Cellular%20Transport

1
Cellular Transport

• The movement of materials in and out of cells
• Ch 8

2
Cellular Transport

• What substances move ?
• How do they move?
• What is the membrane structure?
• What is passive versus active transport?

3
Solution Concentration

• Like density
• molecules per
• volume of container
• Low or High Concentration

High Conc.

Low Conc.
4
Diffusion

• Movement of molecules
• gas or liquid
• Law of Diffusion
• From High Concentration to
• Low Concentration

5
Diffusion of gases.
O2 High
CO2
CO2 High
6
Cell Membrane

• Surrounds cells
• Gives shape to animal cells
• Inside cell wall of plant cells

7
Cell Membrane

• Made of
• Lipid layer
• Protein channels
• Semi-permeable

8
Cell Membrane
9
Semi-permeable

• Semi some substances may pass
• Selective
• Based upon size solubility

H20 flows
Salt remains
10
Osmosis

• Movement of water
• Across a semi-permeable membrane
• Special case of diffusion

11
Equilibrium
H2O H2O H2O H2O H2O H2O H2O
H2O H2O

• Equi Equal concentrations
• On both sides of membrane
• Osmosis stops
• Isotonic Solution

12
In Osmosis.only H2O moves

• Therefore focus on the water concentration
• 1 Salt solution
• Water is
• High concentration
• Salt is Low

• 10 Salt Solution
• Water is
• Low
• concentration
• Salt is High

13
Osmosis in cells

• 10 salt solution
• -H20
• NaCl

1 salt solution H20 -NaCl
H20
H20
Water flows from High to Low Concentration
14
Active or Passive Transport?

• Which requires ATP energy?
• Which goes with the concentration gradient?
• Which goes against the gradient?

15
Concentration Gradient


16
Passive Transport

• Diffusion or Osmosis
• Going with the gradient
• No ATP energy required

High Conc. To Low Conc.



17
Active Transport

• Against the gradient
• Requires ATP
• Low to High Concentrations
• Salt returning to blood in kidneys

18
Plasmolysis

• Cell membranes shrink or expand
• Dependent on salt concen-trations

19
Hypotonic or Hypertonic Solutions?
Tap Water

• Hypotonic under or low salt outside, relative
  to cell
• Hypertonic over or high salt relative to cell

Salt water inside cell
20
Sea water organism in fresh water.
Tap Water

• Hypotonic Solution
• Low salt concentration outside the cell
• High Water concentration outside
• Water moves?
• Inside
• Cell Bursts!

• Salt Water
• Inside Cell
• Low Water

H20
21
Fresh water organismin salt water.

• Hypertonic Solution
• Water moves?
• Out of the cell
• Cell shrinks

• Salt Water
• High salt
• Low water

• Fresh water
• Inside cell
• High Water

H20
22
Plants cells bulge, not burst!
Or Cell Membranes Shrink
23
Paramecium have water pumps!(called contractile
vacuoles)