Cell Transport

Maintaining Balance Homeostasis – process of maintaining the cell’s internal environment Cannot tolerate great change Boundary between cell and the environment What provides this?

Plasma Membrane Hydrophobic; Fatty Acid Tail Polar Head; Hydrophilic Fluid Mosaic Model Selective Permeability Phospholipid bilayer Hydrophobic; Fatty Acid Tail Polar Head; Hydrophilic

Cholesterol Provides stability Transport Proteins Carbohydrates Other Proteins Cell recognition (immune system)

Recall Following Terms Solution Diffusion Concentration gradient Results in uniform concentration

Osmosis Cells try to reach equilibrium Diffusion of water across a selectively permeable membrane; 3 results Isotonic Hypertonic Tonicity Hypotonic

Isotonic Solute concentration of solution equal to that of cell No net water movement

Hypertonic Solute concentration of solution higher than cell More dissolved particles outside of cell than inside of cell Hyper = more (think hyperactive); Tonic = dissolved particles Water moves out of cell into solution Cell shrinks

Hypotonic Solute concentration of solution lower than cell Less dissolved particles outside of cell Hypo = less, under (think hypodermic, hypothermia); Tonic = dissolved particles Water moves into cell from solution Cell expands (and may burst)

Active vs. Passive Active vs. Passive Transport Passive requires no energy from the cell Active requires cells to use energy, usually ATP

Passive Transport Have to move with the concentration gradient Diffusion Osmosis Facilitated Diffusion- involves use of transport proteins but still follow rule of diffusion

Active Transport Movement of materials against concentration gradient Transport proteins Endocytosis – cell takes in material Exocytosis – expulsion or secretion of materials from cell

Pinocytosis Phagocytosis