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37 Cards in this Set
- Front
- Back
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Triglycerides are the major what? Where are they stored?
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storage form of lipids
adipose, muscle, liver, skin |
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What is the solubility of TG?
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slightly polar, low solubility
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How are structured triglycerides produced?
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by mixing MCFA and Long chain TG
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What can structured triglycerides be used for?
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in infant formulas to make TG with one LCFA at sn-2 and 2 MCFA at sn-1 and sn-3. Leaves LCFA at sn-2 which is important for brain and neuro development
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What does pancreatic lipase prefer?
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Short-chain and Medium-chain over Long-chain. Unsaturated preferred over saturated.
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LCFA in sn-2 position are absorbed as ______
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2-MG
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Why does stearic acid have a cholesterol neutral effect?
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transformed to MUFA
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Phospholipid structure:
sn-1 = sn-2 = sn-3 = |
sn-1 = FA
sn-2 = FA sn-3 = Phosphate (may be free or esterfied) |
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What is the phospholipid role in cell signaling in response to a hormone?
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Hormone binds to receptor > G-Protein > Phospholipase C > IP3 calcium eflux from ER > Ca activates enzymes that decrease glycogen systhesis
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Steroid structure?
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perhydro-1,2, cyclopentano-phenanthrene ring system
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What is the solubility of steroids?
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polar and insoluble. (interior is nonpolar)
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What do steroids modulate?
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membrane fluidity
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Digestion of fat begins in the stomach with enzyme ____ which has optimal activity at pH _. It hydrolyzes FA at sn-_ position and also at sn-_, but not as efficiently
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Gastric Lipase
4 sn-3 sn-1 |
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Gastic lipase efficiently digests ____. It does not hydrolyze FA attached to ___ or ___.
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milk fat
phospholipid or cholesterol |
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What % efficiency is gastric lipase?
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10%
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Bile salt (intestine)
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hydrophobic and hydrophilic end - fat becomes droplet size
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Pacreatic lipase
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acts on sn-1 and sn-3 position; greater affinity for SCFA and MCFA. Secretin to optimize pH 7.5-8. CCK stimulates gallbladder contraction to release pancreatic lipase
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Pancreatic lipase related protein-2
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braod activity- hydrolyzes TG, PL, others. does not need co-lipase
*important to TG digestion in newborn when secretion is high *as pancreas matures, produce less of Related Protein-2 |
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Co-lipase
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binds to droplet for optimal positioning of pancreatic lipase
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phospholipase A2
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secreted from the pancreas; specific for FA at sn-2 position
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What is the substrate of phospholipase A2?
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PL in mixed micelles
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10-15% of dietary cholesterol is in the form of ______.
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cholesterol ester
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Carboxyester lipase
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cleaves FA from cholesterol
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Carboxyester lipase secreted from the ____ has broad specificity; ____
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pancreas
sn-2 |
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What is the function of a mixed micelle?
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transports LCFA through aqueous environment (unstirred water layer) to the brush border. One cell thick. [Also chol and PL]
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What kind of absorption in lipid digestion?
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Passive diffusion & Carrier-mediated uptake of some FA's and Carrier-mediated uptake of Chol
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CD36 fatty acid translocase
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translocates LCFA across apical membrane of enterocyte
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Niemann-Pick C1 like 1 protein
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moves cholesterol from apical surface to intracellular compartment of enterocyte
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Uptake of cholesterol requires _____, and may involve ___ and _____
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Niemann-Pick C1 like 1 protein
CD36 and SR-B1 |
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Only _% of the cholesterol we eat is absorbed. Why?
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50%
through ATP-binding cassette protein (ABCG5 and ABCG8) on apical membrane remove cholesterol for N-pick and put it back in the lumen; not absorbed efficiently. Transport plant sterols out of enterocyte: ~1% absorbed |
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Mutations in ABCG5 and ABCG8 cause condition _______.
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beta-sitosterolemia
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Plant sterols as functional foods displace ___ from mixed-micelle
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cholesterol
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Re-esterification of TG in ER can occur in which two pathways?
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Monoacylglycerol Pathway and Glycerol 3-Phosphate Pathway
*NOT for SCFA and MCFA |
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Re-esterification of TG in ER is induced by what?
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insulin
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What happens after re-esterification of TG?
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TG packaged into chylomicron to be secreted into the lymph
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Re-esterification of phospholipids in ER
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Reesterfied with activated FA through the action of lysophospholipid acyltransferase
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Re-esterification of cholesterol in the ER
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CL reesterfied with activated FA through action of ACAT and cholesterol esterase
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