Biology - 2.3 - transport across cell membranes
describe the structure of a phospholipid
one hydrophilic phosphate head and two hydrophobic phosphate tails. heads face outwards and tails face inwards
describe the function of the phospholipid layer
impermeable membrane to water due to hydrophobic centre, permeable to lipid molecules which may dissolve and pass right through
which part of phospolipids are polar
head is polar, tail is non polar
why is it referred to as the fluid-mosaic model
fluid because it is moving, fleixble, and liquid like
mosaic because made of different proteins and phospholipids
describe the structure of cholesterol
consists of a hydrophilic and hydrophobic region, mostly hydrophobic
hydrophobic region binds itself to the phospholipid tails, binding them closely together
describe the function of cholesterol
adds strength by binding phospholipid tails closer together
reduces the fluidity of the membrane and makes more stable
describe the structure of an intrinsic protein
embedded all the way through the bilayer
full of water so moves water soluble substances through the membrane
describe the function of an intrinsic protein
provides structure to the bilayer
transports water soluble substances
describe the function of an extrinsic protein
provide support to membrane and involved in cell signalling
describe the structure of an extrinsic protein
present on one side of the bilayer, hydrophilic R groups on outer surface and interact with polar heads of phospholipids or intrinsic proteins
describe the structure of a glycolipid
a glucose chain bonded to a lipid (phosphate head)
describe the function of a glycolipid
used for cell recognition and adhesion
describe the structure of a glycoprotein
glucose chain bound to a protein
describe the function of a glycoprotein
a receptor site for communication, neurotransmitters, and hormones