Transcript Diffusion and Osmosis

 Video from Youtube on Diffusion and osmosis –
www.youtube.com/watch?v=AYNwynwaALo
Homeostasis
 Steady state
 Balance an organism maintains by self regulating
adjustments
 Example: Body Temperature and Heart Rate (blood
Flow supply o2 and nutrients)
DIFFUSION
 Process by which molecules spread due to their
random movement from an area of high concentration
to low concentration
 Example: when you spray lysol
CONCENTRATION GRADIENT
 Difference in concentration of a substance in a given
area
 MOLECULES move naturally from high concentration
to low concentration until equilibrium is reached.
 Equilibrium means balance or homeostasis
Three Ways to increase rate of diffusion:
 concentration
 increase pressure
 Heat (makes molecules move faster)
Cell Membrane – regulate molecules – the flow of
materials in and out of the cell
 Permeable – if substance passes through it is
permeable to that substance
 Selectively permeable – only allows some substance
through
Solution – a mixture of one or more substances dissolved
in it
 Solvent – water
 Solute – salt
Idea: kool aid – water is the solvent and the packet of
mix is the solute
THREE TYPES OF SOLUTIONS:
 Hypotonic solution – concentration of solutes in the
environment lower than in the cell (H2O moves in)
 Hypertonic – concentration of solutes in the
environment is higher than in cell (H2O moves out)
 Isotonic solution – equal concentration of solute in cell
and environment ( h20 in and out equally) Maintains
equilibrium or homeostasis
Type of Solutions
Type of
Solutions
If
the
con
cent
ratio
n of
solu
te
(salt
) is
equ
al
on
both
side
s,
the
wat
er
will
mov
e
back
in
fort
h
but
it
won
't
hav
e
any
resu
lt on
the
over
all
amo
unt
of
wat
er
on
eith
er
side.
"IS
O"
mea
ns
the
sam
e
The
wor
d
"HY
PO"
mea
ns
less,
in
this
case
ther
e
are
less
solu
te
(salt
)
mol
ecul
es
outs
ide
the
cell,
sinc
e
salt
suck
s,
wat
er
will
mov
e
into
the
cell.
The
cell
will
gain
wat
er
and
gro
w
larg
er.
In
plan
t
cells
, the
cent
ral
vac
uole
s
will
fill
and
the
plan
t
beco
mes
stiff
and
rigid
, the
cell
wall
keep
s
the
plan
t
from
burs
ting
In
ani
mal
cells
, the
cell
may
be
in
dan
ger
of
burs
ting,
orga
nell
es
calle
d
CO
NT
RAC
TIL
E
VAC
UO
LES
will
pum
p
wat
er
out
of
the
cell
to
prev
ent
this.
The
wor
d
"HY
PER
"
mea
ns
mor
e, in
this
case
ther
e
are
mor
e
solu
te
(salt
)
mol
ecul
es
outs
ide
the
cell,
whi
ch
caus
es
the
wat
er to
be
suck
ed
in
that
dire
ctio
n.
In
plan
t
cells
, the
cent
ral
vac
uole
loses
wat
er
and
the
cells
shri
nk,
caus
ing
wilti
ng.
In
ani
mal
cells
, the
cells
also
shri
nk.
In
both
case
s,
the
cell
may
die.
This
is
why
it is
dan
gero
us
to
drin
k
sea
wat
er its a
myt
h
that
drin
king
sea
wat
er
will
caus
e
you
to
go
insa
ne,
but
peop
le
mar
oon
ed
at
sea
will
spee
d up
deh
ydra
tion
(an
d
deat
h)
by
drin
king
sea
wat
er.
This
is
also
why
"salt
ing
field
s"
was
a
com
mon
tacti
c
duri
ng
war,
it
wou
ld
kill
the
crop
s in
the
field
,
thus
caus
ing
food
shor
tage
s.
Isotonic Solution – equal concentration of solute in cell
and environment (H2O in and out equally)
Osmosis – diffusion of water from areas of greater
concentration to lesser concentration
Turgor pressure – as water diffuses into a plant cell it
exerts a force against the cell wall
 Plasmolysis – cell shrink
 Cytolysis – cell bursts
 Contractile vacuole – some single cell animals in the
water use this to pump out the excess water
 Passive transport – movement across a membrane
without use of energy (Diffusion and Osmosis)
 Active Transport – movement across a membrane with
energy
 Carrier Molecule – proteins which function in
transport
a. Facilitate diffusion – uses a carrier molecule to speed
up diffusion but does not use energy
Example: Glucose needs insulin to speed diffusion
into cell
b. Active transport – uses carrier molecules to go
against concentration gradient. Uses energy.
MOVEMENT OF LARGE MOLECULES
 Endocytosis (endo – in)process by which cells engulf
substances which are too large to diffuse through the
cell membrane
a. Phagocytosis – food
b. Pinocytosis – liquid
Example: ameba white blood cells
 Exocytosis ( exo-out) movement of large molecules out
of the cell
Example: wastes
Active and Passive Transport
 video on transport and endocytosisi
Review of Terms:
 A difference in concentration creates a concentration gradient
 Prefix that means “inside” is endo
 A word that means “cell” – cyto
 Prefix that means “outside” – exo
 Active transport will remove sodium ions, while taking in
potassium ions
 Channel proteins can help move things across the membrane
 Organelle that helps remove excess water; contractile vacuole
 The outer boundary of the cell is the membrane