Membranes Flashcards
function of a membrane
separation of the content of the cell from the outside
and the separation of the individual organelles and the cytosol
compartmentalisation
formation of separate membrane-bound areas in a cell
why is compartmentalisation important to the cell
metabolism contains incompatible reactions & the specific chemical conditions like pH, etc. can be provided
how can you distinguish membranes that enclose cells from membranes of the organelles? (by name)
cell membrane is called cell-surface/ plasma mebrane
structure of a membrane
phospholipid bilayer
types of proteins in the cell-surface membrane
intrinsic and extrnsic
intrinsic proteins
embedded through both layers of the membrane
channel proteins
hydrophilic channel
–> passiv transport of ions and polar molecules
carrier proteins
passiv and active transport through membrane
passive transport
along a gradient
aktive transport
against a gradient
extrinsic proteins
present in one side of the bilayer
why does temperature affect the cell membrane structure?
phospholipids move continuously –> increased temperature –> increased kinetic energy
do cell membranes denature?
no they are destroyed or disrupted
what influences the structure of cell membranes?
- temperature
- solvents
why can alcohol be used as an disinfectant?
it destroys the cell membrane of the bacteria
why are there changes in the behavior of people who drank alcohol?
the alcohol disrupted the neuronal membranes and nerve impulses are no longer transmitted as normal
does passive transport utilise energy?
yes, but it does not need metabolic energy and instead uses the natural motion of particles
equilibrium
balance of concentrations
does equilibrium mean that the particles stop moving?#
no, there is just a balance in movements
selectively permeable membrane
membrane with protein channel
term for cell-surface membrane bends inwards
invaginates
solute
substance that is solved in a solvent to form a solution
solvent
dissolves substances to form a solution
water potential
pressure that is exerted by water molecules as they collide with a membrane or container
when does osmosis occur
when water solutions of two different water potentials are separated by a partially permeable membrane
what moves during osmosis
water molecules two equal concentrations
cytolysis
water potential outside of cell is higher
–> cell bursts
(animal cells)
crenation
water potential outside of cell is lower
–> cell shrinks
(animal cells)
turgor
pressure that cell wall experiences when water enters the cell
turgid
cell wall resists entry of more water
plasmolysed
cell membrane pushed away from cell wall
