1. KEY CONCEPT The cell membrane is a barrier that separates a cell from the external environment.

2. Cell membranes are composed of two phospholipid layers.

3. Cell membranes are composed of two phospholipid layers.
The cell membrane has two major functions.
cell membrane

4. Cell membranes are composed of two phospholipid layers.
The cell membrane has two major functions.
forms a boundary between inside and outside of the cell
cell membrane
outside cell
inside cell

5. Cell membranes are composed of two phospholipid layers.
The cell membrane has two major functions.
forms a boundary between inside and outside of the cell
controls passage of materials in and out of the cell
cell membrane
outside cell
inside cell

6. Cell membranes are composed of two phospholipid layers.

7. Cell membranes are composed of two phospholipid layers.
The cell membrane is made of a phospholipid bilayer.
cell membrane

8. Cell membranes are composed of two phospholipid layers.
The cell membrane is made of a phospholipid bilayer.
There are other molecules embedded in the membrane.
cell membrane
protein
cholesterol
carbohydrate
chain
protein channel

9. Cell membranes are composed of two phospholipid layers.
The cell membrane is made of a phospholipid bilayer.
There are other molecules embedded in the membrane.
Charged phosphate group, glycerol, and two fatty acid chains; heads are polar and form hydrogen bonds with water;
tail non-polar.
cell membrane
protein
cholesterol
carbohydrate
chain
protein channel

10. Cell membranes are composed of two phospholipid layers.
The fluid mosaic model describes the membrane.
Membrane is flexible like a fluid and has a variety of molecules like the variety of tiles in a mosaic

11. Cell membranes are composed of two phospholipid layers.
The cell membrane is selectively permeable.
Some molecules can cross the membrane while others cannot.

12. Cell membranes are composed of two phospholipid layers.
The cell membrane is selectively permeable.
Some molecules can cross the membrane while others cannot.

13. Chemical signals are transmitted across the cell membrane.
Receptors bind with ligands and change shape. Detect signal molecule and perform an action in response.
There are two types of receptors.

14. Chemical signals are transmitted across the cell membrane.
Receptors bind with ligands and change shape.
. Detect signal molecule and perform an action in response.
There are two types of receptors.
intracellular receptor:
Located inside a cell:
bind to molecules that can
Cross membrane

15. Chemical signals are transmitted across the cell membrane.
Receptors bind with ligands and change shape.
There are two types of receptors.
intracellular receptor
membrane receptor:
located in the membrane
binds to molecules that
cannot cross the
membrane, transport
message inside the
cell