1. What elements make up proteins?
Objective: ASWDTAT differentiate between active and passive transport as well as describe how most small molecules cross the cell membrane.
KEY TERMS
Selectively permeable diffusion osmosis
Passive transport active transport
DO NOW
What elements make up proteins?

2. The Cell Membrane
The cell membrane is selectively permeable, which means that some substances can pass through the membrane while others cannot.
Cells let in needed materials such as oxygen and food molecules.

3. Diffusion
Diffusion is the main method by which small molecules move across the cell membrane
The process by which molecules move from an area of higher concentration to an area of lower concentration.
Concentration is the amount of the substance in a given volume.

4. What causes diffusion?
Since molecules are always moving, they are bumping into each other and then moving away from one another.
An example would be like an air freshener.

5. Osmosis
Osmosis is the diffusion of water molecules through a selectively permeable membrane.
Because cells cannot function properly without water, many cellular processes depend on osmosis.
Water moves from an area of high concentration to an area of low concentration.

7. Transport
The movement of dissolved materials through a cell membrane without using cellular energy is called passive transport.
Active transport is the movement of materials through a cell membrane using cellular energy.

8. Recap What causes diffusion? What is osmosis? What is semipermeable?
What is the difference between active and passive transport?

9. Homework
Pg 30 #1-3, Pg 37 #1-5
Vocabulary quiz tomorrow