Chapter 7-3 in textbook Cell Transport maintaining homeostasis

Cell Membrane Regulates what enters and leaves the cell Cell membrane is surrounded by water Phospholipid bilayer

Cell Membrane Lipid bilayer Forms by itself in water Proteins attached Markers Receptors Transport channels

Diffusion in cells When small molecules diffuse in and out of the cell to reach equilibrium on both side of the membrane

Passive Transport Does NOT require any ATP or energy Happens automatically Channels may be used in cell membrane

Passive Transport This type of transport moves from an area of high concentration to low concentration

Diffusion Type of passive transport When molecules move from an area of higher concentration to an area of lower concentration until equilibrium is met

Concentration The amount of dissolved solute in a solution Molecules will move to an area less concentrated Molecules diffuse through the cell membrane of cells

Concentration gradient The difference in concentration in a solution between a cell and its surroundings

Concentration Gradient No gradient - even distribution Concentration to the right

Increase Rate of Diffusion Temperature Molecules move faster in higher temperatures Pressure Increasing pressure also increases rate of diffusion

Equilibrium This occurs when there is no longer a concentration gradient Molecules are evenly dispersed but still continue to move randomly

Osmosis Diffusion of water across a biological membrane From an area of high concentration to low concentration of WATER Comparing concentrations

Osmosis in Cells Cells are surrounded by water and filled with water Water can move freely through the membrane

Direction of Osmosis

Osmotic Pressure Net movement of water into cells Determined by solute concentration

Osmosis - hypertonic Higher concentration of solute in solution Ex: a cell in salt water If molecules are too large to fit through cell membrane or protein channels Water will diffuse OUT of the cell to reach equilibrium Cell shrinks

Osmosis - hypotonic Lower concentration of solute in solution Ex: a cell in pure water If molecules are too large to fit through cell membrane or protein channels Water will diffuse INTO the cell to reach equilibrium Cell swells - may burst!

Osmosis - Isotonic Equal concentration in solution If molecules are too large to fit through cell membrane or protein channels Water will diffuse IN AND OUT of the cell to maintain equilibrium

Red Onion Cells - Isotonic

Red Onion Cells - Hypertonic

Red Onion Cells - Hypotonic

Facilitated Diffusion When the cell membrane has protein channels (carrier proteins) where materials are transported in or out of cell NO energy needed for this process  

Active Transport Against concentration gradient From an area of low concentration to an area of high concentration Requires cell energy ( ATP ) because you’re going AGAINST concentration gradient

Active Transport Protein channels embedded in cell membrane Gated channels Need energy to open Protein changes shape when energy is used

Sodium/Potassium Pump Step 1: 3 Na+ ions bind to carrier protein Step 2: ATP binds to carrier protein and changes shape allowing Na+ to move out of the cell Step 3: 2 K+ ions move into carrier protein Step 4: ATP binds to carrier protein and changes shape allowing K+ to move into the cell

Sodium/Potassium Pump

Sodium Potassium Pump

You used to transfer Potassium…

Movement in Vesicles Endocytosis - INTO the cell Cell membrane is used to create a vesicle around particles Phagocytosis Particle ingestion Pinocytosis Liquid ingestion

Movement in Vesicles Exocytosis - OUT of the cell Vesicles created in the cell fuse with cell membrane and release particles/liquids Known as bulk transport