restricts the movement of othermolecules making up the membrane and increases strength and stability of membranes by making them lessflexible. Helps to prevent loss of water
glycolipids?
made of carbohydrates and glycolipids covalently bonded to each other, also act as a recognition site, helping to maintain the staility of the mebrane
glycoprotein?
short branching carbohydrate chains are attached to the proteins in the membrane.These glycoproteins act as receptors for hormones and neurotransmitters or antigens
fluid mosaic?
membrane proteins floating around in the structure. Extrinsic is hen the proteins may be in one layer and (intrinsic) proteins across the whole layer
which substances would be able to move through the hydrophilic channels?
large polar substance soluble such as glucose ions and amino acids.
diffusion and osmosis are passive processes
Factors affecting the rate of diffusion?
- the surface area over which diffusion occurs
- the thickness of the exchange surface
- the concentration gradient
- the size of the diffusing molecule
- temperature
- water solubility/polarity
to increase diffusion rate?
maximise the surface area
maximise the concentration difference
maximise the thickness if exchange surface
what molecules will be able to move through the phospholipid bilayer by simple diffusion and why?
molecules that are non polar will be able to diffuse across the mebrane because they are lipid soluble and will not be repelled by the fatty acids in the hydrophobic tails. Smaller molecules can also diffuse through more easily as they can fit between phospholipid molecules such as oxygen molecules. They are non-polar and are small enough to squeeze through the membranr