Unit 3: Movement In and Out of Cells

Diffusion

Movement of molecules from a region of high concentration to a region of low concentration down the concentration gradient

Factors influencing diffusion rate

• Larger concentration gradient

• High temperature

• Large surface area

• Distance

Osmosis

Movement of water molecules from a region of high water potential to a region of low water potential through a partially permeable membrane

Isotonic Solution

Concentration of solute = concentration inside cell → no change in size

Hypertonic Solution

Concentration of solute outside cell > concentration inside cell → (plants) Cytoplasm shrinks from cell wall, (animals) Cell shrinks

Hypotonic solution

Concentration of solute outside cell < concentration inside cell: (plants) Turgid cell, (animals) Cells swell and burst

Active Transport

Movement of particles through a cell membrane via a protein transporter from a region of lower concentration to a region of higher concentration against a concentration gradient using energy released from respiration.