CELLULAR TRANSPORT CELL MEMBRANE All cells have cell

CELLULAR TRANSPORT

CELL MEMBRANE All cells have cell membranes The functions of the cell membrane are →Controls what enters and exits the cell to maintain an internal balance called homeostasis →Provides protection and support for the cell

STRUCTURE OF CELL MEMBRANE Lipid bilayer = 2 layers of phospholipids Phospholipids have a hydrophilic head and a hydrophobic tail Hydrophilic = water loving Hydrophobic = water fearing

Cell Membrane

CELL MEMBRANE & TRANSPORT Cell membranes are selectively permeable: it allows some molecules in and keeps other molecules out The structure of the cell membrane helps it be selective Molecules in motion have kinetic energy

TYPES OF CELLULAR TRANSPORT PASSIVE TRANSPORT Cell does not use energy ACTIVE TRANSPORT Cell has to use energy DIFFUSION PROTEIN PUMPS FACILITATED DIFFUSION ENDOCYTOSIS OSMOSIS EXOCYTOSIS

PASSIVE TRANSPORT Cell uses NO energy Molecules move randomly Molecules go from an area of HIGH concentration to LOW concentration 3 types : diffusion, facilitated diffusion, osmosis

1. DIFFUSION Diffusion: random movement of particles from an area of high conc. to an area of low conc. Diffusion continues until all molecules are evenly spaced (equilibrium is reached) Molecules will still move around but stay spread out

Animation 1. DIFFUSION

2. FACILITATED DIFFUSION Diffusion of specific particles through transport proteins found in the membrane Transport Proteins are specific – they “select” only certain molecules to cross the membrane Also goes down a concentration gradient (HIGH → LOW)

Animation 2. FACILITATED DIFFUSION

3. OSMOSIS Diffusion of water through a selectively permeable membrane Many molecules dissolve in water Molecule is the solute Water is a solvent Osmosis is diffusion of water from high concentration to low concentration

Animation 3. OSMOSIS SALT SUCKS!

TYPES OF SOLUTIONS HYPERTONIC SOLUTION ISOTONIC SOLUTION HYPOTONIC SOLUTION

1. HYPERTONIC The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. OUTSIDE CELL: High solute/Low water Water goes from inside the cell to outside Cell SHRINKS

2. ISOTONIC The solution has an equal concentration inside and outside the cell. Water moves equally in both directions Cell stays the same size

3. HYPOTONIC The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. OUTSIDE CELL: Low solute/High water Water goes from solution into the cell Cell SWELLS & BURSTS

TYPES OF SOLUTIONS

ACTIVE TRANSPORT Cell has to use energy Happens AGAINST a concentration gradient Molecules go from LOW concentration to HIGH concentration Difference between active and passive transport is the direction of movement

1. PROTEIN PUMPS Transport proteins that require energy (ATP) move the molecules in and out Example: Sodium/Potassium Pumps

1. PROTEIN PUMPS

2. ENDOCYTOSIS Transporting Uses bulky material into a cell energy Cell membrane in-folds around food particle “Cell Eating” Forms food vacuole & digests food This is how white blood cells eat bacteria!

2. ENDOCYTOSIS PHAGOCYTOSIS PINOCYTOSIS

ACTIVE VS PASSIVE TRANSPORT