2.08 Membranes and Transport System Flashcards
Vesicles surrounded by a lipid bilayer with an aqueous interior
Liposomes
Tested as red cell substitute, to deliver encapsulated drugs and as vectors for gene therapy
Liposomes
Membranes lipids are composed of _______
Phospholipid
Glycolipid
Cholesterol
2 types of membrane proteins
Integral protein
Peripheral protein
Permanently bound, fixed in the membrane
Integral protein
Do not penetrate the hydrophobic layer of membrane
Peripheral protein
___ are asymmetrically distributed in the membranes
Lipids
ATP-dependent lipid class of transporters specific for phosphatidylserine and phosphatidylethanolamine
Flippase
Outward directed ATP-dependent transporter; non-specific for phospholipid
Floppase
Most membrane lipid and protein can freely move through the membrane plane
Lateral mobility
Fluidity of membrane depends on ____ and ___
Temperature
Lipid composition
Temperature at which membrane starts to become fluid from gel-like consistency
Transition temperature
Interactions between hydrophobic tails ____ fluidity
Decrease
Increase in fluidity , ___ in permeability to water and other small hydrophilic molecules
Increase
Membrane allows adjustments of cell compositions and functions
Selectivity
Steroid, amphipathic, found in animal cells, found in both leaflets of bilayer
Cholesterol
Major lipid component of cell membrane, amphipathic, phosphatidylcholine, sphingomyelin
Phospholipid
Cholesterol (increases/decreases) fluidity if the temperature is below the transition temperature
Increases
It interferes with the interaction of hydrocarbon fails of fatty acids
As the fluidity increases, the permeability to water and other small hydrophilic molecules ______
Increases
As the concentration of unsaturated fatty acids in the membrane increases, fluidity _____
Increases
Cholesterol (increases/decreases) fluidity if the temperature is above the transition temperature
Decreases
It limits the disorder because cholesterol is more rigid than the hydrocarbon tails of the fatty acids
Contains choline head group and glycerophosphoric acid
Precursor of sphingomyelin
Phosphatidylcholine
Contains predominantly the longer chain fatty acids, with carbon length of 24
Serves in signal transduction and insulation of nerve fibers
Sphingomyelin
Least common of the membrane lipids
Always found on the leaflet membrane
Glycolipid
Involved in the cell identity
Glycolipid
Penetrate bilayer or span membrane
Integral protein
2 types of integral protein
Transmembrane protein
Covalently tethered integral protein
Single pass or multiple pass
Transmembrane protein
Integral proteins are synthesized in ____
RER
Functions of integral proteins
Enzymatic Receptor Transport Communication Adhesion
Proteins that do not penetrate the whole membrane
Not covalently linked to other membrane compounds
Peripheral proteins
Peripheral proteins are synthesized in ____ and ____
Cytoplasm (cytoplasmic-inner- side)
ER and exocytosed (extracellular-outer-side)
____ play a role in cell-to-cell recognition
Membrane carbohydrates (oligosaccharides)
Specialized region in the membrane that play a role in signaling
Composed of cholesterol and sphingomyelin
Lipid rafts
Little caves
Groups of integral protein that contain caveolin
Transcellular pathway or signaling process
Caveolae
Intercellular juction that serves as barrier to prevent the molecules and ions to move freely between cells
Tight junctions
Constitutive, regulated
Exocytosis
Preferably at clathrin coated pits
Endocytosis
Processes involved in the cell membrane
Exocytosis
Endocytosis
Phagocytosis/pinocytosis
Small solute movement
Allow direct flow of molecules from one cell to another
Gap junction
Movement across biological membrane, does not require energy
passive diffusion