Transcript If you put two liquids or gases next to each other, even

If you put two liquids or gases next to each
other, even if they are totally still they will
mix with one another slowly
Cell membrane; just passing
through!
• http://www.teachersdomain.org/resources/td
c02/sci/life/cell/membraneweb/assets/tdc02_
int_membraneweb/tdc02_int_membraneweb
_swf.html
• Animation of cell transport through
membrane.
Diffusion
• the molecules that make it up are
bouncing around.
• The hotter, the more bouncing.
• over time the molecules bounce around
and mix.
Diffusion
• This mixing is very slow and takes a long
time, but if you leave the two gases
next to each other for long enough they
will mix perfectly.
• This effect is called diffusion and is
why balloons go down slowly and how
oxygen gets from your blood into your
cells among many other processes.
• http://www.chaosscience.org.uk/pub/public_
html//article.php?story=20050301222247333
Osmosis
• http://zoology.okstate.edu/zoo_lrc/biol1114/t
utorials/Flash/Osmosis_Animation.htm
• Two containers of
equal volume are
separated by a
membrane
• that allows free
passage of water,
• but totally restricts
passage of solute
molecules
• water flow through a semi-permeable
membrane that blocks the transport of salts or
other solutes through it.
• The key to remember about osmosis is that
water flows from the solution with the lower
solute concentration into the solution with
higher solute concentration
Osmosis
• reason it is important is that all living cells
are covered with these materials which will
let water through but not salt or sugars
• if you stay in a bath too long water moves into
your skin and your fingers go all wrinkly
• if you go swimming in the sea and get covered
with salt, you get really thirsty as the water
is sucked out of you by the salt and osmosis
The Three Little Cranberries
In order to remember the different states important in osmosis, consider
the following "fairytale":
The first little cranberry, named Hypertonic, stayed out in the sun too long.
He lost all the water from inside his little red body and became shrunken
and wrinkled. His body became plasmolyzed.
The second little cranberry, named Hypotonic, fell asleep soaking in the hottub. When he woke up his body had absorbed a lot of water and he was fat
and his skin was very tight, ready to burst. His body became turgid.
The third little cranberry, Isotonic, was smart. He stayed inside all day and
studied his science textbook. His body remained flaccid.
This isn't an exact match to what happens in osmosis, but it will give you a
visual hook to remember the results on a cell immersed in each type of
medium.
•
Osmosis
The natural tendency for water to spontaneously
pass through a semipermeable membrane
separating two solutions of different concentrations
(strengths). The water will naturally pass from the
weaker (less concentrated) solution containing fewer
particles of dissolved substance to the stronger (more
concentrated) solution containing more particles of a
dissolved substance. The natural osmosis causes the
stronger solution to become more diluted, and tends
to equalize the strength of the solutions on both sides
of the membrane.