Passive and Active Transport

The cell membrane

cell membrane = semi-permeable

​what is semi-permeable (selectively permeable)

The cell membrane allows some substances to pass in and out of the cell easily, but other substances cannot. Some substances require "helpers" such as protein channels to get through the cell membrane.

Poll

Which of these analogies do you like best to help thinking of the cell membrane as selectively permeable?

• A bouncer at the club

• A gate to a fenced in yard

• Gandalf from "Lord of The Rings" saying "YOU SHALL NOT PASS"

PHOSPHOLIPID BILAYER: 2 layers of phospholipids arranged together, with embedded proteins

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The Cell Membrane

Labeling

Label the phospholipids and the proteins in the cell membrane image.

Drag labels to their correct position on the image

Phospholipids

Proteins

Passive transport

• The movement of molecules from high concentration to lower concentration without the use of energy

Passive Transport

• Movement of substance across plasma membrane WITHOUT any energy

Multiple Choice

Does passive transport require energy?

• Yes

• No

Passive Transport #1 Diffusion

Movement of molecules from high concentration to low concentration.

Stops when equilibrium is reached

Simple Diffusion

Molecules move from high concentration to low concentration through a membrane

Multiple Choice

How do molecules move during diffusion?

• From high concentration to low concentration

• From low concentration to high concentration

Equilibrium

Molecules are equally spread out

Multiple Choice

What is the goal of diffusion called when molecules are equally spread out?

• Sameness

• Equilibrium

Passive Transport #2 Osmosis

Water molecules move from high concentration to low concentration through a membrane

Multiple Choice

What type of molecules are moving during osmosis?

• Salt

• Sugar

• Water

Passive Transport #3 Facilitated Diffusion

Molecules move from high to low concentration through a PROTEIN

Does not require energy!

Uses a "helper" (protein)

Multiple Choice

Does facilitated diffusion, which uses helper proteins, require energy?

• Yes

• No

Remember:

Passive Transport is how molecules move across a cell membrane WITHOUT any energy

There are 3 types of passive transport...

1) Diffusion - moves "stuff"

2) Osmosis - moves "water"

3) Facilitated diffusion - moves "stuff" using helpers

Cell Transport

Active Transport

Cell transport that REQUIRES ENERGY

Active Transport

• Movement of materials through a membrane against a concentration gradient

• Movement of substances from areas of low concentration to areas of high concentrations

• Requires: ENERGY from the cell (ATP), and a transport protein or channel protein (these are often called pumps)

Multiple Choice

Which direction does ACTIVE TRANSPORT move materials?

• From high to low concentration

• From low to high concentration

Transport of Ions

• Transport of ions: Protein pumps move ions across membranes

• Example: Sodium-Potassium Pump

Transport of Large Particles

• Move across the membrane by endocytosis or exocytosis

Endocytosis - brings materials in to cell

• Cell membrane folds in around a large particle and forms a small pouch

• The pouch then "pinches off" from the cell membrane to become a vesicle inside the cell

• Phagocytosis: cell eating (engulfs food particles)

• Pinocytosis: cell drinking (engulfs fluid)

Exocytosis - pushes materials out of cell

• A vesicle moves to the cell membrane

• Fuses with cell membrane, and then releases its contents to the outside of the cell.

Match

Match the following

• Endocytosis

• Exocytosis

• Active Transport

• Transport of ions

Brings materials in to the cell

Pushes materials out of cell

Movement of molecules using energy

Uses protein pumps

• Brings materials in to the cell

• Pushes materials out of cell

• Movement of molecules using energy

• Uses protein pumps

SUMMARY OF CELL TRANSPORT

QUICK QUIZ!

Multiple Choice

In PASSIVE TRANSPORT, substances move from:

• High concentration to low concentration

• Low concentration to high concentration

Multiple Choice

True or False: In simple diffusion, molecules move from high concentration to low concentration across a membrane.

• True

• False

Multiple Choice

In ACTIVE TRANSPORT, substances move from:

• High concentration to low concentration

• Low concentration to high concentration

Multiple Choice

True or False:

In ACTIVE TRANSPORT, energy is not required.

• True

• False

Multiple Choice

True or False:

In PASSIVE TRANSPORT, energy is required.

• True

• False

Multiple Choice

Which type of diffusion uses a protein to help molecules get across?

• Simple diffusion

• Facilitated diffusion

Multiple Select

Check all the examples of PASSIVE transport

• Diffusion

• Endocytosis

• Facilitated diffusion

• Exocytosis

• Osmosis

Multiple Select

Check all the examples of ACTIVE transport.

• Protein Pumps

• Endocytosis

• Exocytosis

• Osmosis

• Facilitated diffusion