MOVEMENT OF MATERIALS

CChristine
Mind Map by CChristine, updated more than 1 year ago
CChristine
Created by CChristine over 5 years ago
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Chrstine lee 4th September 2014

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MOVEMENT OF MATERIALS
1 PASSIVE TRANSPORT
1.1 Process does not require Energy
1.2 Diffusion
1.2.1 random movement of particles from an area of high concentration to an area of low concentration
1.2.2 higher the concentration gradient
1.2.2.1 higher the rate of diffusion
1.2.3 factors affecting rate of diffusion
1.2.3.1 size
1.2.3.1.1 small particles diffuse faster than larger paticles
1.2.3.2 temperature
1.2.3.2.1 particles diffuse faster at high temps than low temps due to more kineticE
1.2.3.3 state
1.2.3.3.1 gas>liquid>solid
1.2.3.3.1.1 gas particles have highest kineticE, then liquids, then solids
1.2.4 small molecules diffuse freely across membranes along the concentration gradient
1.2.4.1 however, large molecules are prevented from diffusing through membrane
1.3 Facilitated Diffusion
1.3.1 special trasport/carrier proteins in the membrane provide channels for the process
1.3.1.1 carrier proteins are specific
1.3.1.1.1 i.e. only carry 1 type of molecule
1.3.2 e.g. both oxygen and glucose are facilitated
1.3.2.1 due to high demand for oxygen and glucose in cells
1.3.3 passive process
1.3.3.1 molecules can only diffuse from high conc -> low conc across membrane
1.4 Osmosis
1.4.1 movement of water from an area of high water potential to an area of low water potential across a semi-permeable membrane until water potentials are equal
1.4.2 few solutes dissolves
1.4.2.1 high water potential
1.4.3 weak/dilute solution
1.4.3.1 hypotonic
1.4.4 strong/ concentrated solution
1.4.4.1 hypertonic
1.4.5 2 solutions with equal water potential
1.4.5.1 isotonic solutions
1.4.6 particles move in both directions across membrane,
1.4.6.1 however, net movement is towards area of lower water potential
1.4.7 Osmoregulation
1.4.7.1 control of water inside a cell or organism
1.4.7.2 both plant and animal cells
1.4.7.3 no net loss or gain of water in an isotonic solution
1.4.7.4 net loss of water in a hypertonic solution
1.4.7.5 net gain of water in a hypotonic solution
1.4.7.6 animal cells in:
1.4.7.6.1 isotonic
1.4.7.6.1.1 no change. normal
1.4.7.6.2 hypertonic
1.4.7.6.2.1 dehydrated- shrivels. net loss of water
1.4.7.6.3 hypotonic
1.4.7.6.3.1 burst. excessive net gain of water
1.4.7.7 plant cells in:
1.4.7.7.1 isotonic
1.4.7.7.1.1 no change. no net gain / loss of water
1.4.7.7.2 hypertonic
1.4.7.7.2.1 plasmolysed- membrane pulls away from cell wall and cell becomes flaccid
1.4.7.7.3 hypotonic
1.4.7.7.3.1 turgid. firm. cell wall prevents cell from bursting- high turgor pressure
2 ACTIVE TRANSPORT
2.1 Process requires energy
2.2 moves substances across membrane against concentration gradient
2.2.1 i.e. from low conc -> high conc
2.3 e.g reabsorption of glucose by kidney tubule cells by active transport
2.4 e.g. uptake of nitrates by root hairs
2.5 carrier protein combines with substance
2.5.1 carrier protein changes shape
2.5.1.1 substance is released to the other side of the membrane
2.5.2 carrier proteins= specific to which particular protein they carry
2.6 Cytosis
2.6.1 movement of large amounts of substances into/out of the cells by folding of membranes
2.6.2 Endocytosis
2.6.2.1 taking substances into cell by infolding of cell membrane
2.6.2.1.1 for large molecules that cant fit through protein carriers or lots of molecules
2.6.2.2 removes part of cell membrane
2.6.2.3 Pinocytosis
2.6.2.3.1 takes in fluids
2.6.2.3.2 cell membrane invaginates and fluid droplets enter
2.6.2.3.2.1 membrane pinches off droplets
2.6.2.3.2.1.1 becomes a vesicle inside the cell
2.6.2.4 Phagocytosis
2.6.2.4.1 takes in large particles (food)
2.6.2.4.2 cell membrane flows out and around food particle
2.6.2.4.2.1 membrane outflowings (pseudopodia) meet and fuse, engulfing the food partiicle
2.6.2.4.2.1.1 becomes a food vacuole in cytoplasm
2.6.3 Exocytosis
2.6.3.1 removal of substances from cell
2.6.3.2 reverse of endocytosis
2.6.3.3 occurs when cells need to secrete a substance
2.6.3.4 adds to cell membrane
2.6.3.5 e.g. a hormone or salivary glands secreting amylase
3 CELL SIZE SHAPE AND DIFFUSION
3.1 cells have a dependency on diffusion for getting materials in/out of cell
3.1.1 therefore cells are tiny
3.2 as a cell grows, ratio b/w S.A : Vol decreases
3.2.1 i.e. less membrane for substances to diffuse through
3.2.1.1 diffusion gets less efficient
3.2.1.1.1 beyond a certain size, centre of cell doesnt recieve required substances
3.2.1.1.1.1 cell stops growing and divides to form 2 new smaller cells
3.3 cells increase S.A:Vol ratio by:
3.3.1 having an elongated shape
3.3.1.1 e.g. nerve cells, root hair cells
3.3.2 having a biconcave shape
3.3.2.1 e.g. RBC for efficient diffusion of oxygen
3.3.3 folding of cell membrane
3.3.3.1 e.g. microvilli- cells lining small intestine
3.4 greater rate of activity with high S.A : Vol ratio
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