Topic 2.4 - Plasma Membranes 𖦹⋆｡°✩ Flashcards
what do cells have that allow them to establish an internal environment
membranes
what do cell membranes do for the cell
༻ provide a boundary between the interior of the cell and the outside environment
༻ control the transport of materials in and out of the cell
phospholipids are amphipathic. what does this mean
they contain both polar (phosphate head) and non polar (fatty acid tail) properties
what phospholipids form
they spontaneously form a bi-layer in an aqueous environment
where are the heads and tails located
༻ tails are located inside the bilayer
༻ heads are exposed to the aqueous outside and aqueous inside environments
what do embedded proteins and phospholipids have in common
they are both amphipathic
what are peripheral proteins
༻ loosely bound to the surface of the membrane
༻ hydrophilic with charged and polar side groups
what are integral proteins
༻ span the membrane
༻ hydrophilic with charged and polar side groups
༻ hydrophobic with nonpolar side groups penetrate hydrophobic interior of bilayer
what is an example of integral proteins
transmembrane proteins
what roles do embedded proteins play in maintaining the internal environment of the cell
༻ transport
༻ cell-cell recognition
༻ enzymatic activity
༻ signal transduction
༻ intercellular joining
༻ attachment for extracellular matrix/cytoskeleton
what is the Fluid Mosaic Model and how is it structured
a mosaic of protein molecules in a fluid bilayer of phospholipids. the structure is not static and is held together primarily by hydrophobic interactions which are weaker than covalent bonds. most lipids and some proteins can shift and flow along the surface of the membrane or across the bilayer
what are the components of the Fluid Mosaic Model?
༻ proteins
༻ steroids
༻ carbohydrates
what is cholesterol
a type of steroid that is randomly distributed and wedged between phospholipids in the cell membrane of eukaryotic cells
what does cholesterol regulate
regulates bilayer fluidity under different environmental conditions
what is the function of carbohydrates and lipids
diversity and location of the carbohydrates and lipids allow them to function as markers
