this is a review of the structure and function of the cell membrane

1. The Cell Membrane
The Key to Cellular Transport

2. Characteristics of the Cell
Membrane
 Made of phospholipids
– arranged in two layers called a bilayer
 Selectively permeable
-it controls “selects” what can enter or leave the cell
-some materials are allowed through others aren’t
 Fluid Mosaic Model
- made of different molecules – phospholipids, proteins,
cholesterol
- the molecules aren’t static but can move “fluid”

3. Lipid bi-layer – the heart of the
membrane
 Phospholipids are arranged into 2 layers
- called a bilayer

4. Phospholipids: Phosphate Heads
 Polar/hydrophillic – attracted to water and
charged particles

5. Phospholipids: Lipid Tails
 Nonpolar/hydrophobic – repel water and
charged particles

6. Cholesterol
 Found in bilayer – helps to hold the membrane together
while adding to fluidity of the membrane

7. Glycoproteins
 Proteins with carbohydrates attached – identifies the cell
type
-allows it to bind with other cells of the same type

8. Receptor Proteins
 recognize and bind with substances outside of the cell,
causing changes inside the cell

9. Enzymes
 Allow reactions to occur- light reactions and ETS occur
with enzymes in membrane

10. Transport Proteins
 Proteins that extend across the membrane – provide a
way for large or charged molecules to cross the
membrane

11. Types of Transport Proteins
 Ion Channels- allow certain charged particles to cross
the membrane – passive transport
 Carrier Proteins – bind to a specific molecule and carry it
across the membrane
- facilitated diffusion – proteins carry molecules with
the concentration gradient /no cellular energy is
required
- active transport – proteins carry molecules against
the concentration gradient/ cellular energy is required