1

2

3

Topic name 4

Diffusion Molecules move from an area of higher concentration to an area of lower concentration What causes diffusion? –Random motion of molecules Water Dissolved molecules 5

Diffusion Molecules in solution tend to slowly spread apart over time. This is diffusion. 6

Diffusion concentrated, high energy molecules [High] [Low] diffuse, low energy molecules 7

3 types of diffusion 1. Simple Diffusion Some very small, non-polar molecules, including oxygen and carbon dioxide, can pass directly through the cell membrane in a process called simple diffusion. 8

2. Channel Diffusion Proteins in the membrane provide a gateway for diffusion. When molecules move down a concentration gradient through an open protein pore, the process is called channel diffusion. 3. Facilitated Diffusion While channel proteins are a simple open door, carrier proteins are more complex. In a process called facilitated diffusion. 9

Why diffusion is important ? All living things have certain requirements they must satisfy in order to remain alive. This tasks happen at the cellular level. Molecules move through the cell membrane by diffusion. 10

Continue…. Uptake of minerals is also affected by the process of diffusion. It helps in removal of excess water of transpiration. It is an essential process of gases during respiration and photosynthesis. 11

Characteristic of diffusion It occur in solid, liquid and gases It does not require any semi- permeable membrane. All time does not require water. Passive and external energy is needed. 12

Diffusion in physics Diffusion in solids was used long before the theory of diffusion was created. It is produces steel from the element iron (Fe) through carbon diffusion. In modern science Thomas Graham studied diffusion in gases and phenomenon was described by him 13

Example At first, the particles are all near one top corner of the glass. If the particles randomly move around in the water, they eventually become distributed randomly and uniformly from an area of high concentration to an area of low concentration. 14

Some other examples A sugar cube is left in a beaker of water in a while. Fumes of the perfume rises from the bottle when the top is removed. Food coloring on the beaker causing to spread out. Adding of sugar in water. 15

16

17