D2.3 - Water Potential

solvation

process of dissolving - solving molecules interact with solute molecules

• hydrophobic substances dissolve non-polar

• hydrophilic in polar substances

solvent molecules

liquids which dissolve other substances

solute molecules

dissolved substances in solutions

water is a good solvent due to

its DIPOLAR nature - forms hydrogen bonds to dissolve substances

osmolarity

measure of concentration of a solute

isotonic

same solute concentration than to another

hypertonic

higher solute concentration than to another

hypotonic

lower solute concentration than to another

concentration is measured in

moles

osmosis

movement of water from an area of high to low water potential

osmosis when osmolaric changes

• Isotonic - nothing changes

• Hypertonic - cell loses water

• Hypotonic - gains water, can rupture

Water movement cell without a cell wall

when lacking a cell wall

• hypotonic - water enters cell, it bursts - develops tugor pressure

• hypertonic - water exits cell, shrinkage, crenation, plasmolysis, wilts

  • plasmolysis: shrinkage of a cells cytoplasm

• isotonic - remains equilibrium = no net movement of water

contractile vacuole

maintains osmotic balance in freshwater organisms

movement in cells with a cell wall

• hypotonic: water moves into cell by osmosis, vacuole fills up → cytoplasm pushes against cell wall which creates TUGOR PRESSURE and makes cell rigid

• hypertonic - 1. water moves out the cell by osmosis, 2. cytoplasm and vacuole shrink → pulls membrane from the cell wall, 3. plasmolysis (shrinkage of cytoplasm) occurs due to water loss

Isotonic solution in medical procedures

• eye drops

• organ transplants

human cells + water potential

• isotonic - water molecules pass through the plasma membrane = cell remains healthy

• hypotonic - cell swells/ bursts

• hypertonic - cell dehydrates