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Chapter 2 BOT3015L Introduction to Autotrophs and Osmotrophs Organisms able to synthesize nutritive substances required for growth (auto=self, troph=feed/grow) Organisms that take up nutritive substances required for growth by osmosis (osmo=take up from external, troph=feed/grow) Presentation created by Danielle Sherdan All photos from Raven et al. Biology of Plants except when otherwise noted Today • • • Review preparation and notebook organization Plant cells – characteristics of plant cells – plastids – large central vacuoles – cell wall – effects of osmosis on plant cells – cell division Compound light microscope basics Reminder Preparation for Class Prior to each class: 1. Read the lab materials 2. Drawing list 3. Review questions 4. Methods ****************************** 13 June 2005 Notebook (left / right) Treatment of Brassica rapa plants with GA Leave10:05 space in front for table of contents am Time: _√__ Left _20_ (thinking) mm Measure plant heights Right (lab work) 1. 2. _40_ mm _√_ ___ ____ •Interpretations Apply 20 µl 100 µM GA to 1 leaf of plants 1, 2 and 3. •Conclusions Apply 20 µl 10 µM GA to 1 leaf of plants 4, 5 and 6. •Graphs ……..etc.……. •Ideas for future experiments •Answers to review questions and objectives st st • Observations • Solution preparation • Methods • Data collected during experiment Today • • • Review preparation and notebook organization Plant cells – characteristics of plant cells – plastids – large central vacuoles – cell wall – effects of osmosis on plant cells – cell division Compound light microscope basics Microscopy enables the discovery of cells Slices of cork. Drawing by Robert Hooke, who coined the term “cell” in the 1600s Harvesting cork for commercial purposes Modern cell theory The modern cell theory states that 1. All living organisms are composed of one or more cells 2. Chemical reactions of living organisms take place within cells 3. Cells contain the hereditary information of the organisms of which they are a part, and this information is passed from parent cell to daughter cell 4. Cells arise from other cells Generalized diagram of a plant cell Cytoplasmic streaming of chloroplasts QuickTime™ and a Cinepak decompressor are needed to see this picture. Considering their function, why would movement of chloroplasts by cytoplasmic streaming be advantageous? Amyloplasts store starch Amyloplasts in a bean root Observing the vacuole Put cells in a bath of concentrated solution Osmosis Plasmolysis Normal physiological conditions --Low external solute concentration --High internal solute concentration, thus positive pressure inside. --Positive pressure in the plant cell pushes against the restricting cell wall, like a water balloon in a cage. Under high external solute concentrations --External water potential decreases to below that inside the cell, thus osmotic water efflux from the cell. This process is plasmolysis. Today • • • Review preparation and notebook organization Plant cells – characteristics of plant cells – plastids – large central vacuoles – cell wall – effects of osmosis on plant cells – cell division Compound light microscope basics Mitosis and cytokinesis Mitosis (nuclear division) simplified diagram chromosome replication during S phase of cell cycle chromosomes align along metaphase plate Homologous and are attached chromosomes to cytoskeleton chromosomes condense and nuclear envelope degrades nuclear envelope forms around each set of chromosomes chromosomes are pulled apart to opposite poles, notice both sets are identical Cell division in plants occurs at meristems Onion root meristem located at tip of root Compare mitosis and meiosis Total number of cell divisions? Fill in ploidy level in above “cells” Pairing of homologs? Crossing over? Comparison chart II mitosis meiosis Centromeres divide? How many daughter cells are genetically identical to original cell? or triploid or tetraploid… or tetraploid or hexaploid…, but not triploid, why? Today • • • Review preparation and notebook organization Plant cells – characteristics of plant cells – plastids – large central vacuoles – cell wall – effects of osmosis on plant cells – cell division Compound light microscope basics Robert Hooke’s drawing of his microscope (1660s) Light from an oil lamp Water-filled glass globe as condenser Specimen mounted on a pin Focus by changing the distance between the specimen and the lens Compound light microscope components High resolution High magnification Low resolution Low magnification Important points when using microscopes • Using lens paper, clean eyepieces and objectives before and after each lab • Focus. 1. Place the mounted specimen on the stage 2. Set objective 3. Looking from the side, not in the ocular, bring the objective very close to the coverslip 4. Looking through the eyepiece, move the objective away from specimen with the course focus knob until it is in focus 5. Use fine focus to get the best view Coverslip always (a flat specimen (2-D) is optimal for compound light microscopes)