membranes as permeable bariers Flashcards
what is a semipermeable membrane
it is s phospholipid bilayer which only allows diffusion of specific molecules across it
which molecules are allowed to diffuse across membrane bilayer
non-polar molecules e.g o2 and small polar molecule e.g h2o. BUT charged molecule or large polar molecules cannot cross
what was the black film experiment
used black film with Pinole. when membrane formed pinhole no longer seen when light shined from other size
types of facilitated diffusion channels
pingping, ligand gated, voltage gated or ligand gated ATP sensitive channels meaning when ATP is high it binds and closes the channel
how can you describe active transport
moving molecules from low conc to high conc (against conc gradient) it is active or moving positive charged molecules into a more positive lumen. These all have positive delta G. Don’t happen spontaneously
what happens when conc gradient or membrane potential increases
delta G increases and more energy needed. Energy for this is provided by the hydrolysis of ATP
concs of different ions inside and outside the cell
potassium is high inside and calcium, chloride and sodium and high outside the cell
ATPase channel
hydrolysis of ATP pumps calcium out of cell
ATPsynthase channel
ATP synthesised as H+ diffuses into the cell (oxidative phosphorylation)
Na+/K+ ATPase
Na+ is pumped out by the hydrolysis of ATP and K+ leaves cell. This generates the concentration gradient
Na+/Ca2+ exchanger
secondary transporter. uses energy of sodium potassium pump so that as 3Na+ enter down the conc gradient a Ca2+ leave
Na+/H+ exchanger
secondary transporter. uses energy from sodium potassium pump to remove H+ from cell as 3Na+ diffuse in down their conc gradient
Na+/Glucose transporter
secondary transporter. As 3Na+ diffuses in glucose diffuses with it. uses energy of conc gradient set up by sodium potassium pump
describe the technical terms for the different types of co-transport
when more than 1 type of molecule/ion is transported by one protein. uniport=1 molecule. symport= more than 1 going same direction. antiport= more than 1 going opposite directions
what causes cystic fibrosis
CFTR gene codes for protein which pumps cl- out of the cell. water follows by osmosis and makes mucous moreliquidy and less thick but in cystic fibrosis this gene is defective so mucous is thick and sticky and blocks airways
