biological membranes (chapter 5) Flashcards
components i a membrane
glycolipid
intrinsic protein
extrinsic protein
phospholipids
carbohydrate chain
glycoprotein
cholesterol
phospholipid bilayer
instrinsic protein
- span the membrane
- held together by the interactions of the hydrophobic core and the R groups on the proteins
- channel proteins : allow passive movement of some substaces that are too big to fit through the phospholipid bilayer.
- carrier proteins : actively and passivley move substances accross the membrane, often changes shape.
extrisic proteins
Sit on one side of the membrane
- they susually have hydrophillic R groups and intercat with the polar.
glycoproteins and glycolipids
glycoproteins : carbohydrate chain attached to a protein
- are intrinsic proteins
- cell adhesion
- receptors for chemical signals
glycolipids :
similar to glycoproteins, are lipids with a carbohydrate chain attatched to it
- are intrinsic proteins
- they are antigens that can be recognised by the cells in the immune system
cholesterol
helps to maintain the fluidity of the membrane, preventing it from becoming too rigid when temperatures drop and fluid sits between phospholipids.
osmosis
the diffusion of water accross a partially permeable membrane.
how doe these molcules move accross a membrane?
proteins
ions
glucose
pathogen
O2 or CO2
proteins, endocytosis
ions, faciliatred diffusion
glucose : active transport
pathogen, endocytosis
O2 or CO2, diffusion
water potential
- pure water has a water potential of 0
- Water moves from a solution with a higher water potential to a solution of a lower water potential.
explain the process of endocytosis
the cell membrane folds inwards ( the cell membrane knows to do this because the receptors bind to the molecule) then the membrane pinches off to forma vesicle. The cell needs ATP to do this.
