Summary
Summary AQA ALEVEL BIOLOGY NOTES ON DIFFUSION AS LEVEL
- Module
- Unit 2 - Cells
- Institution
- AQA
ALEVEL NOTES ON THE CELL TRANSPORT TOPIC- DIFFUSION ADJUSTED TO THE AQA SPECIFICATION AND MADE FROM MARKSCHEMES
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Diffusion =Diffusion the of from highly
is net movement molecules ions region where
they are more
-
or a
concentrated to one where their concentration is lower until distributed
evenly .
I T
A BB00
-
Diffusion
' I. Simple ( lipid diffusion )
000
'
I /
"" ← to x
|
I L
Simple diffusion when diffuse cell
f- is
particles across
.
- -
- - - - . .
can
>
I membranes without the help of transport proteins .
4) ,
Fick 's law Rate of diffusion =
Cone .
diff X Surface area
diffusion distance
Dynamic Equilibrium
dynamic
'
.
in
' high concentration equilibrium
gradient faster
' - -
- - - - - - -
n
,
'
.
I
\
Inside outside Inside outside
low concentration dynamic
equilibrium
-
gradient - - - - - .
- - -
-
n
,
-
-
-
slower
>
Inside outside Inside outside
§
'
2 Facilitated Diffusion
.
I
, T
Facilitated diffusion is diffusion proteins and channels
using protein
•
carrier .
•
The
transport tend to be specific for molecule
proteins one
,
so substances can
only cross a
membrane that contains an
appropriate protein .
This diffusion inbuilt kinetic of
is the the
diffusing molecules
•
passive process only
a it relies on
energy
-
.
There is no external input of ATP from respiration .
end
channel hydrophilic
t.IM?isnsdeinngse.smi%ae
proteins
channels
-
They form
and
water
allow
-
filled
specific
hydrophilic
water-soluble ions
If \ If If
[ \ If If \ \ If If \ If If
through
/
to
pass
/
.
The bind with the protein it
ions
causing
-
NOI channel
to conformational hydrophobic -
gated Gated channel
carry change .
end
[ BI9
Carrier proteins
→
4"
{ /
When such specific
-
a molecule as glucose
to the protein
Conformational
is present ,
it binds
that
with
the
protein .
If If If If If If If If If \ \ If \ If
change occurs
-
released
1
molecule is inside of the membrane
↳
.
kinetic of
Only molecules drive
changed site
-
the
energy process .
binding
•
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