maintaining homeostasis Cell Transport maintaining homeostasis Chapter 5 in textbook

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

What affects the rate of diffusion? Concentration of the solution Temperature of the solution Pressure also speeds up particle motion

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 Concentration Gradient

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

Cell Membrane Movement through membrane Cell membrane is surrounded by water Phospholipid bilayer

Cell Membrane Forms by itself in water Proteins imbedded Markers Receptors Channels

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

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

Hypertonic Outside cell is more concentrated than cell ex: 20% salt solution 10% salt solution The solution with 20% salt is hypertonic compared to the 10% salt solution

Hypotonic Outside the cell is less concentrated than cell ex: 10% salt solution 20% salt solution The solution with 10% salt is hypotonic compared to the 20% salt solution

Isotonic Equal concentrations ex: 10% salt solution 10% salt solution Equilibrium is reached

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

Osmosis - hypertonic Higher concentration 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 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

Osmosis in Plant Cells Turgor Pressure Pressure on the walls of the plant cells due to vacuole filling Increase in turgor pressure is increase in water to cell Plasmolysis When a cell shrinks due to lack of water

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

3 types of 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

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