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plasma membrane is.....
selectively permeable
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movement of substances from one area to depends on
concentration gradient
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Passive transport:
requires NO ATP to move down concentration gradient--Passive processes - substances move across cell membranes without the input of any energy; uses the kinetic energy of individual molecules or ions
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Active transport:
requires ATP to move against a concentration gradient--Active processes - a cell uses energy, primarily from the breakdown of ATP, to move a substance across the membrane, i.e., against a concentration gradient
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3 methods of cell transports
what are they?
- GENERAL TRANSFER
- CARRIER MEDIATED TRANSFER
- osmosis
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general transfer
e g: filtration& simple diffusion, & Osmosis which is flow of water across a membrane living or non living are all
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CARRIER MEDIATED TRANSFER, uses 2 tyopes of protein carriers to transfer across cell membrane what are they ?
- facilitated diffusion--is carrier mediated, but passive transport..eg glucose which attaches itself to carriers to be transported across the PM
- Carrier mediated Active transport---is carrier mediated to go up a gradient and needs ATP so is Active transport
- 1)Ion Pump eg sodium/potassium pump
- 2)E.g.vesicular transport :Exocytosis, phagocytosis, pinocytosis)
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Movement of particles through a selectively permeable membrane by hydrostatic pressure
Examples
filtration of nutrients from blood capillaries into tissue fluids
filtration of wastes from the blood in the kidneys
filtration (passive)
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Net movement of particles from area of high concentration to area of low concentration
due to their constant, random motion Also known as movement down the concentration gradient
simple diffusion (passive)
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Rate of Diffusion
1-Steepness of concentration gradient- ↑difference, ↑ rate
2-Temperature-- ↑ temp., ↑ motion of particles
3-Mass of diffusing substance--- larger molecules move slower
4-Surface area-↑ area, ↑ rate
5-membrane permeability -- ↑ permeability, ↑ rate
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Net movement of water through a selectively permeable membrane from an area of high concentration of water (lower concentration of solutes) to one of lower concentration of water
Water can pass through plasma membrane in 2 ways:
1.through lipid bilayer by simple diffusion
2.through aquaporins, integral membrane proteins
osmosis
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what are aquaporins?
channel proteins specialized for osmosis!
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