Cell Transport Betsy Sanford 7 th Grade Life

Cell Transport Betsy Sanford 7 th Grade Life Science

Cell Transport • Cells need to obtain materials such as food, oxygen and water for growth, development, and repair • Cells need to remove wastes like excess water and carbon dioxide from chemical activities

Cell Membrane • Selectively permeable (semi-permeable, porous, has holes) • Allows materials to pass in and out of the cell • Helps cell maintain internal balance (homeostasis) • Fluid Mosaic Model

Passive Transport • No energy needed • Happens automatically due to the natural motion of molecules • Molecules move from high concentrations to low concentrations

Passive Transport • Moving toward equal distribution of molecules in a space • Molecules will move until the available space is evenly filled (balanced) • 2 types: diffusion and osmosis

Diffusion • Any type of molecule (solid, liquid, gas) • Molecules move from areas of high density to areas of low density • Example: the molecules of the spilled perfume spreading throughout a room • Brain. POP – Diffusion

Osmosis • Always and only the movement of water molecules across a cell membrane • Water may be moving into the cell or out of the cell to achieve balance with the surrounding environment

Osmosis in Red Blood Cells 1. Distilled (pure) water on the outside. Cells are not pure water. Water will move into the cell until the cell bursts. 2. Normal red blood cells have a balance of water on the inside with the environment on the outside. 3. When red blood cells are placed in salt water, water will exit the cell to balance with the environment. Cells will shrink.

Active Transport • Energy is needed to move molecules • Molecules are being moved to areas that are already concentrated • Like trying to add more to an overstuffed suitcase • 2 types: endocytosis and exocytosis

Endocytosis • The use of energy to move materials into the cell • Endo = enter

Exocytosis • The use of energy to move materials out of the cell • Exo = exit

Cell Transport • Brain. POP – Passive Transport • Brain. POP - Active Transport • Amoeba Sisters’ Cell Transport