Chapter 2 BOT 3015 L Introduction to Autotrophs
Chapter 2 BOT 3015 L 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 Leave 10: 05 am space in front for table of contents Time: _√__ Left (thinking) 1. _20_ mm Right (lab work) Measure plant heights 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 1600 s 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 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 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 (1660 s) 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)
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