Movement Through Cell Membrane

1
Movement Through Cell Membrane
2
4 Ways Movement Occurs

• Diffusion
• Osmosis
• Facilitated diffusion
• Active transport

3
Diffusion

• Movement from high to low concentration.
• No energy used.
• Net movement until equilibrium.

4
Osmosis

• Diffusion of H2O through permeable membrane.
• Cell membranes permeable to H2O.
• Water moves to dilute.

5
Types of Solutions

• Hypertonic higher concentration above
  strength.
• Hypotonic lower concentration below
  strength.
• Isotonic same concentration same strength.

6
Osmotic Pressure

• Movement of water toward hypertonic side of
  membrane.
• Cells have to deal with this.

7
Dealing with Osmotic Pressure

• Isotonic surroundings blood.
• Cell wall.
• Pumps contractile vacuole in paramecium.

8
Facilitated Diffusion

• Move compounds that are impermeable.
• Through special channels.
• Glucose moves a/c blood cell membrane through
  protein channels.

9
Characteristics of F.D.

• Specific
• Fast
• Does not require energy

10
Active Transport

• Movement of substance from low to high
  concentration.
• Moves against concentration gradient.
• Cell has to use energy.

11
Types of Active Transport

• Sodium-potassium pump overcomes diffusion.
• Many ions diffuse easily, but cells need to
  maintain concentration gradient.

12
Types of A.T. (Cont.)

• Endocytosis cell membrane has pockets to trap
  material, forms vacuole.
• Phagocytosis large particles, membrane
  surrounds them.
• Pinnocytosis water.

13
Exocytosis

• Reverse of endocytosis, gets rid of waste or cell
  products.