Osmosis. Transport mechanisms Passive transport (doesnt require energy) Diffusion Facilitated...
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Transcript of Osmosis. Transport mechanisms Passive transport (doesnt require energy) Diffusion Facilitated...
Osmosis
Transport mechanisms
Passive transport (doesn’t require energy) Diffusion Facilitated diffusion Osmosis Filtration
Active transport (uses energy from ATP)Active transportBulk transport
} Movement down a concentration gradient
3. OsmosisDiffusion of water molecules
through a selectively permeable membrane,
from an area of high water potential
to an area of low water potential
NB: Water potential gradient is opposite to solute concentration gradient.
High water potential = low solute concentration
Concentration Gradient
Water Potential Gradient
Membrane is impermeable to large sugar moleculesbut permeable to small water molecules
Selectively permeable membrane
H2O
Why is OSMOSIS important for living organisms?
• Osmo-regulation - maintaining the right levels of water in cells is vital for life.
• HOMEOSTASIS – maintain balance / equilibrium
• Water moves between cells in a multi-cellular organism
Water balance
COPY
Passive transport
• http://www.youtube.com/watch?v=sdiJtDRJQEc&feature=related (osmosis, 1 min)
• http://www.youtube.com/watch?v=JShwXBWGMyY (passive transport, 5 min)
Transport mechanisms
Passive transport (doesn’t require energy) Diffusion Facilitated diffusion Osmosis Filtration
Active transport (uses energy from ATP)Active transportBulk transport
} Movement down a concentration gradient
2. Active transport
• Uses chemical energy from ATP
• Move molecules against the concentration gradient (low conc. high conc.)
Tonicity is a relative term
• Hypotonic Solution - lower concentration than another solution
• Hypertonic Solution - higher concentration than another solution
• Isotonic Solution - both solutions have same concentration
Shriveled
TurgidFlaccidPlasmolysed
Normal Lysed
HYPOTONICISOTONICHYPERTONIC
ANIMAL CELL
PLANTCELL
ISOTONIC HYPERTONIC HYPOTONIC
NORMAL EXPANDEDSHRIVELED