Semi-permeable means does not allow everything to pass freely inside-out
Structure of Cell Membrane
Fluid Mosaic Model
Sandwich Model
FluidMosaicModel
Moves around
Gives Cell Membrane flexibility
Fluid - movement, floating around they're not static
Mosaic - arranges small pieces together to make some large piece
Polar - dissolved in water (Ex. Water)
Non Polar- won't dissolve in water (Ex. Oil)
Phospholipid Bilayer
Hydrophilic Head
Loves Water
Polar
Two Hydrophobic Tail
Hates Water
Non-polar
Phospholipid Bilayer
makes up the cell membrane
protects cells
bilayer - it has two layers of molecules called phospholipids
Phospholipids bilayers border the whole cell
Phospholipids Bilayer
Cholesterol
Proteins
Carbohydrates
Cholesterol
If temperatures drop, the cholesterol can function as spacers between the phospholipids keeping them becoming too packed
Vice versa, the cholesterol can function to connect phospholipids to keep them from becoming to fluid in warm temperatures
Proteins
Integral Proteins
Peripheral Proteins
Peripheral Proteins
exterior area of the membrane
more loosely attached since they are not generally stuck
Acting as enzymes to speed up reaction, attaching to the cytoskeleton structures to help with the cell shapes
Integral Proteins (transmembrane proteins)
go through the membrane (connecting both the inside and outside of the cell.)
peripheral proteins can sit on them
transporting methods for all kinds of materials
Example
Consider you ate breakfast and your body digest what you ate for breakfast to obtain glucose
Once in the bloodstream, those glucose molecules can't just squeeze through the phospholipid bilayer to enter to your cells. The glucose molecules are too big and polar
But your cells need glucose to survive to make ATP and then gets in Integral Protein
GLYCOLIPID - carbohydrates attached to the lipid
GLYCOPROTEIN - carbohydrates attached to the protein
GLYCOLIPID AND GLYCOPROTEIN
Fightingpathogens
Cellsignalling
GLYCOPROTEIN known as CD4
found on the surface some of your immune cells
essential for some of these immune cells to interact with each other and activate