amp Movement Across Them Cell membrane channels Need to make doors through membrane protein channels allow substances in amp out specific channels allow specific material in amp out ID: 681470
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Slide1
2006-2007
Cell Membranes
&
Movement Across Them Slide2
Cell membrane channels
Need to make “doors” through membrane
protein channels allow substances in & out
specific channels allow specific material in & out
H
2O channel, salt channel, sugar channel, etc.
inside cell
outside cell
sugar
aa
H
2
O
salt
wasteSlide3
Diffusion
Move from
HIGH
to
LOW
concentration
directly through membranesimple diffusion
no energy neededhelp through a protein channel
facilitated diffusion (with help)no energy needed
HIGH
LOWSlide4
Active transport
Cells may need molecules to move
against
concentration “hill”
need to pump “uphill”
from
LOW to HIGH
using energyprotein pump
requires energyATP
ATPSlide5
Transport summary
simple
diffusion
facilitated
diffusion
active
transport
ATPSlide6
Keeping right amount of water in cell
Freshwater
a cell in
fresh water
high concentration of water around cell
cell gains water
example:
Paramecium problem: cells gain water,
swell & can burstwater continually enters Paramecium cell
solution: contractile vacuole
pumps water out of cell
freshwater
No problem,here
KABOOM
!
1Slide7
Keeping right amount of water in cell
Saltwater
a cell in
salt water
low concentration of water around cell
cell loses water
example: shellfish
problem: cell loses water
in plants: plasmolysisin animals: shrinking cell solution: take up water
saltwater
I will
survive
!
I’m shrinking,
I’m shrinking
!
2Slide8
Keeping right amount of water in cell
Balanced conditions
no difference in concentration of water between cell & environment
cell in equilibrium
example
:
blood
problem: nonewater flows across membrane equally,
in both directionsvolume of cell doesn’t change
balanced
I could
be better…
That’s
better
!
3