cellular membranes Flashcards
what is the role of the plasma membrane
act as a barrier between the cell and their environment
why are plasma membranes described as being partially permeable
some molecules can pass through but others cannot
what do plasma membranes allow
recognition of other cells and cell signalling
what is the role of membranes within cells
membranes around organelles divides the cell into its separate components
what can membranes within a cell form
vesicles
what are vesicles useful for
transporting substances around the cell
how is membranes within cells responsible for transcription
allows mRNA to leave nucleus via nuclear membrane
what can membranes within cells be the site of
reactions, eg inner membrane of mitochondria contains enzymes for respiration
what molecules is the cell membrane composed of
phospholipid bilayer
how does the fluid mosaic model describe the phospholipid bilayer
it is fluid as phospholipids are constantly moving as it is a mosaic as proteins are randomly arranged throughout
what lipid molecules are present within the bilayer and what is their role
cholesterol, impact fluidity
describe the phospholipid bilayer
heads of phospholipids and hydrophilic and the tails are hydrophobic
molecules arrange themselves into a bilayer with their heads facing outwards and tails facing inwards
what substances does the phospholipid bilayer not allow through
polar as the hydrophobic tails repels this and molecules that are too large as cannot fit between phospholipids
how does cholesterol work at high temperatures
pushes the phospholipids closer together to decrease fluidity
what do channel proteins do
allow charged/ large molecules to pass through via facilitated diffusion
