Chapter 8: Cellular Transport and the Cell Cycle

There are two types of cellular transport: I. Passive Transport - particles move from high to low concentration; CELL ENERGY IS NOT REQUIRED!

II. Active Transport – moves particles from low to high concentration; CELL ENERGY IS REQUIRED NOTE: There is a greater concen-tration of particles inside the cell than outside the cell Click in box to play movie

Types of passive transport A. DIFFUSION the random motion of particles from an area of high concentration to an area of low concentration until dynamic equilibrium is reached.

1. Diffusion of water – Osmosis sugar semi permeable membrane On the left side of the membrane the concentration of water is greater than the concentration of sugar. Water moves via osmosis to the other side of the U-tube.

Concentration gradient 2. Facilitated diffusion – with a concentration gradient, carrier proteins move materials across the plasma membrane. Carrier Proteins Concentration gradient Plasma membrane

3. Filtration – pressure gradient pushes solute-containing fluid through a membrane from higher pressure area to lower pressure area. Coffee pot works this way Kidneys also work this way

II. Types of active transport A. endocytosis – material is engulfed and enclosed by the plasma membrane and brought into the cell Types of endocytosis: 1. pinocytosis – bringing in liquids 2. phagocytosis – bringing in solids

A second type of active transport: B. exocytosis – getting rid of large particles Wastes Digestion Exocytosis Endocytosis

A solution is a mixture in which one or more Review A solution is a mixture in which one or more substances are distributed evenly in another substance. sweet tea solute – what gets dissolved (sugar) solvent – what does the dissolving (water)

How a cell reacts in types of solutions: Isotonic Solution (iso – same) concentrations of solute and solvent are the same inside and outside a cell or membrane no net movement

cell will swell Hypotonic Solution (hypo – below, solute concentration is lower in solution than in cell, solvent concentration is higher in solution) solvent (water) will move into the cell cell will swell

cell will shrink Hypertonic Solution (hyper – above, concentration of solute is greater in solution, solvent concentration is lower) solvent (water) will move out of cell cell will shrink