Chapter 4 - Cell Structure & Function PDF

L A B O R A T O R Y 4 Cell Structure and Function  Cell Structure and Function Learning Outcomes 1. Prokaryotic Versus Eukaryotic Cells 2. Animal Cell and Plant Cell Structure 3. Diffusion 4. Osmosis: Diffusion of Water Across Plasma Membrane 5....

L A B O R A T O R Y 4 Cell Structure and Function  Cell Structure and Function Learning Outcomes 1. Prokaryotic Versus Eukaryotic Cells 2. Animal Cell and Plant Cell Structure 3. Diffusion 4. Osmosis: Diffusion of Water Across Plasma Membrane 5. pH and Cells Introduction The Cell Theory states that all organisms are made up of cells which come only from other cells. Cell: the basic structural and functional unit of living organisms. The content of a cell, called the cytoplasm, is bounded by a plasma membrane which regulates the movement of molecules into and out of the cytoplasm. 4.1 Prokaryotic Vs Eukaryotic Cells Prokaryotes Eukaryotes They do not have the They do have membrane organelles (membranous bounded organelles with bodies with a specific specific structure and structure and function). function. They have a nucleoid region The eukaryotic cells do in which the DNA is placed contain nuclei with but not enclosed by a membrane bound. membrane. Examples: Protozoan, Examples : Bacteria The fungi, animal, and plant prokaryotic cells do not cells. contain nuclei (including cyanobacteria). 4.1 Prokaryotic Vs Eukaryotic Cells 4.1 Prokaryotic Vs Eukaryotic Cells Observation: Prokaryotic/Eukaryotic Cells Two microscope slides on display will show the main difference between Prokaryotic and Eukaryotic cells. Prokaryote Cuboidal cells from a human kidney 4.2 Animal Cell and Plant Cell Structure The nucleus in a eukaryotic cell is bounded by a nuclear envelope. The cytoplasm, found between the plasma membrane and the nucleus, consists of background fluid and the organelles. Many organelles are membranous, such as endoplasmic reticulum, Golgi apparatus, peroxisome, and chloroplast. 4.2 Animal Cell and Plant Cell Structure 4.2 Animal Cell and Plant Cell Structure Figure 4.2 Animal Cell Structure 4.2 Animal Cell and Plant Cell Structure Animal Cell Structure Nucleus Nucleolus Cytoskeleton Rough ER Smooth ER Cell Membrane Centrioles Centrosome Mitochondria Lysosome Vesicle Golgi apparatus 4.2 Animal Cell and Plant Cell Structure Figure 4.3 Plant Cell Structure 4.2 Animal Cell and Plant Cell Structure Plant Cell Structure Central Vacuole Nucleus Nucleolus Centrosomes Mitochondria Rough ER Smooth ER Microtubules Cell Membrane Golgi Apparatus Granum Cell Wall 4.2 Animal Cell and Plant Cell Structure 4.2 Animal Cell and Plant Cell Structure The Animal Cell Centrioles within centrosome. Structure: Hollow tubes formed by microtubules. Located near to the nucleus in pairs Centrioles at right angle to one another. Found only in animal cell. Function: Associated with cell division. Electron micrograph 4.2 Animal Cell and Plant Cell Structure The Plant Cell Exhibits all basic features of an animal cell, additional features of a plant cell are: 1. Cell wall - contains cellulose fibrils ,provide support and protection. 2. Chloroplast – double membranous structure carrying chlorophyll and performs photosynthesis. 3. Large central vacuole –membranous sac filled with fluid, helps in storage and maintains turgor pressure. 4. Centrosome area without centrioles. 4.2 Animal Cell and Plant Cell Structure The Plant Cell Large Central vacuole Centrosome Cell wall Chloroplast 4.2 Animal Cell and Plant Cell Structure Observation: Plant Cell Structure Prepare a wet mount of a small piece of young Elodea leaf in fresh water. Notice Cyclosis. 4.3 Diffusion The movement of molecules from a higher to a lower concentration until equilibrium is achieved and the molecules are distributed equally. 4.3 Diffusion Experimental Procedure: Diffusion Solute Diffusion Through a Semisolid Potassium permanganate (KMnO4) 1.5% Gelatine (or agar) Petri dish 4.3 Diffusion Experimental Procedure: Diffusion Solute Diffusion Through a Liquid Beaker Water Potassium permanganate (KMnO4) 4.3 Diffusion Experimental Procedure: Diffusion Solute Diffusion Through Air 4.3 Diffusion Experimental Procedure: Diffusion 1. Record time zero and final time then calculate the length of time and speed of diffusion. 2. Record in the table below. 4.3 Diffusion Solute Diffusion Across the Plasma Membrane Some molecules (small and nocharged) can diffusion across a plasma membrane, and some (large) cannot. Dialysis tube membrane simulates a plasma membrane. 4.3 Diffusion Experimental Procedure: Solute Diffusion Across the Plasma Membrane 4.3 Diffusion Experimental Procedure: Solute Diffusion Across the Plasma Membrane Observation The contents of the bag turns blue: Iodine being a micromolecule diffuses inside the bag, contact with starch & blue color develops. Starch being a macromolecule cannot diffuse outward the bag. Glucose diffuses out into the tube ( confirm with Benedict’s test). 4.3 Diffusion Experimental Procedure: Solute Diffusion Across the Plasma Membrane 4.4 Osmosis: Diffusion of Water Across Plasma Membrane The diffusion of water molecules from area of higher concentration to the area of lower concentration through a semi permeable membrane (cell membrane). 4.4 Osmosis: Diffusion of Water Across Plasma Membrane Experimental Procedure: Speed of Osmosis 4.4 Osmosis: Diffusion of Water Across Plasma Membrane Tonicity Tonicity is the relative concentration of solute and also of solvent, outside the cell compared with that inside the cell. 4.4 Osmosis: Diffusion of Water Across Plasma Membrane Tonicity Isotonic solution has the same concentration of solute as the cell; there is no net movement of water. Hypertonic solution has a higher solute concentration than the cell; water moves out of the cell into solution. Hypotonic solution has a lower solute concentration than the cell; water moves into cell from solution. 4.4 Osmosis: Diffusion of Water Across Plasma Membrane Tonicity Figure 4.8 Red Blood Cells (Animal Cells) Crenation Hemolysis 0.9% NaCl solution 10% NaCl solution 0.9% NaCl plus distilled water solution 4.4 Osmosis: Diffusion of Water Across Plasma Membrane Tonicity Experimental Procedure: Effect of Tonicity on Red Blood Cells 1. Sheep blood is treated with the following solutions: a) Tube 1: 0.9%NaCl - Isotonic b) Tube 2: 10%NaCl - Hypertonic c) Tube 3: 0.9% NaCl plus distilled water solution - Hypotonic 2. Wait 15 mins, and then prepare a slide for each sample. 4.4 Osmosis: Diffusion of Water Across Plasma Membrane Tonicity Experimental Procedure: Effect of Tonicity in Red Blood Cells 3. Record your findings below. 4.4 Osmosis: Diffusion of Water Across Plasma Membrane Tonicity Elodea (Plant Cells) Plasmolysis 4.4 Osmosis: Diffusion of Water Across Plasma Membrane Tonicity Experimental Procedure: Elodea Cells 1. Wet mounts of Elodea leaf are prepared using: 1. Fresh water - Hypotonic 2. 10% NaCl - Hypertonic 2. The cells are observed under the microscope. 4.4 Osmosis: Diffusion of Water Across Plasma Membrane Tonicity Experimental Procedure: Elodea Cells 3. Complete the table below. 4.4 Osmosis: Diffusion of Water Across Plasma Membrane Tonicity Experimental Procedure: Potato Strips 1. Two strips of potato (7 cm x 1.5 cm) to be placed in the following solutions: 1. Tube 1: Water 2. Tube 2: 10% Sodium chloride (NaCl) 2. After 1 hr, observe strips for limpness (water loss) or stiffness (water gain). 4.5 pH and Cells The pH of a solution indicates s its hydrogen concentration [H+]. The pH scale ranges from 0 to 14 as shown below. 4.5 pH and Cells The concept of pH is important for living organisms because they are very sensitive to hydrogen ion concentration (pH). Buffers are chemicals that take up excess Hydrogen ions or Hydroxide ions to maintain the pH at a constant level. 4.5 pH and Cells Experimental Procedure: pH and Cells 1. Label 3 test tubes, and fill them with to the halfway mark as follows: Water Buffer Simulated cytoplasm 2. Determine the pH of each tube. 3. Add 5 drops of 0.1 N hydrochloric acid (HCl) to each tube, shake and determine the new pH for each tube. 4.5 pH and Cells Experimental Procedure: pH and Cells 4. Record your results in the table below. 4.5 pH and Cells Experimental Procedure: Effectiveness of Antacids 1. Use a mortar and pestle to grind up amount of antacid that is listed as one dose. 2. For each antacid tested, use a 100 ml of phenol red solution diluted to a faint pink to wash the antacid into a 250 ml beaker. Use a stirring rod to dissolve the powder. (phenol red solution is a pH indicator that turns yellow in acid and red in base). 3. Add and count the number of 0.1 N HCl drops it takes for the solution to turn light yellow. 4.5 pH and Cells Experimental Procedure: Effectiveness of Antacids 4. Record your results in the table below.