bye later ( phospholipid) Flashcards
is the phosphate head hydrophobic or hydrophilic
hydrophilic
is the hydrocarbon tail hydrophobic or hydrophilic
hydrophobic
what is the cell surface membrane
forms a boundary between the cell cytoplasm and the outside environment. it allows different condition to be established inside and outside of the cell and controls the movement of substances inside and outside of the cell
what does hydrophilic mean
attracting water
what does hydrophobic mean
repels water
how do lipid soluble molecules move through the bilayer?
move through the phospholipid portion,
what si the function of the phospholipid bilayer?
- allow lipid soluble molecules to move through
- prevent water soluble molecules entering or leaving the cell - preventing osmotic lysis
-make the membrane flexible and self sealing
what do proteins do in the bilayer
act as receptor cells or cell recognition and in conjunction with glycolipids
what is a phospholipid
lipids with a phosphate group
are phosphate positively or negatively charged
negatively
what is an extrinsic protein
attach only to the outside of the phospholipid
what is an intrinsic protein
spans across the whole bilayer
what is a glycoprotein
proteins with short carbohydrate chains attached
what is a glycolipid
lipid with a short carbohydrate chain attached but is also involved in cell recognition and receptors
what is the function of cholesterol
will reduce membrane fluidity!!!!!!! and fits in-between the phospholipid
protein channels - what do they do
allows smaller molecules to pass through the bilayer
why do some molecules not diffuse easily across the bilayer
- not soluble in lipids and therefore cannot pass through the bilayer
- too large to pass through the protein channels
- of the same charge as the protein even of they are small enough they will be repelled
- if they are polar molecules so will therefore have difficulty passing through the non-polar hydrophobic tails
describe the fluid mosaic model
- fluid - phospholipid molecules can move relative to one another- this gives the membrane a flexible structure taht is constantly changing
- mosaic - the protein in the bilayer vary in shape, size and pattern
how does cholesterol reduce membrane fluidity??
pulls together fatty acid tails of the phospholipid molecules and therefore restricting movement but without making the whole molecule rigid
what are the general function of MEMBRANES
entry and exit of materials synthesised by mitochondria or chloroplasts or the other way round
- separate organelles from cytoplasm so that specific metabolic processes can atke place
- isolating the rest of the cell from damaging lysozymes
- provide surfaces on which reactions can occur e.g. protein synthesis using ribosomes on the RER.
