1. Membrane Structure and Transport

2. Membrane Structure Phospholipid bilayer (nonpolar)
Membrane proteins – act as transport channels
Carbohydrate chains –act as “ID” tags for the cell
Cholesterol – provides stability for the membrane

3. Fluid Mosaic Model
5/the-fluid-mosaic-model/

4. Membrane Functions
Provides a selectively permeable barrier around the cell
Controls the passage of substances in and out of the cell.
Polar and charged substances can pass through the membrane proteins (“gates”)
Maintains homeostasis for the cell helping it meet its needs.

5. Types of Cellular Transport
ACTIVE
Requires energy from ATP
Goes against the concentration gradient (low to high)
Active Transport, Endocytosis, Exocytosis
PASSIVE
Does not require energy
Goes with the concentration gradient (high to low)
Simple Diffusion, Osmosis, Facilitated Diffusion

6. Passive Transport: Simple Diffusion
hill.com/sites/ /student_view0/chapter 2/
Simple diffusion is when a small, 
non-polar molecule passes through a lipid bilayer.  
.

7. Passive Transport: Osmosis
Osmosis is the diffusion of water through a selectively permeable membrane.
Water will move to the side of the membrane that has the higher solute concentration.

8. Osmosis (Cont.)
Cells will shrivel when put into a solution with MORE SOLUTE. Ex) salt water
If solute concentration is equal on both sides of the membrane, the cell does not change.
Cells will swell or burst when put into a solution with LESS SOLUTE Ex) Fresh water

9. Tonicity

10. Passive Transport: Facilitated Diffusion
Particles are moving through a transport protein from high to low concentration
Particles that are polar are charged must move through a protein channel
Glucose and ions enter the cell in this way.

11. Facilitated diffusion Hypertonic Hypotonic Isotonic
Vocabulary
Lipid bilayer
Passive Transport
Diffusion
Osmosis
Facilitated diffusion
Hypertonic
Hypotonic
Isotonic

12. Active Transport
Particles move from low to high concentration against concentration gradient
Requires ATP energy
The sodium / potassium pump is an example.

13. Active Transport: Endocytosis
The plasma membrane surrounds and brings large particles into the cell
Phagocytosis – cell “eating”
Pinocytosis – cell “drinking”
Requires energy

14. Active transport: Exocytosis
The export of large particles such as waste out of the cell
Proteins, hormones, and other substances are secreted from cells in this manner
Nerve cells release neurotransmitters in this manner

15. Vocabulary
Active Transport
Endocytosis
Exocytosis