Cell Membrane Transport Mechanisms PDF

Recalling from the last lesson 1. State the function of the mitochondria? 2. State which organelle is present in the plant cell but not the animal cell, and which is in the animal cell but not the plant cell. 3. State the function of the vacuole in a plant cell and animal cell. Topic 2 – The Cell...

Recalling from the last lesson 1. State the function of the mitochondria? 2. State which organelle is present in the plant cell but not the animal cell, and which is in the animal cell but not the plant cell. 3. State the function of the vacuole in a plant cell and animal cell. Topic 2 – The Cell System 2-3 Obtaining & Removing Materials What is the primary role of the cell membrane in the cell function Molecule movement Imagine… You walk across a store in the mall and smelled something delicious or... You stand near someone who belches and you know what he had for lunch Cell Membrane – where is it? Cell Membrane • All cells are surrounded by it • Controls the movement of materials in and out of the cell • Maintain homeostasis • Selectively permeable – some substances can pass but some cannot. • Movement of materials happen by - Passive transport - Active transport Passive Transport • Materials or substances move without the need of energy • Movement is natural due to differences in concentration which happen because of particle movement. How to particles in matter move? Kinetic Model of Matter and Diffusion • Matter is made of particles • Particles of solids, liquids and gases are in constant random motion Kinetic Particle Theory Comparing the physical properties of solids vs liquids vs gases State Solid Liquid Gas Shape Fixed Not fixed Not fixed Fixed Fixed Not fixed (fixed / not fixed) Volume (fixed / not fixed) Which is which? Which do you think is solid or liquid or gas? Why? A B C Why? State Solid Liquid Gas Particle arrangement Regular arrangement, close together Irregular arrangement, a little further apart Irregular arrangement, very far apart Particle movement Vibrate about in fixed positions Roll and move around each other Move with high speeds around the container Bond between particles Very strong bonds holding particles together Relatively strong bonds that break and reform Little or no bond between particles Particles in a Solid Solid particles: • Closely packed • Vibrate in fixed positions • Bond between particles is very strong Particles in a Liquid Liquid particles: • Closely packed • Roll and move around each other • Bond between particles is still strong (but not as strong as when in solid state) Particles in a Gas n Gas particles: • Very far apart • Move about randomly at high speeds • Little or no bonds between gas particles Speed of particle movement and temperature • In general, particles move faster when the temperature is higher Passive Transport • Materials or substances move without the need of energy • Movement is natural due to differences in concentration which happen because of particle movement. 3 different forms of passive transport 1. Diffusion 2. Osmosis 3. Facilitated diffusion Diffusion • Movement of molecules from a region of higher concentration to a region of lower concentration. • Eventually molecules are evenly distributed throughout • Equilibrium established Diffusion • Movement of molecules from a region of higher concentration to a region of lower concentration. • Eventually molecules are evenly distributed throughout • Equilibrium established Diffusion • Diffusion can happen in solids, liquids and in gases. • Which medium do you think will allow the fastest diffusion? Why? Diffusion • Diffusion occurs at a different rate when the temperature of the medium is different. • Will diffusion be faster when the medium is hot or cool? • Why? Diffusion Demonstration hot water cold water Osmosis • Movement of water molecules from a region of higher water concentration to a region of lower water concentration through a selectively permeable membrane • Eventually the water concentration is equal • Equilibrium is established Osmosis • Water is essential – without water, most cells die. • When the environment is dry (with very little water), → water may move out of cells → cytoplasm shrinks away from the cell wall → cell may die Facilitated Diffusion • Small molecules e.g. oxygen, carbon dioxide, water freely diffuse across cell membrane • Larger molecules e.g. sugar cannot move easily across cell membrane • Undergo facilitated diffusion Facilitated Diffusion Proteins provides a pathway for large molecules to diffuse into the cell Active Transport • Move molecules from a region of lower molecule concentration to a region of higher molecule concentration • Cells use up energy to move molecules across the cell membrane against the natural concentration gradient. Active Transport Transport proteins pick up molecules, alter the shape of the transport protein and push the molecule into the cell across the cell membrane. Active Transport • Substances like calcium, potassium, and sodium are moved in and out of cells by active transport Moving of Large Particles • Some materials (e.g. food particles) are too large to cross the cell membrane Even the pores of the transport proteins are not large enough. • These materials move in to the cell by endocytosis out of the cell by exocytosis Endocytosis Vacuole Exocytosis Vacuole Rip out pg 83 to 89 (7B due 10/9, 7A due 10/11) Do Pg 85: Reading check, Math toolbox Pg 86: Model It Pg 87: Fill in the blanks Pg 88: Reading check & Large molecule moving Pg 89: Lesson 3 check all ( except Quest check in)