Electromagnetic energy

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1 Do Now: How is a window screen similar to a cell membrane? Cell Membrane 1. What are some things that can pass through a window screen? 2. What are some things that cannot pass through a window screen? 3. The cell is surrounded by a cell membrane, which regulates what enters and leaves the cell. Why is it important to regulate what moves into and out of a cell? (Plasma Membrane) Chapter 7: Section 77-3 Electromagnetic energy Label the Diagram In 1972, Singer and Nicolson Cell membrane - made of scattered proteins and lipids that make up the phospholipid bilayer. Cell Membrane: Fluid Mosaic Model Fluid meaning movement. Phospholipids move Proteins can move (drift) inside the bilayer EXPERIMENT Researchers labeled the plasma membrane proteins of a mouse cell and a human cell with two different markers and fused the cells. Using a microscope, they observed the markers on the hybrid cell. RESULTS Membrane proteins Fluid Viscous + Mouse cell Human cell Hybrid cell Unsaturated hydrocarbon tails with kinks (b) Membrane fluidity Saturated hydrocarbon tails Mixed proteins after 1 hour CONCLUSION The mixing of the mouse and human membrane proteins indicates that at least some membrane proteins move sideways within the plane of the plasma membrane. Figure 7.5 B 1

2 Membrane Proteins and Lipids Are synthesized in the ER & Golgi apparatus Endoplasmic Reticulum Cell Membrane 1 Transmembrane glycoproteins ER Starch Secretory protein Glycoprotein Phospholipid bilayer Carbohydrate Cholesterol Glycolipid Golgi 2 apparatus Carrier Protein Phospholipid Vesicle Channel Protein Receptor Protein Hydrophilic 3 4 Secreted protein Plasma membrane: Cytoplasmic face Extracellular face Transmembrane glycoprotein Figure 7.10 Phospholipid Phospholipid Bilayer Hydrophobic Membrane glycolipid 3 Parts of a Cell Membrane Cell Membrane Flexible barrier made of special properties to help maintain homeostasis.. homeostasis 1. Phospholipid - a thin flexible sheet arranged in a bilayer. Function:: act as a barrier Function barrier.. Phosphate group Made of phospholipids phospholipids,, proteins,, and carbohydrates proteins Lipids Lipids-- fatty acid chain 2 Sides (Bilayer) 2. Proteins floats in the phospholipid layer. Hydrophilic side (water loving) Hydrophobic side (water fearing) Cholesterol reduces fluidity (movement) in the phospholipid area. Functions: Functions: Some transport substances across the membrane Others help with shape THINK OF AN ICEBERG! 2

3 3 Types of Proteins 1. Channel Proteins 2. Carrier Proteins 3. Receptor Proteins 3. Carbohydrates (glucose) attached to proteins or the phospholipids. Function: help with cell communication Glycoproteins - proteins with carbohydrates attached. Think of an antenna! Protein Functions LET S MAKE AN ANAL0GY! THE CELL MEMBRANE (cell membrane) alive.com/animations/cell-biology.htm (library of websites) (tutorial) The Functions (Roles) For 3 Types of Proteins 1. Channel Proteins Transports stuff! Ex) ions, molecules 2. Carrier Proteins Transports stuff! Does not extend through the membrane. Bonds & drags molecules to release them on the other side

4 3. Receptor Proteins Allows cell to communicate stuff!: - cell recognition - cell signaling Review : Review: Constructing A Cell Membrane Cell Membrane Concentration of substances are held constant to keep cell alive. Cell Membrane Selective Permeability Allows some chemicals to pass through more easily than others. 1. Size Factors Affecting Membrane Permeability Small Molecules Large Molecules Water Starch Oxygen Proteins Glucose Lipids Amino acids NaCl Fatty Acids Glycerol Soluble end products from digestion 4

5 Question #1 2. Electrical Charge Molecules Molecules = always neutral charge (STABLE) Do you think the cell membrane will allow smaller molecules or larger molecules to pass through without using energy? H20 Molecules Ions = (+, - charge) (UNSTABLE) Question Do you think a cell membrane would allow stable or unstable molecules to enter without using energy? 3. Type of permeability of that specific cell Different cells have different types of membranes. Cell membrane Diffusion Particles move constantly, collide, & randomly spread out. Move greater concentration to an area of lesser concentration. NO ENERGY USED = PASSIVE TRANSPORT Simple Diffusion The passage of small molecules through the cell membrane. No ENERGY USED!!!!!!!!!! Examples: H20, C02, O2 hill.com/sites/ /student_view0/chapter38/how _diffusion_works.html 5

6 Equilibrium Facilitated Diffusion Are protein channels that allow diffusion of molecules to travel across the cell membrane. NO ENERGY USED! Example: Glucose Concentration of the solute is the SAME throughout both sides. Molecules ofof dyedye Membrane (cross section) Molecules Net diffusion Keeps passing back & forth Net diffusion Equilibrium HIGH TO LOW CONCENTRATION Osmosis The diffusion of water through a selectively permeable membrane. Animations: Animations: Osmosis how _osmosis_works.html PURE WATER High water concentration SUGAR WATER Low water concentration Closure: Passive Transport Diffusion Osmosis 3 Types of Solutions for OSMOSIS Isotonic: Concentration of solute is the same inside & out Hypertonic: Solution has higher solute concentration that the cell Hypotonic: Solution has lower solute concentration than the cell 6

7 Animal Cells otonic solution Hyp Cell BURSTS! Water into cell Hypotonic Hypertonic Normal Lysed Isotonic Hypertonic solution Isotonic solution Shriveled Water same into & out Cell SHRIVELS! Water out of cell 3 Types of Solutions For Osmosis: Plant Cells Hypotonic Plant cell. Plant cells are turgid (firm) and generally healthiest in a hypotonic environment, where the uptake of water is eventually balanced by the elastic wall pushing back on the cell. Turgid (normal) Cell Swells (Turgid) Water into cell Isotonic Flaccid Water same into & out Hypertonic Plasmolyzed Cell SHRIVELS! Water out of cell DO NOW: What substances will not be able to pass through the cell membrane? Below is a concept splash. Circle the substances you think will not pass through. 7

8 3 Types of Active Transport The process where ENERGY is used to move materials across the cell membrane against the concentration gradient (low to high) TRANSPORT PROTEINS are used! For LARGER molecules Active Transport: Sodium-Potassium Pump (Na/K Pump) 1. Protein Pumps- Transport proteins that require energy to do work Example: Sodium- Potassium pumps are important in nerve response. Protein changes shape-this requires energy Sodium Potassium pump Active Transport 2. Endocytosis The process of taking material into the cell by means of pockets by the cell membrane. A vacuole is formed inside the cytoplasm. Used for LARGER molecules. hill.com/sites/ /student_view0/chapter6/animations.html# ENERGY is USED!!!!!!!!!!!!!!!! Active Transport Endocytosis & Exocytosis 3. Exocytosis (out) The process where a vacuole surrounding a material fuses with the cell membrane, forcing the contents out of the cell. Used for LARGER molecules. ENERGY is USED!!!!!!!!!!!! 8

9 Analyze: Endocytosis or Exocytosis? 2 Types of Endocytosis 1. Phagocytosis Means cell eating The cytoplasm extends & surrounds a particle & package it within a food molecule. hill.com/sites/ /student_view0/chapter6/animations.html# 2. Pinocytosis Means Cell Drinking The process where tiny pockets are formed filled with liquid along the cell membrane. Then pinch off to form a vacuole inside the cell. Passive Transport Closure: Cell Transport Active Transport Diffusion Passive Transport Active Transport Wrap up: A Review The End 9

10 Active Pump For Ions Facilitated Diffusion Ions The End ries/2002/tim_smith/transp/ ogypages/d/diffusion.html#osmosis Osmosis & CF er/cells/c/cell_membrane/ 10

11 Osmosis ee/biobk/biobooktransp.html Osmosis Diffusion, Phagocytosis, Active Transport m Exocytosis Facilitated Transport: Model Honors 4L03/facilitated%20transport.swf ent/resistance/index.html lls/permeability_of_cell_membrane_in_beetroot_cells_l4722.html Plasmolysis NaK Pump & Phagocytosis microscopy-microscopy uk.org.uk/mag/art97/maysnp2.html m 11

12 3 Types of Solutions For Osmosis: Animal Cells Hypotonic solution Isotonic solution Hypertonic solution H H 2O 2O H 2O H 2O Sources Hypotonic= Lysed Normal Shriveled Outside -Low solute concentration (greater water molecules) High to low inside cell. SWELLS Water concentration is the same outside & inside the cell. Hypertonic= Outside- High solute concentration (less water molecules) High to low outside cell 12