Membrane structure and function Flashcards
lipids components
- phosphogylcerides *
- sphingolipids
- sterols
Proteins components
- peripheral (membrane interacting)
- integral (through membrane)
Carbohydrates components
-mono, di, oligo (glyco- protein and lipids)
Selective permability
intrinsic phospolipids
energy transduction
- inner mitochondrial membrane- ETC
- chloroplast thylakoid- Photosynthesis
- bacterial plasma membrane
transport
proteins transport
aquaporins
H2O transport
communication
single transduction (hormones) and cell-cell recognition (gylcoprotein identification) -enyzme activity faciliate intercellular joining
E-face
exoplasmic
-outside facing
P-face
protoplasmic
-inside facing
phospholipids
-can move lateral, rotatate, flex FA chain, and flip flop (enzyme called flipases)
Membrane proteins
move slowly but not laterally (diffuse slowly)
membrane must be fluid
too fluid= loss of organization and support
too rigid= poor motility
Factors effects membrane fluidity
- less fluid; low temp, longer FA chain, trans double bonds
- more fluid= high temp, shorter FA chain, cis double bonds
- cholesterol= decrease fluidity at high temps and increase at low temps
Phosphlipid bilayer
-selective permeable (water can cross) and transport proteins allow additional discrimination
hydrophobic molecules
free diffusion
small uncharged polar molecules
some resistance, transport protein helps
large uncharged polar molecules
large resistance, transport protein required
inorganic ions
large resistance, transport protein required
Passive transport
diffusion of substances across membrane with no energy investment
diffusion
substance moves from high concentration to low via thermal motion
concentration gradient
difference in solute concentration across membrane or between two parts
Osomsis
simple diffusion of free water across a selectively permeable membrane
molarity
concentration of solute (pressure)
osmolarity
concentration of solvent (pressure)
osmotic pressure
solution to take up water when separated from pure water by semipermeable membrane Higher osM=higher concentration of solvent
tonicity
ability of a solution to cause a cell to gain or lose water
solute concentration
isomotic vs isotonic
- same osmotic pressure as other fluid
- some solute concentration of solute
hyperosmotic vs hypertonic
- same higher osmotic pressure then other fluid
- fluid with greater concentration of solute
hypoosmotic vs hypotonic
- lower osmotic pressure then other fluid
- fluid with lower concentration of solute
Faciliate diffusion
- channel protein= hydrophilic channels allow ions past
- carrier protein= shape changes which takes ions across
- No ATP needed
Active transport
-moves substance across membrane, through transport protein against a chemical gradient (requires energy)
active transport energy sources
- ATP hydrolysis
- light absorbance
- e- transport (cotransport with something moving down its gradient)
Exocytosis
removal of extracellular fluid (out)
constitutive exocytosis
continuous, supplies proteins and lipids to plasma membrane and secretes molecules from cell
regulated exocytosis
operates in secretory cells, membrane fusion occurs only in response to extracellular signal
Endocytosis
uptake of molecules to extracellular fluid (taken in)
Phagocytosis
uptake of large bulky material (feeding and defence)
-microfilaments/myosin cause engulphment and then pinching off into cell
pinocytosis
ingestion of liquid into cell by budding membrane
receptor mediated endocytosis
specific molecules are taken up form extracellular fluid, mediated by cell membrane and cytosolic proteins
-forms coated vesicles
