Lecture 1 Flashcards
1
Q
cell membrane and function
A
- fluid mosaics of lipids and proteins
- selectively permeable
- passive transport
- active transmort
- bulk transport
2
Q
membrane
A
- plasma membrane is boundary separating living cell from surroundings
- thin and fluid
- formation of membranes must be early in evolution
3
Q
structure
A
- fluid mosaic (phospholipids with ‘mosaic’ of proteins embedded
4
Q
phospholipids
A
- most abundant lipid in plasma membrane
- containe hydrophobic and hydrophilic regions
- Choline; phosphate; glycerol; fatty acid
- amphipathic nature = formation of bilayer in water
5
Q
fluidity of membranes
A
- lipid membrane must be fluid in order to flunction
- phospholipids in plasma membrane can move within bilayer
- temp. cools, membrane switch from fluid to solid state
- membrane rich unsaturated fatty acids more fluid than rich saturated
- plants can adjust membrane composition with season
6
Q
membrane proteins and their functions
A
- proteins embedded in lipid bilayer determine = most of membrane’s specific function
- 6 major functions: Transport; enzymes; signal transduction; cell-cell recognition; intercellular joining
- attatchment to sytoskeleton and extracellular matric (ECM)
7
Q
membrane structure results in selective permiability
A
- cell must exchange materials with surrounding, process controlled by the plasma membrane
- plasma membranes selectively permeable
- affect permeability: lipid bilayer; transport proteins
8
Q
permeability of lipid bilayer
A
- hydrophobic molecules (nonpolar) can pass through lipid bilayer rapidly (O2; CO2)
- hydrophilic molecules (ions and polar) do not cross easily (sugar; water; Na+; K+)
9
Q
transport proteins
A
- allow passage of hydrophilic substances across membrane
- two main types: channel proteins; carrier proteins
- channel: hydrophilic channel that certain molecules/ion can use as tunnel (aquaporins)
- carrier proteins: bind to molecule and change shape to shuttle across membrane (glucose uptake faster)
