fluid mosaic model Flashcards
describe the fluid mosaic model
molecules free to move laterally in the phospholipid bilayer
many components including phospholipids and proteins glycolipids and glycoproteins
arrangement of components of cell membrane
phospholipids - form bilayer
fatty acid tail face inwards and phosphate heads face outwards
intrisinc proteins span bilayer eg carrier and channel
extrinsic protiens on surface of membrane
glycolipids and glycoproteins found on exterior surface
cholesterol bonds to phospholipids hydrophobic fatty acid tails
arrangement of phospholipids in a cell membrane
bilayer with water present on either side
hydrophobic fatty acid tail repel from water so point away from water
hydrophilic phosphate head attracted to water so point to water
cholesterol role
restricts movement of other molecules making up membrane
decreases fluidity
increases rigidity
how cell membranes adapted for other functions
phospholipid bilayer is fluid so membrane can bend for vesicle formation
glycoproteins and glycolipids act as receptors and antigens involved in cell signalling and recognition
simple diffusion
lipid soluble or small move from area of high conc to low conc
down conc gradient
across phospholipid bilayer
passive so dont require energy from ATP
facilitated diffusion
water soluble larger
mov down conc gradient
through specific channel and carrier protiens
passive so doesnt require energy from atp
carrier and channel protiens role in FD
shape and charge of protein determines which substances move
channel facilitate diffusion of water soluble substances as they are a hydrophobic pore filled with water which may be gated so can open and close
carrier facilitate larger
Complementary substance attaches to binding site so protiens change shape to transport substances
osmosis
water diffuses from area of high WP to are of low WP
through a partially permeable membrane
passive so doesnt require energy from atp
active transport
substances move from area of low conc to high conc against conc gradient
require hydrolysis of ATP and specific carrier protiens
Describe the role of carrier proteins and the importance of the hydrolysis of
ATP in active transport
comp substance binds to specific carrier protein
ATP binds
hydrolysed to ADP AND PI releasing energy
carrier protein changes shape releasing substance on side of higher conc
pi released protien returns to original shape
cotransport na
NA AT from epithelial cells to blood
establishing a conc gradient of na
na enters epithelial cells down its conc gradient with glucose against its conc gradient
via a co transporter protein
glucose moves down conc gradient into blood via FD
Describe how surface area, number of channel or carrier proteins and
differences in gradients of concentration or water potential affect the rate of
movement across cell membranes
increase surface area increases rate of movement
Increasing number of channel / carrier proteins increases rate of facilitated diffusion active transport
Increasing concentration gradient increases rate of diffusion and osmosis
○ Until number of channel / carrier proteins becomes a limiting factor as all in use / saturated
● Increasing water potential gradient increases rate of osmosis
Explain the adaptations of some specialised cells in relation to the rate of transport across their internal and external membranes
folded membrane incr SA
more Protein channel and carriers for FD OR AT
lots of mitochondria making atp by aerobic respiration for AT
meaning of processed results
raw data. - has initial and final masses
