d.2 water potential

what is water known as?

the universal solvent

solvation

the combination of a solvent with the molecules or ions of a solute

properties of water

a partial negative charge at the oxygen and partial positive charge at the hydrogen pole

positively charged ions are attracted to ...

the partial negative oxygen pole of water

negatively charged ions are attracted to ...

partial positive hydrogen pole of water

three steps to solvation

1. Separation of Solute Particles
2. Separation of Solvent (water) Molecules
3. separated solute and water particles combine to make a solution

osmosis

the net movement across a membrane to the side that has a higher concentration of solutions

cells in a hypertonic environment

surrounded by a solution that is higher in solutes and lower water relative to the cytoplasm inside the cell membrane

cells in a hypotonic environment

surrounded by a solution that is lower in solutes and higher in water relative to the cytoplasm inside the cell membrane

cells in an isotonic environment

has equal concentrations of solute inside and outside the cell

what happens when cells are placed in a hypertonic solution without a cell wall

water moves out of the cell - visibly shrinks resulting in crenation

what happens when cells are placed in a hypotonic solution

water moves into the cell resulting in swelling

contractile vacuole

organelle that collects excess water in the cytoplasm and expels it from the cell; prevents cell from bursting and swelling when in a hypotonic environment

when do humans most commonly experience the effects of cell shrinkage

dehydration - can lead to organ shrinkage and lightheadedness

why are bacterial and plant cells less vulnerable to effects of osmosis

they have a cell wall, which is a solid with a high tensile strength

hydrostatic pressure

the pressure a fluid exerts in a confined space, against the boundary of the space

what is hydrostatic pressure called in plant cells

turgor pressure

turgor pressure

incoming water swells the cell and presses the cell membrane against the rigid cell wall
- maintains the plant's shape and stay upright

plasmolysis

cytoplasm shrinkage in plants

plant cells in hypotonic solutions are called

turgid (swollen)

plants cells in hypertonic solutions are called

flaccid (limp)

why are isotonic solutions important

in medical procedures they keep human tissues osmotically stable and healthy

isotonic example: contant lenses

kept in a isotonic saline solution that is compatible with the eye tissue

isotonic example: IV soltions

most are isotonic so that they do not cause excess water movement in and out of the body cells

isotonic example: organ transplants

organs are immersed in isotonic solution before it is transplanted to avoid any cell damage