2-10: osmotic pressure

- little solute, lots of water

- movement water into the cell

define hypotonic/hyposmotic

equal solute to water concentration

define isotonic/isosmotic

- lots of solute, little water

- movement of water out of the cell

define hypertonic/hyperosmotic

- internal pressure against the cell wall

- species of bacteria and archaea require water to maintain the cellular turgor pressure

- prevents shrinking of the cytoplasm and the associated separation of the cytoplasmic membrane from the cell wall (prevents plasmolysis)

define turgor pressure

- plants, algae, cyanobacteria (anything with a chloroplast organelle)

- they use the water molecules as e- donors for the linear e- flow (want inside to be hypertonic and outside to be hypotonic so water constantly moving in)

name 3 organisms that execute oxygenic photosynthesis via linear electron flow and relate this to turgor pressure

- silica (glass) cell wall

- fit together in two halves like a box

describe the cell wall structure of diatoms (domain eukarya, autotrophs)

- PM detaches from cell wall due to efflux of water (hypertonic environment)

- proteins are not hydrated/dissolved causing them to mis-shape, which causes no function to be carried out

- bacterial static

define plasmolysis

- cell wall breaks down due to influx of water (hypotonic environment)

- bacterial cytol

define osmotic lysis (lysis by osmotic pressure)

no; the cell wall of the microbe would have to be structurally broken or weak for some reason in order for lysis to take full effect and kill

are microbes frequently at risk for cell-lysis

the net diffusion of water (using aquaporins in the PM)

define osmosis (be able to predict or illustrate the direction of net water movement if given various tonicity examples)

thrive under salty conditions

define halophiles

require a specific salt concentration for growth

define obligate halophiles

requires 15%-25% salinity (will not grow outside of this range)

define extreme halophiles

can tolerate the presence of salinity up until a certain salt concentration

define facultative halophiles

Staphylococcus spp. and Escherichia coli (UPEC strain)

give 2 examples of facultative halophiles

a measure of how well a cell (microbe) can handle a wide range of osmotic pressures

define osmotolerance

thrives at low salinity (>3%) like most microbes

describe the classification of E. coli K-12 (symbiotic/commensalistic)

- halotolerant (osmotolerant)

- can grow in absence or presence of salt up to about 7.5% NaCl

describe the classification of Staphylococcus epidermidis (and pretty much all other Staphylococcus spp.)

it is the basis of the mannitol salt agar media as a selective/differential media for Staphylococcus spp.

what is the importance of Staphylococcus spp. being halotolerant

- extreme halophile

- San Fransisco salt farms have tons of this microbe thriving in it

describe the classification of Halobacterium salinarum (domain archaea)

- plasmolysis can cause cytosolic proteins that normally have hydration shells to not have enough water to form the hydration shells (inside is hypotonic and outside is hypertonic)

- proteins will then precipitate out of water and won't be able to shape change, losing their function

- bacterial static!

relate osmotic pressure to the shapes of a specific microbial species' proteins and enzymes (hint: hydration shells dissolve proteins in order to shape change - function)