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Lipids

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dafofodi's version from 2018-04-07 23:55

Glycerolipids

 

Question Answer
explain this name: 18:1(Δ^9) cis-9-Octadecenoic acid18 carbons long with 1 dbl bond, at position 9 (cis)
what is an omega-3-fatty acid?fatty acid with double bond at carbon 3, counting from the end
what about glycerol is prochiral and what does prochiral mean?C2 is prochiral, meaning it's chiral if the substituents aren't identical)
waxesesters of FAs w/ long-chain alcohols
beeswax formed frompalmitic acid, 1-triacontanol
stearic acid is a ___ FAsaturated
oleic acid is a ___ FAunsaturated
double bonds in unsaturated FAs are (cis/trans)cis
triacylglycerols3 FAs in ester linkage w/ glycerol
triacylglyceride fxstorage
why is the spermaceti organ interesting?it's a mix of waxes and triglycerols with temperature-dependent viscosity, so can affect buoyancy
what are the units of micelles?wedge-shaped individual lipids
what determines the shape of a lipid cluster?shape of individual lipid
storage lipid?triacylglycerols
are triacylglycerols polar?no, they're neutral
membrane lipids?sterols, phospholipids, glycolipids, archaebacterial ether lipids
glycerolipidstriacylglycerols, glycerophospholipids
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Question Answer
glycerophospholipids structuresame structure as triglyceride, but C3 has phosphate group instead
possible head groups of glycerophospholipids-H, -Serine, choline, -CH3-CH2-N+H3, -inositol 4,5-biphosphate, cardiolipin
glyceroglycolipidssame structure as triglyceride, but C3 bound to sugar
ether lipids structureether rather than ester linkage
example of ether lipidplasmalogen, platelet-activating factor
for membranes of Archaea, the ether lipid is a _____ on one end and a _____ on the otherglycolipid, phospholipid (very stiff and high mp)
classes of phospholipasesA1, A2, C, D
phospholipases that cleave at acyl chainA1, A2
phospholipases that cleave at phosphoanhydride bondC, D
phosphatidylinositol pathwayphosphatidyl inositol (phosphorylated twice) --> PIP2 --PLC--> DAG + IP3. DAG activates PKC, IP3 releases intracellular Ca2+, steps that both regulate other enzymes
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Sphingolipids and sterols

 

Question Answer
sphingomyelin has ___ has head group substituent-P-O-Choline
sphingosine structure?HO-C3H-CH=CH-R; C2H-NH-fatty acid; C3H2-O-[head group]
sterols have _________ fused rings and (other distinguishing factor)4; polar head (OH). also many stereocenters
bile acids aredegradation products of cholesterol that have detergent-like properties
cholesterol is precursor to?important steroid hormones - testosterone, estradiol, cortisol, aldosterone
isopreneCH2=C(-Me)-CH=CH2
isoprenoid compoundsfat-soluble vitamins - A, D3, E, K as well as sterols
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Membrane lipids

 

Question Answer
___ movement of phospholipids in membrane is very fastlateral
___ movement of phospholipids in membrane requires ATP input, catalysistransbilayer
membranes in cells are above the transition temperature in a ____ statefluid
how does e coli respond to increasing temperature?increases saturated fatty acid composition in the cell membrane
effect of sterol presence in membraneprevent highly-ordered packing; membrane plasticizers
transition temperaturetemperature at which transition from fluid --> paracrystalline structure occurs in membrane
what is FRAP used for?Fluorescence Recovery After Photobleaching, can measure rate of fluorescence return due to phospholipid diffusion
more unsat. fats = (less/more) fluidmore
as T increases, unsat/sat ratio (increases/decreases)decreases
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Membrane proteins

Question Answer
enzymes that catalyze transbilayer translocationsflippase, floppase, scramblase
integral vs. peripheral membrane proteinsintegral: firmly associated, only removed with detergents, solvents; peripheral: associated by electrostatics or H-bonding, removed with pH changes, mild treatments
membrane helices typically have ___ turns, corresponding to ____ residues6-7 turns, 20-25 residues
what do hydropathy plots tell us?predict membrane-spanning regions of proteins
Tyr and Trp in membrane proteins resideat the water-lipid interface
define passive transport and give examplefacilitate diffusion down electrochemical gradient, ie aquaporins
define primary active transport and give exampleendergonic or "uphill" transport directly couples to exergonic chemical reaction (ATP hydrolyis), example: Na/K ATPase
define secondary active transport and give exampleendergonic or "uphill" transport directly couples to exergonic "downhill" flow of a DIFFERENT solute, example: chloride-bicarbonate exchanger
glucose transport into erythrocytes is an example offacilitated uniport
bicarbonate entering erythrocytes from blood plasma is an example offacilitated antiport (electrical potential does not change)
glucose transport INTO intestinal epithelial cells is an example ofsecondary active transport, symporter driven high extracell. [Na]
what is electrogenic transport?when the solute is an ion and its movement is not accompanied with a counterion
how is concentration determined with electrogenic transport?ΔGt=RTln(C2/C1)+ZFΔ(psi) where Δ(psi) is electrical potential difference, Z is charge of solute
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