Lab 19 - Osmotic Pressure and Growth

cytoplasm

site with the most important cellular functions within the bacterium

osmosis

water movement across a semipermeable membrane, based on the concentration of solutes

Hypertonic cell

the concentration of solutes are higher outside the cell; water leaves the cell; cells shrinks

plasmolysis

cells “shrinking” due to hypertonicity; makes it difficult for the cell to carry out essential functions

hypotonic cells

the concentration of solutes are higher inside the cell; water enters the cell; cell swells

isotonic cells

equilibrium of solutes; water exits and enters cell at same pace

turgor pressure

pressure required by bacteria to sustain life; created by the influx of water into a bacterial cell; bacteria store or import ions to maintain pressure

turgor pressure effect on eukaryotic cell

tend to burst with too much pressure

what limits bacteria from bursting in hypotonic solutions?

peptidoglycan cell wall

halophiles

can grow at higher salt concentrations due to the ability to maintain high enough cytoplasmic contractions of solutes; prevent loss of water at over 3% NaCl

facultative halophile

can grow at high-salt and low-salt concentrations

obligate halophile

can only grow at high-salt concentrations

1%, 3%, 7%, and 11%

the different salt concentrations of the tubes

results

higher absorbance number indicates higher bacterial numbers and better growth