Biological Membranes Flashcards
Fluid mosaic model
Theory of cell membrane structure with proteins embedded in the sea of phospholipids
Glycolipid
Lipid/phospholipid with a chain of carbohydrate molecules attached
Glycoprotein
Protein with a chain of carbohydrate molecules attached
Plasma membrane
Cell surface membrane
osmosis
water moves from high water potential to low water potential down a water potential gradient through a partially permeable membrane
features of osmosis
the more concentration, the more solute so the more water molecules tied therefore, there are less water molecules free to take part in osmosis passive process (requires no energy) partially permeable water potential gradient equilibrium
hypotonic solution
a dilute solution with not many solutes
hypertonic solution
concentrated solution with many solutes
isotonic solution
equal concentration of solutes and water
cytolysis
in animal cells, if a lot water molecules enter, the cell will swell and burst as the plasma membrane breaks
turgid
in plant cells, the rigid and strong cellulose wall will prevent bursting. the cell will swell up to a certain size when its contents push against the cell wall which will resist any further swelling. turgidity of plant cells help support plants especially those that aren’t woody
crenated
when animal cells shrivel
plasmolysed
when the cytoplasm of plant cells shrink and the membrane pulls away from the cellulose wall, they suffer a degree of dehydration and their metabolism can’t proceed as enzyme-catalysed reactions need to be in solution
flaccid
plant tissue with plasmolysed cells
diffusion
movement of molecules from an area of high concentration of that molecule to an area of low concentration (may/may not be across a membrane, doesn’t need ATP)
facilitated diffusion
movement of molecules from high concentration to an area of low concentration across a partially permeable membrane via channel proteins (doesn’t involve ATP)
water potential
measure of the tendency of water molecules to diffuse from one region to another
active transport
the movement of substances against their concentration gradient (from low to high concentration) across a cell membrane using ATP and carrier proteins
endocytosis
bulk transport of molecules too large to pass through a cell membrane into a cell, an active process via vesicles that ‘fuse’ with the cell using ATP
exocytosis
bulk transport of molecules too large to pass through a cell membrane out of a cell, an active process via vesicles that are ‘pinched off’ using ATP
what is active transport affected by
low temperature and lack of carbon dioxide
sodium-potassium pump
the mechanism in active transport of moving sodium and potassium ions across the membrane
bulk transport
some cells need to transport large molecules and particles that are too large to pass in and out the plasma membrane so they move via vesicles in endocytosis and exocytosis
All proteins in the plasma membrane
Transmembrane Carrier Peripheral Channel Glycoproteins
Other parts to plasma membrane
Phospholipids
Glycolipids
Carbohydrate molecules
Cholesterol
In high water potential, cells can become
Cytolysed (animal)
Turgid (plant)
In low water potential, cells can become
Crenated (animal)
Plasmolysed (plant)
Does high water potential have high or low pressure
Low
Does low water potential have high or low pressure
High
function of phospholipids
control what enters/exits cell
function of integral (inside membrane) proteins
transport molecules in/out of cell
function of glycolipids/glycoproteins
cell recognition, cell signalling, receptors
function of peripheral (outside membrane) proteins
enzymes
function of cholesterol
maintains stability and fluidity of the cell by preventing it becoming too stiff when temperature is too high/low
glycocalyx
chain of carbohydrate molecules
function of glycocalyx
very hydrophilic on the outside, attracting water with dissolved solutes, helping the cell to interact with its watery environment and obtain dissolved substances
hydrophilic…
head
hydrophobic…
tail
betalain
red pigment that leaks out of beetroot when temp increases and membrane becomes more permeable