New Material for Final Exam Flashcards
Saturated Fatty Acids
no double bonds in their carbon chain
Unsaturated Fatty Acids
contain cis double bonds, which are arranged so that there is no conjugation
Tm
increases with additional CH2 groups and counteracted by presence of CIS double bonds
Myristic Acid
14:0 CH3(CH2)12COOH, know how to draw structure
Palmitic Acid
16:0 CH3(CH2)14COOH, know how to draw structure
Stearic Acid
18:0 CH3(CH2)16COOH, know how to draw structure
Palmitoleic Acid
16:1 (Delta 9), know how to draw structure
Oleic Acid
18:1 (Delta 9), know how to draw structure
Linoleic Acid
18:2 (delta 9,12), know how to draw structure
Triacylglycerols
Made up of 3 fatty acids linked to glycerol by an ester bond
Stored in adipose tissue to provide: energy storage, insulation, and cushioning
Glycerophospholipids
Similar to triacylglycerols but has phosphate instead of one fatty acid
Could be linked to another molecule that contains a hydroxyl that includes CHOLINE or ETHANOLAMINE, SERINE, INOSITOL, or GLYCEROL (linked to another phospholipid)
Phospholipids
amphipathic and this form membrane bilayers
Sphingolipids
derived from sphingosine, linked to another fatty acid by an amide bond known as ceramide, end hydroxyl group of a ceramide may be linked to a head group
Cholesterol
Rigid semi-planarity, weakly amphipathic, precursor of steroid hormones, critical component of membranes
Groups of Lipids
amphipathic and this self-associate into micelles and bilayers (membranes). When bilayers form spheres, these are vesicles
Individual lipids in a membrane:
rapidly laterally mobile, almost never swap sides, confused by interactions between polar head groups
Lipids change sizes due to
flippases, flippases, and scramblases
Asymmetric
two sides inner and outer leaflets of a membrane
Liquid-ordered
below the transition temperature, membrane forms a sort of rigid gel, disrupts “gel” formation below transition temperature
Liquid-disordered
above the transition temperature, membrane is much more fluid
Lipid rafts
dense microdomains made up of cholesterol, glycosphingolipids and associated proteins
Membrane proteins
remain (partially) solvent accessible, interact with the membrane with specific directionality
Peripheral membrane proteins
weak association with polar head groups
Amphitropic proteins
spend time both on and off the membrane
Integral membrane proteins
traverse the membrane (usually exposed to both sides), hydrophobic residues are exposed to the membrane interior, loops are absent from the protein interior, positive charges are more common on the cytoplasmic side, Tyr, and Trp often sit at the interface between lipid and aqueous phases
Examples: K+ channel, maltoporin, outer membrane phospholipase A, OmpX, and phosphoporin E
Fatty Acylation
found on cell interior
Prenylation
found on cell interior
Glycophosphatidylinositol
found on exterior proteins
Equilibrium
concentrations are equal on both sides of the membrane
Active transport
requires energetic coupling
Passive transport
does not require energetic coupling
Moving molecules through a membrane is difficult:
some (nonpolar) molecules pass through a membrae by simple diffusion, but it is essentially impossible for polar molecules to do so
Ionophores (carrier molecules)
take ions down a gradient, unfavorable: against gradient not useful, favorable: useful
Channels (porins)
down electrochemical gradient; may be gated by a ligand or ion
Transporters (permeases)
against electrochemical gradient, driven by ion moving down its gradient, only open to one side of a membrane at a time, usually follow Michaelis-Menten equation (w/ Vmax & Kt, etc.)
Aquaporin
allows water in at incredibly fast rate, prevents H+ from entering cell and disrupting electrochemical gradients
Repels H3O+ with positively charged R narrowest part of channel
prevents proton hopping by positioning H-bonding Ns (of NRA sequence) too far apart to allow H-bonding between water molecules
Symport
ions go same direction, ions go out of cell, favorable
Antiport
ions go opposite direction, switch signs, unfavorable
Active Transport
moves particles up a gradient by using the free energy released by another process
Primary active transport
transporter itself generates this energy, usually by ATP hydrolysis
Secondary active transport
another transporter generates the energy by creating another gradient
SERCA Pumps
uses ATP hydrolysis to push 2 Ca2+ out of the cell
5 domains: 2 transmembrane domains (T,S) and 3 cytosilic domains (N,P,A)
