Diffusion, Osmosis and Active Transport Flashcards
Define diffusion
the net movement in molecules or ions from a region of their high conc to their lower conc
When is there no net movement
when uniform conc is achieved
Are particles ever still
no, they are constantly moving in random directions
Name 5 factors affecting diffusion
steepness of conc gradient temp thickness of membrane surface area type of molecule
The higher the temp the what
more kinetic energy and faster the rate of diffusion
Which type of molecule diffuse easier
polar rather than non polar
Explain oxygen, co2 and waters diffusing tendencies
oxygen and co2 - non polar but small so quick
water - polar and small so quick
What affects rate more, pole or size
size
Why is facilitated diffusion needed
as large molecules cannot diffuse across the bilayer such as glucose and amino acids
Explain facilitated diffusion
molecules pass through protein channels
passive
still needs conc gradient
slower due to larger molecules and SA
Explain the protein channels
water filled hydrophilic channels
allow specific water-soluble ions to pass
ions bind with protein causing it to change shape
Explain carrier proteins
involves specificity
when specific molecule binds with carrier protein it causes the protein to change shape
Define osmosis
the diffusion of water from an area of high water potential to low water potential across a semi-permiable membrane
Define water potential
the tendency of water to move from one area to another
What water potential does pure water have
0
What does adding solute do to the water potential
lowers it
Define active transport
the movement of ions into or out of a cell from a region of lower conc to a higher using energy and carrier molecules
Give 4 reasons why it differs to diffusion
requires metabolic energy in the form of ATP
molecules are moved against gradient
uses pumps in the form of carrier molecules
only selected molecules are transported
