cell membranes Flashcards
how much fatty acids do triglycerides have
3 bonded to one molecule of glycerol
describe the polarity in a triglyceride
non polar which makes them hydrophobic and insoluble to water
phospholipid structure -molecular
two fatty acid bonded with one glycerol via esta bond and a phosphate group
polarity of a fatty acid
non polar hydrophobic
polarity of phosphate group
charged which means it is polar and hydrophilic
general structure of a phospholipid
non polar hydrophobic tails and a hydrophilic polar head
how are phospholipids arranged with water
the hydrophilic heads interact with the water but the fatty acid are burried in the center away from water -phospholipid bi layer
membrane functions
act as barriers, between the internal content of the cell and the external environment
2.or between the contents of an organelle and the cytoplasm
3, chemical reactions
4. cell signalling
hydrophobic center means that
hydrophobic molecules can easily pass through
however prevents hydrophilic water soluble molecules from easily passing through
things with a charge cant easily pass through the non polar region of the membranes
why is water an exception even when its polar
it is extremely small
what other things in the cell surface membranes
protein’s and cholesterol
cholesterol hydrophilic group is found where
contains a hydrophilic group at one end this group can attract the polar head group on the phospholipid molecules
the rest of the cholesterol is nonm pollar and can attract the fatty acids in the phospholipids
cholesterols function in phospholipid
it increases the strength of the cell surface membrane and makes it more stable and less likely to be damaged
reduces the sideways movement of phospholipids
it controls the fluidity. helps the membrane from becoming too fluid in warm conditions
-helps reduces the movement of water soluble molecules across the cell surface membrane
fluid mosaic model
fluid-the phospholipid molecules can move around each layer - flexible and change shape
mosaic because its studded with proteins
what two categorises can membrane proteins be categorised into
-intrinsic or extrinsic proteins
-intrinsic proteins
are fully embedded in the membrane from omen side to the other
hydrophobic amino acids in intrinsic proteins
because they pass right through the bilayer the inrisc proteins have hydrophobic amino acids on the outside surface and can interact with the fatty acids in the bi layer
what are two types of intrinsic proteins
carrier proteins and protein channel
protein channel
the chanel runs through the center lined with hydrophilic amino acid and filled with water molecules
what do protein channels allow through
water soluble molecules and ions to diffuse through
carrier proteins
can change shape or position to transfer molecules or ions from one side of the membrane to the other
extrinsic proteins location
do not span the membrane found on one side or the other
extrinsic protein role
-structural role other acts as enzymes and some are receptors for hormones
whats a glycoprotein
is a carbohydrate attached to membrane proteins
function of glycoproteins
allow cells to attach to each other
immune system: presenting antigens to t cells
receptors for hormones
carbohydrase attached to phospholipid molecules
glycolipids
glycolipid function
when cells come in contract with one ecohotel
act as antigens
