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how can lipids be extracted
with organic solvents
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role of lipids in cell
- storage-good source of energy; fat
- structure-membrane
- pigments-light absorbs
- biological signals-fat soluble vitamins, hormones
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important naming convention for lipids
- start at the carbon on the carboxylic carbon
- Δ where the double bond is and number
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the more double bonds a fatty acid has...
the lower the melting temp and the more double bonds it has
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know what triaglycerols/rides and glycerophospholipids look like
sure
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role of phospholipases in lipid analysis
- degrades cellular membranes, decreases blood pressure, prevents coagulation
- in the venom of snakes
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be familiar with the 4 ring steroid nucleus
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Membrane compostition
- contains lipids, sterols, and proteins
- membrane composition is associated with its function
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micelles
spheres of dozens to thousands of lipid molecules
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lipid vesicle
- small bilayer with central aqueous cavity that carry molecules
- fuse readily w/ cell membranes or w/ each other
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types and rates of lipid diffusion
- lateral-fast
- transeverse-moving from one layer to the other
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integral proteins
membrane proteins embedded in the lipid bilayer
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peripheral proteins
- protein associated w/ integral membrane proteins
- not embedded in the LB
- can be easily dissociated from the integral proteins
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amphitropic proteins
- found in the cytosol and membrane
- linked to membrane during regulatory events
- relies on the attachment of lipids on the membrane
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role of sds in protein denaturation/membrane protein isolation
- helps integral proteins to remain soluble
- sodium dodecyl sulfate
- applies a negative charge to protein to denature them
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amino acids that may be in the membrane
glycine (Gly), alanine (Ala), valine (Val), leucine (Leu), isoleucine (Ile), proline (Pro), phenylalanine (Phe), methionine (Met), and tryptophan (Trp)
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7 transmembrane segment a-helix motif
structure of the G Protein- coupled receptors
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GPCRs
- G-coupled protein receptors
- imbedded protein that acts as a coupler for g proteins
- ligand induces conformation change to make it active
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membrane anchors
- palmitoylation
- myristoylation
- farnesyation
- geranylgeranylation
- another one
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properties of phase separation
- nucleolus separated by phase
- RNA cell signaling molecules dictate phase
- phase separation depends on Protein properties
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flippase
moves lipid from outer to cytosolic leaflet
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bacteriorhodopsin
a 7-transmembrane segment protein
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uncatalyzed membrane transport
- non-specific, non saturable kinetics
- passive diffusion-ion channels
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catalyzed membrane transport
- specific, saturable kinetics
- facilitated diffusion-passive transporters
- active transporters-atp and gradient driven
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role of permeases
- increase rate
- facilitated diffusion
- creates hydrophilic environment for glucose
- enzyme-like (lowers energetic barrier)
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hyperbolic equation for transport rxn kinetics
V0 =Vmax[S]out/ (Kt + [S] out)
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relationship between concentration gradients and G
- ΔG=RTln(C2/C1)+ZFΔψ
- Z=Charge
- F=faradya constant(96.5)
- R=8.314
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SERCA
- Sarcoplasmic/Endoplasmic reticulum Ca pump
- ATP provideds energy for active transport of Ca
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uniport, symport, antiport
- uni-1 substrate moves
- sym-two substrates move at one time
- anti- 2 substrates move through in opp. directions at one time
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features of ion channels
- hydrophilic pores
- ion selective
- sometimes gated
- not 'saturable'
- diffusion limited
- single gate
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