Presentation on theme: "Cell Transportation How things get in and out of Cells."— Presentation transcript:
Cell Transportation How things get in and out of Cells
Transportation is defined as… the movement of materials in or out of a cell…… or the movement of materials throughout an organism…. example: transportation could be the movement of oxygen into a cell and the movement of carbon dioxide out of a cell…..
What is Brownian Movement? Albert Einstein observed the movement of small particles in water. He realized that the particles moved because they were being bombarded by moving water molecules. He later, in one of his first scientific papers, postulated that every particle in a fluid is in constant motion. This constant movement, first observed by Robert Brown, is called Brownian Movement.
How Temperature affects the motion of molecules Temperature is defined as the average transitional velocity (speed) of the molecules in a system. An increase in temperature is actually an increase in the speed of the molecules…. @ 70 degrees Fahrenheit air molecules are traveling at 1,500 mph All molecules exhibit some kind of motion. Therefore, all molecules have temperature. Absolute Zero – temperature at which all motion stops…absolute zero is -459 Fahrenheit…. Welcome to Bruno’s world!!
Semi- Permeability The Plasma Membrane is semi-permeable ( also referred as “selectively permeable” ). A selectively permeable membrane allows the passage of some materials in or out of a cell, and restricts the passage of some materials in or out of the cell.
Solutions Cells are filled and surrounded by many solutions. Solutions are composed of solutes and a solvent. Solute + Solvent Solution Substance to be dissolved The Dissolver Salt + Water Saltwater
Bulk Flow The movement of some materials is referred to as “Bulk Flow”. Bulk flow is the collective movement of substances in the same direction in response to a force or pressure. Blood moving through a blood vessel is “bulk flow”.
2 Types of Cell Transportation Passive Transport * Materials flow down the concentration gradient. * The cell does not use any energy. Active Transport * Movement of solutes against a concentration gradient. * Requires that the cell use energy.
Passive Transport Solutes flow down the concentration gradient. * The cell does not use any energy. The 3 most common types of Passive Transport are: 1. Diffusion 2. Osmosis 3. Facilitated Diffusion
Simple Diffusion Diffusion is the flow of substances from an area, or region, of greater molecular concentration to an area, or region, of lesser molecular concentration. The overall direction of the movement is referred to as the Gradient. Molecules usually move “down the concentration gradient”..... flow from high concentration to low concentration. Eventually a state of “equilibrium” is reached where molecules are uniformly distributed but continue to move randomly.
Simple Diffusion High Concentration of solutes Low Concentration of solutes Direction of Diffusion Down the Concentration Gradient
Osmosis The Diffusion of water across a membrane All living cells must be surrounded by Water. These water environments are classified as by the concentration of solutes in the solution. The environments are classified as: 1. Isotonic 2. Hypertonic 3. Or, Hypotonic
Isotonic Environment ** In an Isotonic solution, the concentration of solutes outside and inside the cell are equal. ** Under these conditions, water diffuses into and out of the cell at equal rates, so there is NO Net Movement of Water.
Hypertonic Environment Concentration of solutes is greater outside the cell than inside the cell. Water will move outside the cell… the cell will shrink and die. 95% Water 5% solute 97% Water 3% solute
Hypotonic Environment Concentration of solutes is greater inside the cell than outside the cell. Water will move inside the cell… the cell will swell, or burst, and die. 97% Water 3% solute 95% Water 5% solute
Facilitated Diffusion The diffusion of solutes through channel proteins in the plasma membrane. Glucose moves in and out of cells through facilitated diffusion.
Pressure Force (push) exerted on a surface as it is bombarded by moving particles. The amount of pressure can be determined using the following formula: Pressure = Force Area
Osmotic Pressure If there are solute molecules only in one side of the system, then the pressure that stops the flow of the solutes is called the osmotic pressure.
Dialysis The diffusion of solutes across a selectively permeable membrane. The term dialysis is usually used when different solutes are separated by a selectively permeable membrane.
Plasmolysis Movement of water out of a cell that results in the collapse of the cell, especially in plant cells with central water vacuoles. Normal cells Plasmolyzed Cells
Turgor Pressure Internal pressure applied to a cell wall when water moves by osmosis out of the cell. The pressure pushes the plasma membrane against the cell wall. Plasmolysis Plasmolysis is the loss of Turgor Pressure… therefore the cell collapses.
Countercurrent Exchange Diffusion of substances between two regions in which substances are moving by bulk flow in opposite directions. Oxygen Flow
Factors which affect the rate of Passive Transport Temperature – the faster the molecules move, the faster they diffuse… the slower the molecules move, the slower they diffuse. Pressure – as you increase, or decrease pressure…. You can affect the rate and direction of flow. Concentration – the larger the population of solutes, the greater the chance of random access through a membrane.
Active Transport *Solutes flow against the concentration gradient. * The cell uses energy…. ATP. *Requires Transport Proteins Types of Active Transport are: 1. Exocytosis 2. Endocytosis a.) Special Transport b.) Phagocytosis c.) Pinocytosis d.) Receptor-mediated
Special Transport Ions are atoms with either a positive or negative electrical charge…. their electron number is not equal to their proton number. Some, not all, ions need to be transported by Special Transport Special Transport. Simply put….during Special Transport, ions are captured by surface proteins and pushed’ or pulled, into the cell…. Because they are forced, the ions can flow, if necessary, against the concentration gradient.... The ions can even flow through like electrical charges on the plasma membrane.
Exocytosis (exo = outside, Cyto = cell) moving substances outside the cell Process of vesicles fusing with the plasma membrane and releasing their content to the outside of the cell.
Endocytosis (endo = inside, cyto = cell) Capture of substances outside the cell when the plasma membrane merges to engulf it. ***There are three types of endocytosis 1. phagocytosis 2. pinocytosis 3. receptor-mediated
Phagocytosis (phago = to eat, cyto = cell) Phagocytosis occurs when undissolved solids enter a cell. The plasma membrane wraps around the solid material and engulfs it, forming a vesicle. Phagocytic cells, such as white blood cells, attack and engulf bacteria in the manner.
Pinocytosis (pino = to drink, cyto = cell) Pinocytosis occurs when dissolved materials enter a cell. The plasma membrane folds inward to form a channel allowing the liquid to enter. The plasma membrane closes off the channel, encircling the liquid inside a vesicle. Oils enter cells through pinocytosis
Receptor-Mediated Endocytosis Occurs when specific molecules bind to specialized “receptors” (proteins) in the plasma membrane. The membrane, the receptors, and the specific molecules, called ligands, fold inward forming vesicles. Hormones target special “target cells” by receptor-mediated endocytosis. Ligand Receptor ProteinMolecule being ingested
Vesicular Transport Vesicles are small membrane-bound macromolecules of the cell and carry materials between organelles in the cell. Cells can use vesicles to transport large particles across the plasma membrane. Both exocytosis and endocytosis are types of vesicular transport.
Summary Molecule Mode of Transportation O 2 Diffusion CO 2 Diffusion H 2 O Osmosis Glucose (C 6 H 1 2 O 2 ) Facilitated Diffusion Ions Special Transport Large Solids (starch, etc) Phagocytosis Large Liquids (oils) Pinocytosis Hormones Receptor-Mediated