Flashcards in Overview of Lipid Biochemistry Deck (24):
Fatty acids are categorized as either ____________.
saturated or unsaturated
What is triglycerol?
A three-carbon chain with hydroxyl groups on each carbon.
Explain how fatty acids are a part of triglycerides – which can be put into gluconeogenesis – but cannot serve as substrates for gluconeogenesis.
The triglyceride carbons that go into gluconeogenesis come from the triacylglycerol backbone, not the fatty acid chains that get esterified to triacylglycerol to form triglycerides.
Describe the overall structure of phospholipids.
Phospholipids are based on the structure of triglycerides: there are two hydrocarbon chains esterified to a glycerol backbone, but the third carbon is replaced by a phosphate group.
Which kinds of lipids are the most polar? The least?
Free fatty acids
Triglycerides and cholesterol esters
What phospholipid ratio is tested for evaluation of fetal lung disease?
Phosphatidylcholine (a type of lecithin) : sphingomyelin ratio greater than 2 indicates lung maturity
Describe the synthesis of fatty acids and note the regulated step.
(Acetyl co-a carboxylase) ***REGULATED STEP***
(Fatty acid synthase – two-carbon transfers of acetyl co-a on to malonyl co-a and the subsequent growing fatty acid)
Lipoprotein lipase does what ____________.
moves triglycerides from the blood to the adipose tissue
VLDL serves what purpose?
It delivers fat from the liver to adipose tissue.
Acetyl co-a carboxylase is stimulated by ___________.
Triglycerides are moved out of adipocytes by ______________.
When fatty acids move into liver or muscle cells, they bond with ____________.
acyl, for fatty acyl co-a
What is the regulated step in lipolysis?
Carnitine palmitoyl transferase (which pumps acyl into mitochondria)
True or false: free fatty acids are complexed to proteins in transport.
Ketones are made from ____________ by the enzyme _______________.
acetyl co-a; HMG co-a synthase
Trace the cholesterol-synthesis pathway and list the regulated steps.
(HMG co-a synthase)
HMG co-a (hydroxymethyl glutaryl co-a)
(HMG co-a reductase) ***REGULATED STEP; USES NADPH***
What are the five major groups of lipids?
Free fatty acids
VLDL is ________________.
triglycerides packed with proteins circulating in the blood
When glucagon is high and insulin low, triglycerides in adipose tissue are broken down by ______________.
Lipase breaks down triglycerides to triacylglycerol and free fatty acids that ______________. After getting there, what happens?
circulate to the liver; they must be converted to acetyl carnitines that get pumped into the mitochondria of hepatocytes by carnitine palmitoyl transferase 1 (which is the rate-limiting step in fat oxidation)
In the mitochondria of hepatocytes, fatty acids get _______________.
broken down in two-carbon fragments (beta oxidation) that enter the TCA cycle as acetyl co-a
The rate-limiting step in ketogenesis is _____________.
synthesis of Hmg Co-a
Sphingolipids have a ____________ backbone.
ceramide (nitrogen-containing because it is derived from serine)