1. 7.2 The Plasma Membrane
Main Idea: The plasma membrane helps to maintain homeostasis in the cell

2. Function of the Plasma Membrane
The process of maintaining an organisms internal environment is homeostasis
The plasma membrane is primarily responsible for maintaining homeostasis

3. Plasma Membrane
Thin flexible boundary between a cell and its environment
Allows nutrients into the cell and waste and other products to leave the cell

4. Selective Permeability
The plasma membrane allows some substances to pass through and keeps others out

5. Structure of the Plasma Membrane
The plasma membrane is made of a phospholipid bilayer
This is 2 layers of phospholipids arranged tail to tail

6. Structure of the Plasma Membrane
The heads of the phospholipids are hydrophilic
They like water
The tails are hydrophobic
They hate water

7. Structure of the Plasma Membrane
The hydrophobic lipids do not allow water soluble substances to cross easily
This helps keep the environment outside and inside the cell separate

8. Other components of the plasma membrane
Proteins are found in 3 places in the plasma membrane
Outside the cell
Receptors- transmit signals to the inside of the cell
Inside the cell
Anchor the membrane to the inner support structure
Gives the cell its shape
Spanning the membrane
Moves substances through the membrane

9. Other components of the plasma membrane
Cholesterol
Prevents the phospholipid bilayer from sticking together
Carbohydrates
Helps to identify chemical signals