Movement Across Membrane - Apoptosis Flashcards
How do hydrophobic molecules move across the membrane
( o2 , co2 , N2 ) pass rapidly across the bilayer.
How do small uncharged polar molecules cross the membrane ?
( h2o , urea , glycerol ) pass readily but at a slower rate as they are capable of dissolving in bilayer.
How do large uncharged polar molecules cross the membrane ?
( glucose and sucrose ) cannot pass through
How do ions cross the membrane
( H+ and mg2+ ) pass through the proteins but not the Bilayer.
How do small hydrophobic molecules pass across the membrane ?
Pass readily through membrane by diffusion. Phospholipid bilayer acts as a barrier to ions and most large uncharged polar molecules - these molecules can still pass but do so through membrane proteins; channel and transporter.
How do non gated channel proteins work?
Passive - use simple diffusion and osmosis from high to low concentration.
How do ligand gated channel proteins work?
Passive - when the ligand binds to the protein it opens , allowing molecules to pass through, when the ligand detaches the protein closes.
How do voltage gated channel proteins work?
Change in ion concentration / change in voltage opens the protein. When voltage gradient returns to normal the protein closes.
How do facilitated transporter proteins work?
Passive - a change in conformation will bring about transport e.g. Glucose
How do active transporter proteins work?
Requires energy (ATP) to bring about a conformational change of protein to allow transport e.g, sodium / potassium pump
