Types of Cellular Transport

Passive Transport

cell doesn’t use energy1. Diffusion2. Facilitated Diffusion3. Osmosis

Active Transportcell does use energy

1. Protein Pumps2. Endocytosis3. Exocytosis

high

low

This is gonna

be hard work!!

high

low

Weeee!!!

2

Facilitated Diffusion

*Is a type of passive transport

• Doesn’t require energy

• Uses transport proteins to move molecules from high to low concentration

Examples: Glucose or amino acids moving from blood into a cell.

• Facilitated Diffusion is the movement of larger molecules like glucose through the cell membrane – larger molecules must be “helped”

Proteins in the cell membrane form channels for large molecules to pass through

Proteins that form channels (pores) are called protein channels

outside of cell

inside of cell

Glucose molecules

Facilitated Diffusion

Facilitated diffusion

• Molecules move from high to low through a protein channel

• No energy is needed

5

Active Transport

Requires energy or ATP

Moves materials from LOW to HIGH concentration

AGAINST concentration gradient

6

Active transport

Examples: Pumping Na+ (sodium ions) out and K+ (potassium ions) in against strong concentration gradients.

Called Na+-K+ Pump

Active TransportActive transport is the movement of molecules from LOW to HIGH concentration.

Energy is required as molecules must be pumped against the concentration gradient.

Proteins that work as pumps are called protein pumps.

Ex: Body cells must pump carbon dioxide out into the surrounding blood vessels to be carried to the lungs for exhale. Blood vessels are high in carbon dioxide compared to the cells, so energy is required to move the carbon dioxide across the cell membrane from LOW to HIGH concentration.

outside of cell

inside of cell

Carbon Dioxide molecules

NO ENERGY NEEDED: Diffusion Osmosis Facilitated Diffusion

ENERGY NEEDED: Active Transport

ANALOGY:

Compare the types of transport

Food is moved into the cell by Endocytosis

Wastes are moved out of the cell by Exocytosis

• Endocytosis and Exocytosis is the mechanism by which very large molecules (such as food and wastes) get into and out of the cell

• **ENERGY IS REQUIRED

13

Moving the “Big Stuff”

Molecules are moved out of the cell by vesicles that fuse with the plasma membrane.

Exocytosis- moving

things out.

This is how many hormones are secreted and how nerve cells communicate with one another.

14

ExocytosisExocytosis vesicle immediately after fusion with plasma membrane.

15

Endocytosis – Phagocytosis

Used to engulf large particles such as food, bacteria, etc. into vesicles

Called “Cell Eating”

Ex: White Blood Cells, which are part of the immune system, surround and engulf bacteria by endocytosis.