L23- Intro to Lipid Metabolism Flashcards
(36 cards)
Carbons in fatty acids are numbered from the _____ (functional group) carbon towards the terminal _____ (functional group) carbon.
Carboxyl, methyl.
Where is the beta carbon positioned on a fatty acid chain?
The beta carbon is the 3rd carbon from the carboxyl end.
Where is the omega carbon positioned on a fatty acid chain?
The omega carbon is the terminal methyl carbon of the fatty acid chain.
What is the difference between unsaturated and saturated fatty acids?
Unsaturated fatty acids contain at least one carbon-carbon double bond, whereas saturated fatty acids contain only single bonds between carbons.
Name the essential fatty acids for humans.
Linoleic acid and alpha-linoleic acid.
What is the omega number of a fatty acid?
It is the number of carbons from the terminal methyl carbon to the nearest double bond.
What is the effect of increasing chain length on the water solubility of fatty acid salts?
The solubility decreases.
What is the effect of increasing chain length on the melting point of uncharged saturated fatty acids?
The melting point increases.
In general, the addition of two carbons to the tail of a saturated fatty acid increases melting point by how many degrees?
10 degrees Celsius.
What the effect of introducing double bonds on the melting point of fatty acids?
The introduction of double bonds decreases the melting point of fatty acids, with trans-double bonds having a greater effect than cis-double bonds.
Describe the structure of a triacylglycerol (TAG) molecule.
TAGs consist of three fatty acids, each linked to an OH group on glycerol in an ester bond.
What is the major form of storage lipid in cells?
Triacylglycerols (TAGs).
Which organ stores and releases bile salts?
The gallbladder.
What process breaks down and solubilizes dietary fat in the small intestine?
Emulsification.
What is the major function of bile salts in the small intestine?
They act as an emulsifier by coating the surface of fat droplets, thereby solubilizing the fat droplets in water.
Which enzyme catalyzes the hydrolytic cleavage of TAGs in the small intestine?
Pancreatic lipase.
Pancreatic lipase hydrolyzes TAGs into what products?
Pancreatic lipase cleaves TAG ester bonds in the 1 and 3 position, producing two fatty acids and one 2-monoacylglycerol (2-MAG) molecule.
What are two conditions that can cause steatorrhea?
Biliary obstruction and pancreatic diseases that diminish the synthesis of pancreatic lipase.
Why is it advantageous for fatty acids to be resynthesized into TAGs in intestinal mucosal cells?
It keeps the free fatty acid concentration in intestinal mucosal cells lower than the concentration in the lumen, allowing for the continued absorption of free acid acids.
Which enzymes catalyze the activation of fatty acids to form fatty acyl-CoA derivatives in intestinal mucosal cells?
Fatty acyl CoA synthetase (also called thiokinase) and inorganic pyrophosphatase.
Fatty acyl CoA synthetase catalyzes the formation of what kind of bond between fatty acids and coenzyme A?
Thioester bond.
What two sequential reactions are catalyzed by fatty acyl CoA synthetase?
The first reaction is the hydrolysis of ATP to generate inorganic pyrophosphate (PPi) and fatty acyl-AMP. The second reaction is the displacement of AMP by coenzyme A to generate an acyl-CoA.
What is the approximate Gibbs free energy of the reaction catalyzed by fatty acyl CoA synthetase?
Zero.
What drives the reaction catalyzed by fatty acyl CoA synthetase in the forward direction (towards the production of acyl-CoA)?
The cleavage of PPi into 2 Pi by inorganic pyrophosphatase.
