2.4 Passive & active transport, endo and exocytosis, carrier & channel proteins

Vesicles fuse with cell membrane to release contents

Exocytosis

Vesicles created from membrane to take substances into cell

Endocytosis

channel proteins

Span membrane and make hydrophilic tunnels across it, allowing water molecules and ions to diffuse through

carrier proteins

Molecule binds to specific site on the protein, before it changes shape to transport it across the membrane

shape

Energy from ATP changes the _____ of the protein in active transport

-one phosphate group removed by hydrolysis

-once removed it becomes hydrated

-lot of energy released as bonds form between water and phosphate

How does ATP release energy?

-diffusion occurs down a concentration gradient, whereas active transport occurs against a concentration gradient

-both move molecules through the phospholipid bilayer

-in both, molecules can move through proteins

-diffusion is passive, whereas active transport requires ATP

Compare and contrast diffusion and active transport (3)

prite

What does exocytosis transport?

-both use integral proteins

-both move polar substances

-FD moves substances down a concentration gradient, AT moves substances against

-FD uses carrier or channel proteins, AT uses carrier only

-FD passive process, AT active

Compare and contrast the processes of facilitated diffusion and active transport (5)

-Both transport very large polar or non polar substances, e.g. proteins

-Both use vesicles

-Both are active processes, requiring ATP

-Exo involves mass transport out of cell, endo involves mass transport in

-Exo, vesicle fuses with the cell membrane to release substances, endo vesicle formed from the cell membrane to take in susbtances

Compare and contrast the processes of endocytosis and exocytosis (5)

-facilitated diffusion, through channel or carrier proteins, as it cannot move through the phospholipid bilayer via diffusion due to being charged

-active transport through a carrier protein if moving from low to high conc.

Substance A is a charged molecule. Explain which forms of transport it could use to cross a membrane (2)

-ATP hydrolysed to release energy and to become ADP and Pi

-energy used to change the shape of carrier protein to enable substances to move from low to high concentration

Explain the role of ATP in active transport (2)