Transport Across Membranes Flashcards
What is lipid/simple diffusion?
- lipid soluble/ non polar (uncharged) molecules and small molecules like oxygen pass through phospholipid bilayer
- water soluble does not pass through
- higher to lower concentration
- passive process
What does it mean when a method of transport is passive?
Doesn’t require ATP
What are the factors effecting lipid /simple diffusion?
- concentration gradient (higher it is, faster)
- thickness of exchange surface (thinner it is, faster as shorter distance)
- surface area ( larger it is, faster)
What is osmosis?
- movement of water molecules from an area of higher water potential to an area of lower water potential through a partially permeable membrane
- passive process
What are the factors affecting osmosis?
- water potential gradient (higher it is, faster)
- thickness of exchange surface (thinner it is, faster as shorter distance)
- surface area of exchange surface (larger it is, faster)
What is facilitated diffusion?
- diffusion of polar molecules and charged ions through the membrane proteins (channel and carrier)
- passive process
What are the factors affecting facilitated diffusion?
- concentration gradient (higher it is, faster)
- number of channel or carrier proteins (can’t speed up diffusion once all proteins in membranes are in use)
What is the difference between carrier proteins and channel proteins?
Carrier proteins change its shape when binding with a specific complementary polar molecule or charged ion to release on opposite side of membrane
What is active transport?
- active process
- movement of ions or molecules across a cell membrane from a region of lower concentration to a region of higher concentration assisted by enzymes and requiring energy
- uses carrier proteins
- protein pump
What does it mean when a method of transport is active?
Requires ATP
How does ATP release energy for active transport?
ATP is hydrolysed to release ADP + Pi and energy
Why is protein pump only in active transport?
It requires ATP
What are the factors affecting active transport?
- speed of individual carrier proteins (faster they work, faster the rate)
- number of carrier proteins present (more proteins present, faster the rate)
- rate of respiration in cell and availability of ATP (if respiration is inhibited, active transport can’t take place)
What is cyanide and its effect on active transport?
- Respiratory inhibitor
- stops respiration which stops ATP production so no active transport can occur
In plant cells what is the water potential dependant on?
Solute potential and pressure potential
