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methods of transport, potential - Coggle Diagram
methods of transport
active transport
movemet of molecules from a lower concentration to a higher concentration , against a concentration gradient
- the cell uses carrier proteins to pump substances across the membrane
- process requires expenditure of energy in form of ATP ( molecule produced by respiration in mitochondria)
used in many processes
- uptake of glucose & amino acids in small intesines
- excretion of hydrogen ions & urea by kidneys
exchange of sodium & potassium ions in neutrons and muscle cells
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diffusion
movement of molecules from an area of high concentration to an area of low concentration down a concentration gradient
molecules posses kinetic energy which keeps them moving so they can be passively transported across biological membranes
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osmosis
- diffusion of water
- net movement of water molecules from region of high water concentration to a region of low water concentration through a partially permeable membrane
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bulk transport
extremely large substances need to be moved across a cell membrane , bulk is used
2 types
endocytosis
- bulk transport of material into the cell
- split into 3 processes, phagocytosis, pinocytosis, receptor-mediates endocytosis
exocytosis
bulk transport of materials out of the cell
- the reverse of endocytosis
lipid based molecules
fat soluble molecules e.g. steroid hormones can pass through phospholipid membrane BECAUSE bilayer=fatty acid tails
- they diffuse down conc grad through membrane -> cell
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potential
water potential
- net movement of water by osmosis is determined by differences in water potential between 2 solutions connected by a partially permeable membrane
- it is the tendency of water molecules in a system to move.
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- measures in kilopascals (kPa)
- highest water potential = pure water = 0 kPa
- water molecule always move from a region of high water potential to a region of low (more negative) water potential
solute potential
- the water potential of a solution is affected by the amount of solute it contains
- the greater the amount of solute, the lower the water potential
water molecules bind to solute somecules reducing the number of water molecules that are free to diffuse
contribution that solute make to the water potential of a solution is the solute potential (Ψs) and is - value
pressure potential
- water potential of solution is affected by the pressure applied to it
- the greater the pressure, the higher the water potential
- pressure potential (Ψp) = always + value
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