonic acids in platelet membrane thus ↓ Production of thromboxane & platelets to aggregate
Also ↓ serum Triglycerides
Omega-3 found in cold-water fish: Salmon, Tuna & herring as in some nuts(walnuts) & Seeds(flax seeds)
How is a FA activated
During metabolism > they are first activated by attaching coenzyme A (CoA)
fatty acyl CoA synthetase catalyzes this activation step
Fatty acid + CoA + ATP ~ Fatty acyl CoA + AMP + PPi
How much is the maximum recommended daily need for TGs
80 grams of TGs
What is Atkin diet
high lipid & low carbohydrate containing diet
Which enzymes have an effect on lipids inside intestinal lumen
what are their results
Bile, Lipase, Colipase, Cholesterol esterase
Result: 2FAs, 2-monoglyceride & Cholesterol
packaged with apoprotein B-48 in chylomycrons
What is Colipase
binds lipase>shift optimum pH to 6 & protect it from bile
What does Steatorrhea mean
what are its causes, and which particle will be lost in each cause
> 6% fat in stool
Exclusion of bile: TG
Exclusion of pancreatic juice: TG
Malabsorption: FA
Insulin effects on conversion of glucose to acetyl coA and FA synthesis
during glycolysis: Glucokinase(induced), PFK-2(dephosphorylated), PDH(dephosphorylated)
Insulin effects on FA:
Acetyl CoA carboxylase(dephosphorylated, Activated)
FA synthase(induced)
Ingredients for FA synthesis
and where does this happen
AcCoA(Citrate shunt), NADPH(1HMP shunt, 2Malic Enzyme), CO2, ATP(from Krebs)
FA synthesis happens in Cytoplasm
Explain the 1st part of FA synthesis from glucose inside mitochondria
Pyruvate by PDH to acetylCoA then to Citrate
or Pyruvate by pyruvate carboxylase(+Biotin) to OAA then to Citrate
Citrate shuttle send it to cytoplasm
What happens to Citrate in FA synthesis after citrate shuttle outside mitochondria
Citrate by Citrate lyase produce Acetyl CoA and OAA
OAA: to Malate then by Malic enzyme to Pyruvate: Produce NADPH needed for FA synthase(also from HMP)
Pyruvate goes back to mitochondria
Explain the 2nd part of FA synthesis from acetyl CoA
AcCoA by AcCoA carboxylase with help of ATP, Biotin, CO2(ABD) to malonyl CoA
Activated(dephosphorylated) by insulin and Citrate
But inhibited by glucagon
Malonyl CoA by FA synthase and help of NADPH and pantothenic acid, release that CO2 and produce FA(palmitate)
Induced by Insulin
what can be done to the product of FA synthase (palmitate)
Fatty acyl CoA may be elongated and desaturated (to a limited extent in humans) using enzymes associated with the smooth endoplasmic reticulum (SER):
Cytochrome b5 is involved in desaturation reaction
What is the utility of Malic Enzyme in FA synthesis cycle
Additional source of NADPH in liver & adipocytes + HMP shunt
What does Acetyl CoA carboxylase require to produce Malonyl CoA
Rate-limiting enzyme, require ATP, Biotin, CO2 (ABC carboxylase)
What does Control Acetyl CoA carboxylase
Activated by insulin(dephosphorylated) & Citrate
What does FA synthase require to produce FAs
Contains acyl carrier protein(ACP), requires vitamin pantothenic acid, need NADPH
What does Control FA synthase
It is induced by insulin in liver
What is the effect of Ethanol on fat production in liver
Ethanol disrupts VLDL synthesis> result in fatty liver
why linoleic & linolenic are essential
Humans cannot desaturase beyond C-9 in FA chain
