Download How cells exchange materials

How cells exchange
materials
To Osmosis and beyond!
The cell membrane


phospholipid bilayer - 2 thin layers of
phospholipids with proteins.
The membrane controls the passage
of materials in and out of the cell.
Plasma Membrane made of
phospholipids


Fatty acids tails – hydrophobic
Glycophosphate heads – hydrophilic
Membrane is a fluid mosaic

Phospholipids and proteins “float” around
each other
Cholesterol

Helps Maintains membrane rigidity, not too
fluid
Membrane Proteins



Part of membrane structure and function
Integral proteins are within membrane
Transmembrane proteins – integral
proteins that go from one side to other.
Aid in passage of materials.
Freeze fracture technique

Freezing and fracturing membrane allows
for showing integral membrane proteins
Peripheral proteins

Proteins on surface. Not part of membrane
structure.
Glycoproteins and glycolipids

Act as cell surface markers. Identify cell
Membrane Protein functions
1) Selective transport
channel
2) Enzyme
3) Cell surface receptor
4) Cell surface identity
marker
5) Cell to cell adhesion
6) Attachment to
cytoskeleton
CELL TRANSPORT
Active and passive transport

Active transport – Requires energy
Passive transport – occurs with out energy
supplied

Active and passive transport

Diffusion

Movement of materials from an area
of high concentration to an area of
low concentration
Diffusion
Diffusion across a membrane
Concentration gradient


The difference between the area of
high and low concentration
Net flow- diffusion is random both
ways. Net flow always high to low
Osmosis
Diffusion of water through a membrane to
maintain salt/solute balance
Water potential = osmotic potential energy
Osmotic pressure


Pressure that must be applied to prevent
osmosis through a membrane
Reverse osmosis is greater pressure
forcing water against osmotic gradient
Osmoregulation

Living organisms use osmotic pressure
against osmotic gradient, to maintain
water balance
Isotonic Solution


Water on both sides of cell membrane is
the same
equilibrium
Iso means Same

Isosceles
Saline is isotonic
Isotonic solutions have same
molarity

Example cell with salt. There will be NO
change in mass of cell
Hypertonic solution


Solution has MORE salt than cell
Water moves out
Hypotonic


Solution has LESS Salt than the cell
Water moves IN
Blood cells
Why does water spray on the
produce at ShopRite?
Solution cell placed in
Hypotonic
Animal Cell
Plant Cell
Isotonic
Hypertonic
Solution cell placed in
Hypotonic
Animal Cell Lysed (bad)
Plant Cell
Isotonic
Hypertonic
Solution cell placed in
Animal Cell
Plant Cell
Hypotonic
Isotonic
Lysed (bad)
Normal
(good)
Hypertonic
Solution cell placed in
Animal Cell
Plant Cell
Hypotonic
Isotonic
Hypertonic
Lysed (bad)
Normal
(good)
Shriveled
(bad)
Solution cell placed in
Hypotonic
Isotonic
Hypertonic
Animal Cell
Lysed (bad)
Normal
(good)
Shriveled
(bad)
Plant Cell
Turgid (good)
Solution cell placed in
Hypotonic
Isotonic
Hypertonic
Animal Cell
Lysed (bad)
Normal
(good)
Shriveled
(bad)
Plant Cell
Turgid (good) Flaccid (bad)
Solution cell placed in
Animal Cell
Plant Cell
Hypotonic
Isotonic
Hypertonic
Lysed (bad)
Normal
(good)
Shriveled
(bad)
Turgid (good) Flaccid (bad)
Plasmolyzed
(bad)
Graphing molarity
Make best fit line of data
 What does green line show?
Isotonic concentration
= 2.2 M

Passive transport

Diffusion through a cell membrane
without any energy added.
Facilitated diffusion


Proteins help with normal diffusion, act as
channels
Passive – goes with concentration gradient
Active transport

Proteins use energy to transport
through a membrane against a
concentration gradient.
Like a salmon swimming upstream
Protein pumps

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Sodium potassium pump – against gradient
http://highered.mcgrawhill.com/sites/0072495855/student_view0/c
hapter2/animation__how_the_sodium_pota
ssium_pump_works.html
Endocytosis

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in/cell
A cell folds around a large molecule
to bring it in.
Requires ATP
Ex. Amoeba
Receptor mediated endocytosis

Protein receptors attach to specific
particles to activate endocytosis
Phagocytosis


Phage = eat
When large particles are taken in by
Endocytosis by amoeba or white blood
cells
Pinocytosis

Taking in water or small particles by
endocytosis
Exocytosis

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Out/cell
Removal of large molecules out of cell by
vessilce merging with membrane

The End