Cell membrane composed of
Phospholipid bilayer
barrier to water soluble substances, NOT to any small molecules and lipid soluble molecules
5 types of membrane proteins
2 types of transport proteins
- carrier porteins
Channels on cell membrane
form pore in membrane, selectively permit channel/medicated facilitated diffusion of water and specific ions
Channels on cell membrane can be..
- non gated (leakage channels) always open
Receptor proteins
can bind specific ligands
Ligands
extracellular molecules (ex: hormones, neurotransmitters)
Carrier proteins
bind solute and carry it across membrane, allow protein carrier mediated facilitated transport OR active transport
Example of receptor proteins
Enzymes
control chemical reactions on outer or inner surface, CAN BE A PROTEIN
Identifying proteins
identify cell as “self” (part of body) not foreign
Example of identifying proteins
major histocompatibility complex (MHC) proteins on surface of all cells except rbc
Membrane carbohydrates
glycoproteins and glycolipids. differ for every cell type, allows cells to recognize other cells
Example of membrane carbohydrate
sperm recognizing a an egg
Membrane transport
movement of material between intra and extra cellular fluids`
Solute
substance dissolved in a solution
Solvent
substance solute is dissolved in
2 types of transport
- passive transport
Passive transport
no NRG required (no ATP).
Diffusion
movement from a high to low concentration
The greater the difference in concentration =
the more molecules want to move
Types of passive transport
Simple diffusion
solute diffuses through cell membrane bilayer (small, lipid soluble) ex: O2, CO2