1. Cell Membrane Objectives
Summarize the main functions of a cell membrane.
List and illustrate the main structures of a cell membrane, in terms of phospholipids, proteins and carbohydrates.
Compare and contrast cell membranes to cell walls.

2. Cell Membrane A cell membrane has 3 main functions Functions
Controls what enters / exits cell.
Protects cell.
Supports cells.
Cell membrane surrounds cell.

3. Cell Membrane A cell membrane is made of 3 types of organic molecules
Structure
Phospholipid bilayer
Proteins (integral and peripheral)
Carbohydrates

4. Cell Membrane Phospholipid bilayer
Most of a cell membrane is made of a phospholipid bilayer
Double layer of phospholipid molecules.
Fluid and flexible.
Allows some small, non-polar molecules through, but blocks large or charged molecules.

5. Cell Membrane Phospholipid molecules have a “head” and a “tail”
Phospholipid molecules arrange themselves into bilayer because of their special structure. H O
Hydrophilic head “loves” water.
Hydrophobic tail “fears” water.

6. Cell Membrane Integral and peripheral proteins
Proteins are attached to phospholipid bilayer and perform many functions:
Integral proteins are attached to membrane. They can transport materials or carry signals in and out of the cell.
Peripheral proteins temporarily attach to phospholipid bilayer or integral proteins.

7. Cell Membrane Carbohydrates
Some carbohydrate chains are attached to the membrane surface. These help cells identify and recognize each other.

8. Cell Membrane Cell Wall
A cell wall is a hard, flexible extra layer surrounding the cell membrane in some organisms, including:
Plants
Fungi
Some bacteria

9. Exit Ticket 1. Summarize the main functions of a cell membrane.
The main functions of a cell membrane include…
2. List and illustrate the main structures of a cell membrane, in terms of phospholipids, proteins and carbohydrates.
The main structures of a cell membrane includes…
Illustration of cell membrane: …
3. Compare and contrast cell membranes to cell walls.
In comparison, a cell membrane and cell wall both _______________________. In contrast, a cell membrane is _____________________________________________, while a cell wall is ___________________________________________________________.