BSC 2010 L osmosis/diffusion and organic macromolecules

osmosis

the movement of a solvent, such as water, through a semi-permeable membrane.

semipermeable membrane

A thin barrier between two solutions that permits only certain components of the solutions, usually the solvent, to pass through

osmotic pressure

the pressure needed to prevent osmosis from occurring. pressure builds up on the side of the membrane where volume has increased. Ultimately, this pressure prevents more water from entering (for example, the bag in, and osmosis stops

which way does osmosis move a solvent

from less concentrated solution to a more concentrated solution

solute concentration

solute/solvent

how does water move through plant cells through osmosis

Solute concentrations increase going from soil to root cells to leaf cells. The resulting differences of osmotic pressure help to push water upward. Osmosis also controls the evaporation of water from leaves by regulating the size of the openings (stomata) in the leaves' surfaces.

concentration

The quantity of solute (for example sugar) dissolved in a given volume of solution (for example water).

hypertonic solution

 A solution with a higher osmotic pressure (solute concentration) than another solution

hypotonic soln

A solution with a lower osmotic pressure (solute concentration) than another solution.

isotonic

Two solutions that have the same concentration of solute particles and therefore the same osmotic pressure

solute

A substance dissolved to make a solution, for example sugar in sugar water.

solution

A mixture of two or more substances that appears to be uniform throughout except on a molecular level

solvent

The major component of a solution or the liquid in which some other component is dissolved, for example water in sugar water.

does preserving food w salt involve hypertonic, hypotonic, or isotonic conditions?

hypertonic bc the high salt concentration kills bacteria through dehydration

how do artificial kidneys involve dialysis

salts and other molecules move out of blood into a surrounding tank of distilled water. Red blood cells are too large to pass through the dialyzing membrane, so they return to the patient's body

how does desalination work with reverse osmosis

Salt can be removed by placing seawater in contact with a semipermeable membrane, then subjecting it to great pressure. Under these conditions, reverse osmosis occurs, by which pressure is used to push water from a more concentrated solution to a less concentrated solution. pushes water molecules out of seawater into a reservoir of pure water.

tonicity

the relative concentration of solute on either side of a membrane

how do hypotonic soln affect animal cells

the cells can lyse (rupture) due to the osmotic pressure.

how do hypotonic soln affect plant cells

The cell wall these cells prevents the cell from rupturing. The osmotic pressure, called turgor pressure, helps support the cell

cell that is turgid meaning

A cell in which the contents are under pressure

how do hypertonic soln affect plant cells

will undergo plasmolysis, a condition where the plasma membrane pulls away from the cell wall as the cell shrinks. The cell wall is rigid and does not shrink.

how do hypertonic soln affect animal cells

will undergo crenation, a condition where the cell shrivels up as it loses water.

plasmolysis

 the shrinking of the cytoplasm of a cell in response to diffusion of water out of the cell. This may occur when cells are placed in a solution containing a high concentration of solutes

diffusion

the movement of molecules from a region of high concentration to one of low concentration

what reagent do u use to test for carbohydrates and what colors should it be?

benedict’s soln and you boil the soln in hot water for a few minutes, Orange, Brick-Red to Brown Precipitate for positive, light blue for negative. for chemstrips, they turn from yellow to green in the presence of glucose, negative: stays yellow

what reagent do u use to test for polysaccharide/starch and what colors should it be?

iodine, positive: dark-purple, blue-black negative: amber/yellow and performed at room temp.

what reagent do u use to test for proteins and what colors should it be?

biuret reagent, positive: purple negative: light blue and requires alkaline conditions

what reagent do u use to test for lipids/non-polar fats and what colors should it be?

sudan dye test- positive: red layer negative: non-translucent spot performed in water

dry paper test- positive: persistent translucent spot, negative: evaporated water mark.

Which macromolecule are the dark granules within the potato cells composed of?  [Hint – What caused the iodine to turn dark?]

amylose (starch)