Osmosis, Diffusion & Membranes, oh my!

The Membrane * Label your diagram! We already know the cell membrane regulates what enters and leaves the cell, but what is it made of? Nearly all cell membranes are composed of a lipid bilayer (two layers of lipids)

The Membrane Each lipid is composed of two parts: * Label your diagram! Each lipid is composed of two parts: Hydrophilic Head (loves water) Hydrophobic Tail (hates water)

The Connection What does diffusion and osmosis have to do with the cell membrane? Diffusion and osmosis both involve the transport of substances across the cell membrane

Diffusion What is diffusion? When substances move from areas of high concentration (lots of particles) to low concentration (few particles).

Diffusion – Example 1

Diffusion – Example 2

Types of Diffusion There are two main types of diffusion: Passive: no energy is required because the particles are moving with the natural flow (from high concentration to low concentration)

Types of Diffusion Active: an input of energy is required because particles need to move against the natural flow

Visual Summary

Osmosis The movement of water across a membrane is an example of passive transport Osmosis: the diffusion of water across the cell membrane

Osmosis – Example 1

Osmosis – Example 2 Over Time Membrane Sugar Molecules

Summary On the Venn Diagrams on your notes, compare and contrast (1) active & passive transport and (2) osmosis & diffusion You should have at least 1 item in each of the three categories for both diagrams

Osmosis Recap Osmosis Video