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Cellular Transport Involves absorption and circulation of materials Cellular Transport the movement of molecules into, around or out of the cell ◦ absorption – materials ENTER the cell ◦ circulation – materials are moved throughout the cell ◦ cyclosis – the circulation of the cytoplasm cyclosis animation Plasma Membrane Review Notes on Plasma Membrane from the Cell Organelle Unit. ( You will be held responsible on this Unit Plasma Membrane controls the movement of molecules into or out of the cell Proteins Integral proteins Transport proteins Peripheral Proteins PLEASE REVIEW Specific Proteins G-Protein Coupled Receptors: Passes 7 time back and forth through membrane Found mainly in Eukaryotes including yeast and animal cells. Involved in many diseases, and are also the target of approximately 40% of all modern medicinal drugs Specific Proteins G-Protein Coupled Receptors: Passes 7 time back and forth through membrane Just FYI: ( no need to write ) Two American scientists: Robert Lefkowitz and Brian Kobika won the Nobel Prize in Chemistry in 2012 for identifying the structure of the GPCR Carbohydrates in Cell Membrane function in a cell’s ability to distinguish one type of neighboring cell from another CELL TO CELL RECOGNITION This is the basis for rejection of foreign cells by the immune system Types of Cellular Transport I. Passive Transport Weeee!! ! no cellular energy required high A. Diffusion B. Facilitated Diffusion C. Osmosis low 1. Passive Transport: ex: Diffusion Move from HIGH to LOW concentration ◦ passive transport ◦ no energy needed diffusion diffusion of water osmosis Simple Diffusion Simple Diffusion substances pass through a membrane without the aid of transport proteins There is a net movement of molecules from areas of high concentration to areas of low concentration There is a net movement of molecules from areas of high concentration to areas of low concentration Molecules move down the concentration gradient The concentration gradient Movement of a substance down its concentration gradient DOES NOT REQUIRE ENERGY Diffusion stops once molecules are evenly distributed – dynamic equilibrium Molecules are still in constant motion, but same number of molecules move in one direction as in the opposite direction How Diffusion Works Molecules that are able to diffuse: - non-polar molecules - polar molecules small enough to fit through membrane pores Examples: Oxygen – Non-polar so diffuses very quickly Carbon dioxide – Polar but very small so diffuses quickly Water – Polar but also very small so diffuses quickly Molecules that are able to diffuse: Small Molecules CAN diffuse Large Molecules CAN NOT diffuse STARCH TOO BIG - GLUCOSE SMALL ENOUGH PROTEIN TOO BIG - AMINO ACID SMALL ENOUGH TRIGLYCERIDES TOO BIG - FATTY ACIDS and GLYCEROL SMALL ENOUGH B. Osmosis Osmosis: diffusion of water through a selectively permeable membrane Water moves from high to low concentrations Osmosis animation •Water moves freely through pores. •Solute (green) to large to move across. Key Terms Hypertonic Solution: A solution that has more solutes than another solution to which it is compared Hypotonic Solution: A solution that has less solutes than another solution to which it is compared Isotonic Solution: A solution that has the same amount of solutes than another solution to which it is compared Osmotic Pressure The pressure which needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane. Solutions and a Cell Hypotonic Solutions: have a lower concentration of solutes and a higher concentration of water than inside the cell Result: water moves from the solution to inside the cell): cell swells and bursts open (cytolysis)! Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Solutions and a Cell Hypertonic solutions: have a higher concentration of solutes and a lower concentration of water than inside the cell Result: water moves from inside the cell into the solution: cell shrinks (Plasmolysis)! Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Solutions and a Cell Isotonic solutions: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell. Result: water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium) How Osmosis Works Hypertonic Solutions What type of solution are these cells in? A B C Osmosis in animal cells Osmosis in plant cells Transport Videos: Great Website for Review Video Osmoregulation the control of the levels of water and mineral salts in body fluids to maintain homeostasis of the body's water content Osmoregulation the control of the levels of water and mineral salts in body fluids to maintain homeostasis of the body's water content it keeps the body's fluids from becoming too dilute or too concentrated. How do organisms function? Bacteria and plants have cell walls that prevent them from over-expanding. In plants the pressure exerted on the cell wall is called turgor pressure osmosis in elodea cells A protist like paramecium has contractile vacuoles that collect water flowing in and pump it out to prevent them from over-expanding. contractile vacuoles • Salt water fish pump salt out of their specialized gills so they do not dehydrate. • Animal cells are bathed in blood. Kidneys keep the blood isotonic by removing excess salt and water. C. Facilitated Diffusion diffusion of specific particles through transport proteins found in the membrane a. Transport Proteins are specific – they “select” only certain molecules to cross the membrane Channel Proteins animations C. Facilitated Diffusion diffusion of specific particles Through transport 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 Channel Proteins animations Facilitated Diffusion Facilitated Diffusion ANIMATION ANIMATION #2 II. Active Transport Requires cellular energy (ATP) A. Protein Pumps B. Endocytosis C. Exocytosis This is gonna be hard work!! high low Active Transport Used to transport large molecules through a membrane or to move molecules against the concentration gradient (low→ high concentration) Types of Active Transport A. Protein Pumps – transport proteins that require energy to do work •Example: Sodium / Potassium pumps are important in nerve responses. Types of Active Transport Protein changes shape to move molecules: this requires energy! Sodium Potassium Pumps (Active Transport using proteins) http://www.brookscole.com/chemistry_d/templates/student_resources/shared_resour ces/animations/ion_pump/ionpump.html B. Endocytosis Forming vacuoles to bring molecules into a cell Energy needed!!!!!!!!!! Phagocytosis: “cellular eating” pseudopods (false limbs) are formed – the particle is engulfed and digested within a lysosome In phagocytosis the cytoplasm is pushed OUTWARD to form pseudopods This is called cytoplasmic streaming Lunch Time Time to eat Pinocytosis – “cell drinking” In the process of pinocytosis the plasma membrane “gulps” particles dissolved in fluid by forming tiny vesicles Pinocytosis – “cell drinking” In the process of pinocytosis the plasma membrane “gulps” particles dissolved in fluid by forming tiny vesicles Nonspecific – all solutes dissolved in the droplet are taken into the cell In pinocytosis the cell membrane is pulled by the cytoskeleton in toward the center of the cell C. Exocytosis intracellular vesicle moves to the plasma membrane and fuses with it to spill contents outside of cell •Animations of Active Transport & Passive Transport