cell transport the movement of molecules can be either passive (no energy) or active (needs energy)...
TRANSCRIPT
Cell Transport
The movement of molecules can be either passive (no energy) or active (needs energy)
depending upon the membrane structure and concentration gradients.
AS Biology, Cell membranes and Transport 2
Transport through cell membranes
AS Biology, Cell membranes and Transport
3
Transport through cell membranes
• The cell membrane is a good barrier around cells, especially to water soluble molecules. However, for the cell to survive some materials need to be able to enter and leave the cell.
• There are 3 basic mechanisms:
1. DIFFUSION
2. OSMOSIS
3. ACTIVE TRANSPORT
AS Biology, Cell membranes and Transport
4
Diffusion of liquids
AS Biology, Cell membranes and Transport 5
• Diffusion is the net movement of molecules (or ions) from a region of their high concentration to a region of their lower concentration.
The molecules move down a concentration gradient.
Molecules have kinetic energy, which makes them move about randomly.
As a result of diffusion molecules reach an equilibrium where they are evenly spread out.This is when there is no net movement of molecules from either side.
AS Biology, Cell membranes and Transport
6
DIFFUSION
Diffusion is a PASSIVE process which means no energy is used to make the molecules move.
AS Biology, Cell membranes and Transport
7
Diffusion through a membrane
Observe the molecules moving from a region of high to low. Cell membrane
Inside cell Outside cell
AS Biology, Cell membranes and Transport
8
Diffusion through a membrane
Cell membrane
Inside cell Outside cell
diffusion
AS Biology, Cell membranes and Transport
9
Diffusion through a membrane
Cell membrane
Inside cell Outside cell
EQUILIBRIUM
AS Biology, Cell membranes and Transport
10
AS Biology, Cell membranes and Transport
11
AS Biology, Cell membranes and Transport 12
Molecules that diffuse through cell membranes
1. Oxygen – so diffuses very quickly.
2. Carbon dioxide – very small so diffuses quickly.
3. Water – very small so diffuses quickly.
AS Biology, Cell membranes and Transport
13
Osmosis
‘The diffusion of water from an area of high concentration of water molecules to an area of low concentration of water across a semi permeable membrane.’
AS Biology, Cell membranes and Transport
14
Osmosis
Cell membrane partially permeable.
Inside cell Outside cellVERY High conc. of water molecules. High water potential.
VERY Low conc. of water molecules. High water potential.
Sugar molecule
DILUTE SOLUTIONCONCENTRATED SOLUTION
AS Biology, Cell membranes and Transport
15
Osmosis
Cell membrane partially permeable.
Inside cell Outside cellHigh conc. of water molecules. High water potential.
Low conc. of water molecules. High water potential.
OSMOSIS
AS Biology, Cell membranes and Transport
16
Osmosis
Cell membrane partially permeable.
Inside cell Outside cell
OSMOSIS
EQUILIBRIUM. Equal water concentration on each side. Equal water potential has been reached. There is no net movement of water
AS Biology, Cell membranes and Transport
17
Red Blood Cell Placed in both salt water and distilled water.
AS Biology, Cell membranes and Transport
18
Look what happens to plant cells in both salt water and distilled water!
AS Biology, Cell membranes and Transport
19
AS Biology, Cell membranes and Transport
20
AS Biology, Cell membranes and Transport
21
AS Biology, Cell membranes and Transport
22
AS Biology, Cell membranes and Transport
23
Receptor Proteins These proteins are used in intercellular communication. In this animation you can see the a hormone
binding to the receptor. This causes the receptor protein release a signal to perform some action.
• Found on surface• Detects hormones• Acts as binding site on Cell Membrane