Biochemistry- Lipids Flashcards
What is the action of lipase?
breaks down ester bonds
What constitutes a triglyceride?
3 fatty acids attached to a glycerol backbone
Lecithin or phosphatidylcholine is found in what substance?
phospholipids
what mineral is important in cell membranes?
phosphorous
What does saturated refer to?
all carbons of a fatty acid are saturated with hydrogens (no double bonds)
double bonds are seen in what kind of fatty acid?
unsaturated
how are lipids transported in the blood?
via lipoproteins
how many carbons are in a short chain fatty acid?
6-10
how many carbons are in a medium chain fatty acid?
12-14
how many carbons are in a long chain fatty acid?
16-20
Animal fat is a good source of what type of fatty acid?
saturated
oleic, linoleic and alpha linolenic acids are examples of what type of fatty acid?
unsaturated
hydrogenation of fatty acids produces what?
trans fatty acids
What are 2 effects of trans fatty acids on the body?
- interfere with essential fatty acid metabolism
2. may be athergenic
what substance emulsifies fatty acid?
bile
How do triglycerides cross the intestinal membrane?
drop 2 fatty acids, cross the membrane and reform intracellularly
Ho do tricglycerides travel in general circulation?
via chylomicrons in the lymphatics and blood
Where does beta oxidation take place?
in the mitochondria of all cells
where does fatty acid synthesis take place?
in the cytosol of all cells
what is the activated form of a fatty acid?
Acyl-CoA
How is Acyl-CoA transported into the mitochondria?
carnitine shuttle- (carnitine palitoyl transferase I, II and the carnitine acyl transferase enzymes)
What coenzyme is needed in the activation of fatty acids into acyl-CoA?
B5 pantothenic acid (acyl CoA synthase)
What coenzymes are needed in the beta-oxidation pathway?
B2 FAD
B3 NAD
What is the rate limiting enzyme in fatty acid synthesis?
Acetyl-CoA carboxylase
What is the intermediate substrate for fatty acid synthesis?
Acetyl-CoA–> AcetoacetylCoA–> Acyl CoA –> FFA
Acetyl CoA carboxylase acts on Acetyl-CoA to form what?
Malonyl CoA
What coenzyme is important for the production of malonylCoA from acetyl CoA?
Biotin
What reducing agent is used in fatty acid synthesis?
NADPH
How does acetyl CoA get out into the cytoplasm for fatty acid synthesis?
citrate leaves the mitochondrion and the action of citrate lyase forms acetyl CoA and oxaloacetate
What hormone promotes fatty acid synthesis?
insulin
What is the end product of de novo fatty acid synthesis?
palmitate
What substance is the activated end product of lipogenesis and will cause feedback inhibition on actyl-CoA carboxylase?
Palmitoyl-CoA
What 3 tissues undergo lipogenesis?
liver, skeletal muscle, cardiac muscle
where does chain elongation take place?
in the mitochondrion and smooth ER
which tissues undergo de novo fatty acid synthesis?
liver and adipose tissue
Where does de novo synthesis take place?
in the cytoplasm
What are the 3 ketone bodies?
Acetoacetate, acetone, betak hydroxybutyrate
Keton production takes place when which substance is low?
oxaloacetate
in what tissue does ketone synthesis take place?
liver
where in the cell does ketone synthesis take place?
mitochondrial matrix
What is the fate of acetone?
usually exhaled
What is the fate of 3-hydroxybutyrate?
gets oxidized into acetoacetate
What 2 tissues can use acetoacetate?
brain, skeletal muscle
What are the 3 essential fatty acids?
linoleic acid
alpha-linolenic acid
arachidonic acid
What is a good source of linoleic acid?
vegetables, nuts, seeds
What is a good source of alpha-linolenic acid?
flaxseeds
what is the name of the enzyme that converts linoleum and alpha linolenic acid into their metabolites?
delta-6 desaturase
Which essential fatty acid is omega-3?
alpha-linolenic
Which essential fatty acid is omega-6?
linoleic acid
Which EFA is a precursor for series 2 eicosanoids?
arachadonic acid
Which EFA is a precursor for series 1 eicosanoids?
linoleic acid
Which EFA is a precursor for series 3 eicosanoids?
alpha-linolenic acid
Linoleum acid turns into what fatty acid?
gamma linolenic acid (GLA)
What are some good sources of GLA?
Evening primrose oil, borage oil, black currant oil
What does alpha-linolenic acid become?
Eicosapentaeinoic acid (EPA)
What is a good source for eicosapentaeinoic acid? (alpha-linolenic acid)
cold water fish oils (EPA)
What is the name of the enzyme that releases arachidonic acid from cell membranes?
phospholipase A2
What is the name of the enzyme that converts arachidonic acid into prostaglandins?
cyclooxygenase (also forms thromboxanes), is susceptible to NSAID inhibition
What is the name of the enzyme that forms leukotrienes from arachidonic acid?
lipoxygenase
What products inhibit phospholipase A2?
corticosteroids
What products inhibit cyclooxyrgenase activity?
Aspirin (NSAIDs)
What hormone promotes the conversion of carbohydrates into triglycerides?
Insulin
What enzyme causes the release of fatty acids from triglycerides?
hormone sensitive lipase
What are free fatty acids usually bound to?
albumin
What hormone inhibits that action of hormone sensitive lipase?
insulin
What promotes hormone sensitive lipase?
growth hormone, glucagon, epinephrine
Esterification is used in the formation of TCGs from what two substances?
Acyl CoA and Glucose-6-Phosphate
Free fatty acids are mobilized from what cell?
adipocyte
What apoprotein marks HDL for hepatic uptake?
Apo A1, (and Apo E, but that is primarily for chylomicrons)
What carries dietary fat in the body?
Chylomicrons
Which tissues synthesize chylomicrons?
mucosal cells of the small intestine
Apoprotein A is found on what lipoprotein?
HDL
Which lipoprotein functions to carry TCGs from the liver to extra hepatic tissues?
VLDL
Which lipoprotein functions to carry cholesterol from the liver to extra hepatic tissues?
LDL
Which apoprotein allows for uptake of cholesterol by cells?
Apo B
Chyloremnants are formed from the action of which enzyme?
Lecithin acyl transferase
What apoprotein activates lecithin acyl transferase?
Apo A (HDL)
Which transfer protein facilitates transfer of cholesterol from LDL and VDL to HDL?
cholesterol transfer protein