cell membrane Flashcards
(28 cards)
structure and function of cell membrane
separates contents of cell from external environment
fuild mosaic model explains it becasue its constantly moving and therea re many molecules
phospholipid bilyaer containing phosphate group
describe the bilayer
phospholipid bilayer and each molecule has a hydrophilic head and hydrophobic tail.
what is the purpose of cholestrol in the membrane adn where is it
embedded in the bilayer and ensures that the acid fatty tails do not stick together sp that it is flexoble but aslo makes sure tp add rigidity so that the membrane is not too fluid
what do carbohydrates do
involved in communication and cell recognition. allows cells to identify each other as part of the same organism or detect foreign invaders like bacteria and viruses
waht are glyco proteins
glycoproteins are carbohydrates that are attached to proteins
what are glycolipids
carbs that are attached to the phospholipid
what are integral proteins
proteins embedded into the membrane or span the entire membrane and act as channels and carriers for the transport of molecules such as ions, nutrients, and waste products. aslo serve as receptors for signalling molecules so the cell can respond to external signals.
what are peripheral proteins
proteins attached to the surface of the membrane and assist in support, signalling and interactions with teh cytoskeleton
explain membrane receptors
specialised proteins that help deted and respond to specific molecules such as hormones. these receptores will only bind to one type of molecule which will then trigger changes in the cells activity
explain transport across the membrane
the membrane is semi permeable and only allows certain ions and molecules to pass through
transport of materials across the membrane can occur by which processes
diffusion, facilitated transport, and vesicular transport
is diffusion a passive or active tranport
passive
is facilitated passive or active
can be both but mainly passive
is vesicular transport passive or active
active
what is diffusion
the spreading out of particles from an area of high concentration to an area of low concentration.
what does diffusion occur in
gases and liquids
what is the conc gradient
the difference in concentration that brings about diffusion
what causes faster rate of diffusion
greater difference in the concentration gradient causes the diffusion gradient to be steeper
define simple diffusion
a process of substances moving along the conc gradient in a solution or across a semi permable membrane without the use of membrane protein. (passive- js happens without energy)
define osmosis
diffusion of a solvent through a differentially permeable in order to balance the concentration of another substance. diffusion of water only
water will move from an area where solute such as sugar is low in conc to where an area the solute is high in concenctration.
define tonicity
ability of a surrounding colution to cause water to move into or out of a cell by osmosis. hihc is determined by the conc of solutes outside compared to inside
three types of solutions in relation to tonicity
isotonic, hypotonic, hypertonic
what is a isotonic solution
conc of solutes is the same inside and outside of the cell so cell size remains constant
what is a hypotonic solution
solute conc is lower outsite so it will swell and maybe burst
