Diffusion And Co Transport Flashcards
Definition of diffusion
- a passive movement of molecules from an area of high concentration to an area of low concentration until equilibrium is reached
How does simple diffusion work?
- only occur in gas and liquid
- molecules move by its KE that already possess = so can move constantly
- the motion is random
- only lipid soluble and small molecules can diffuse through the membrane
- a passive process
3 factors affect rate of diffusion
- concentration gradient
- surface area
- thickness of membrane ( distance)
Facilitated diffusion
- uses proteins of membrane to transport molecules e.g. water soluble ions + large molecules
How does channel proteins help in F. Diffusion
- it forms a water filled hydrophilic tubes = allow water soluble (polar) ions to diffuse in membrane
- it is selective which only open to certain ions when they bind to them = so have control over enter or exit of ions
How does carrier proteins help in F. Diffusion ?
- it binds with large molecules e.g. glucose = cause a change in shape of the protein = enable to diffuse through
What law use in measuring rate of diffusion?
Fick’s Law
Formula of fick’s law
Rate of diffusion = SA x difference in conc. / membrane thickness
defintion of osmosis
- the passive net movement of water from an area of higher water potential to an area of lower w.p across a partial permeable membrane
What is water potential ?
- pressure created by water molecules
- kPa
Trend of water potential
- more solute in the solution ( higher conc.) = lower water potential
- water move from high w.p (less negative ) to lower w.p (more negative )
Isotonic meaning
- when the w.p of the solution is the same with the w.p of the cell
Animal cell in different condition of water
- hypotonic = burst
- hypertonic = shrivelled
- isotonic = balance equilibrium
Plant cell in different water condition
- hypotonic = turgid
- hypertonic = plasmalysed
- vacuole will get smaller / bigger as water enter / exit the cell
Active transport
- the movement of molecules in or out of the cell from an area of lower conc. to higher conc. using ATP and carrier proteins
ATP role in active transport
- directly moving molecules
- co transport - move molecules individually using conc. gradient
How does ions/ other molecules pass through A.T ?
- ATP binds to carrier proteins = change shape = enable pass through
- certain molecules bind to receptor site on C.P = ATP bind protein in the inner membrane, hydrolysis to ADP + Pi = protein change shape, Pi then released from protein
What is the process used to get Na and glucose from ileum to epithelial cell ?
Co transport using facilitated diffusion through a carrier protein
What is the role of villi in co transport ?
- provide large SA for CT to happen, thin membrane walls for transportation and rich network of blood capillaries
What is the full process of Na + G to blood in order ?
1) AT from epithelial cell to blood = bring Na to blood
2) epithelial cell stay low conc.
3) CO transport = to get Na with glucose from ileum to epithelial cell using carrier protein
4) facilitated diffusion used to get Na + G from e.c to blood to maintain high conc of glucose in blood stream or respiration
Explain how shape of ATP synthase allow to catalyse synthesis of ATP and allow movement of H+ ions ? (4)
1) active site of enzyme complementary to ADP and pi
2) so more enzyme substrate complex forms
3) allow the use of channel proteins by the use of ATP
4) diffuse H+ ions by F.D
