Anatomy and Physiology Cell Transport

Types of Transport Diffusion Characteristics –Particles move from an area of high concentration to an area of low concentration. –Moves “down” or “with” the concentration gradient. (difference in concentration) –Does not require energy.

Types of Transport Factors effecting the rate of diffusion –Temperature –Temperature - as temperature increase, rate of diffusion increases. –Pressure –Pressure - as pressure increases, rate of diffusion increases. –Steepness of the concentration gradient - –Steepness of the concentration gradient - the steeper the gradient, the faster the rate of diffusion.

Types of Transport Diffusion will continue until dynamic equilibrium is reached. Dynamic equilibrium -Dynamic equilibrium - continuous movement of particles, but no overall concentration change. (Everything is equally distributed).

Type of Transport Osmosis Characteristics –Movement of water across a cell membrane. –Cell has no control over movement of water. It continues to move until [inside] = [outside]. [ ] =concentration

AS Biology, Cell membranes and Transport 6 Osmosis Cell membrane partially permeable. Inside cell Outside cell VERY High concentration of water molecules. VERY Low concentration of water molecules. Sugar molecule DILUTE SOLUTION CONCENTRATED SOLUTION

AS Biology, Cell membranes and Transport 7 Osmosis Cell membrane partially permeable. Inside cell Outside cell High conc. of water molecules. Low conc. of water molecules. OSMOSIS

AS Biology, Cell membranes and Transport 8 Osmosis Cell membrane partially permeable. Inside cell Outside cell OSMOSIS EQUILIBRIUM. Equal water concentration on each side. Equal water potential has been reached. There is no net movement of water – water moves in and out of cell at the same rate.

What is a solution? 2 Parts: Solvent – Usually a liquid like water Solute – Usually a solid such as sugar, salt

Isotonic Solution Isotonic: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell. ISO = THE SAME Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium) Osmosis Animations for isotonic, hypertonic, and hypotonic solutionsOsmosis

Osmosis - Types of Solutions Isotonic [water inside] = [water outside] Dynamic equilibrium reached immediately. Normal Red blood cells

Hypotonic Solution Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute (HYPO); High water) Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)! Osmosis Animations for isotonic, hypertonic, and hypotonic solutionsOsmosis

Osmosis - Types of Solutions Hypotonic [water inside] < [water outside] Solutes are higher inside the cell. Water flows in, cell swells. Cell could burst if water flow continues. Swollen red blood cells

Hypertonic Solution Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute (HYPER); Low water) Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)! Osmosis Animations for isotonic, hypertonic, and hypotonic solutionsOsmosis shrinks

Osmosis - Types of Solutions Hypertonic [water inside] > [water outside]. Solutes are higher outside the cell. Water leaves the cell, cell shrinks. Dehydrated red blood cells

Types of transport Passive vs. Active Transport Passive - no energy required Active - energy required

Types of Cellular Transport Passive Transport cell doesn’t use energy 1.Diffusion 2.Facilitated Diffusion 3.Osmosis Active Transport cell does use energy 1.Protein Pumps 2.Endocytosis 3.Exocytosis high low This is gonna be hard work!! high low Weeee!! ! Animations of Active Transport & Passive TransportAnimations

Types of Transport Passive TransportPassive Transport –Movement across a membrane by diffusion. –Facilitated diffusion - moves down the concentration gradient with the aid of a protein molecule. Most glucose moves this way

2. Facilitated diffusion: diffusion of specific particles through transport/carrier proteins found in the membrane a.Transport Proteins are specific – they “select” only certain molecules to cross the membrane b.Transports larger or charged molecules Facilitated diffusion (Channel Protein) Diffusion (Lipid Bilayer) Passive Transport: 2. Facilitated Diffusion Carrier Protein AB

Types of Transport Active TransportActive Transport –moves from an area of low concentration to an area of high concentration. –Moves up or against the concentration gradient. –Glucose moving from blood stream into liver for storage.

Types of Transport Bulk TransportBulk Transport –Moving large particles across the cell membrane. –Endocytosis - movement –into the cell –Exocytosis - movement out of the cell

Cell changes shape – requires energy EX: Hormones or wastes released from cell

Contractile vacuole full Contractile vacuole empty Paramecium

Bulk Transport Endocytosis - 2 types –Pinocytosis- bulk transport of liquids into the cell. –Phagocytosis- “cell eating”- bulk transport of solids into the cell.

Cell membrane in-folds around food particle “cell eating” forms food vacuole & digests food This is how white blood cells eat bacteria!