Osmosis

Molecules that can diffuse through the cell membrane:

• Steroids (because they are lipid-soluble)

• Uncharged (neutral) molecules

• Small molecules

Molecules that cannot diffuse across membrane:

• Ions (charged molecules)!!!!!

• Large molecules

Temperature and Molecular weight affects diffusion rate:

• Cooler water temperature slows diffusion (molecules move slower)

• Warmer water temperature speeds up diffusion (molecules move faster)

• Heavy molecules diffuse more slowly

Diffusion:

• Solutes move from high concentration to low concentration until equilibrium is reached

• Diffusion does not require energy (ATP) — it is passive

• Water is a universal solvent

Osmosis is the movement of water 

• Which way is the water moving (in or out of the cell)? 

  • Osmosis in kidneys (hypertonic environment, hypotonic environment, isotonic environment)

  • Osmosis in plant cells (hypertonic environment, hypotonic environment, isotonic environment)

  • Red blood cells in saline (hypertonic environment, hypotonic environment, isotonic environment)

Active transport needs energy from the cell

Hemolysis is when Red Blood Cells are placed in a hypotonic environment and water moves into the cells causing them to burst

Plasmolysis is when Plant cells are placed in a hypertonic environment and water moves out of the cell causing them to shrink