Chapter 2 BOT3015L Introduction to Autotrophs and Osmotrophs Presentation created by Danielle Sherdan All photos from Raven et al. Biology of Plants except when otherwise noted 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)

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 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

Notebook (left / right) Left (thinking) Right (lab work) Observations Solution preparation Methods Data collected during experiment Interpretations Conclusions Graphs Ideas for future experiments Answers to review questions and objectives Leave space in front for table of contents ****************************** 13 June 2005 Treatment of Brassica rapa plants with GA Time:10:05 am _√__Measure plant heights 1. _20_ mm 2. _40_ mm _√_Apply 20 µ l 100 µ M GA to 1 st leaf of plants 1, 2 and 3. ___Apply 20 µ l 10 µ M GA to 1 st leaf of plants 4, 5 and 6. ____ ……..etc. …….

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 4. Cells arise from other 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

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 --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. Normal physiological conditions 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 condense and nuclear envelope degrades chromosomes align along metaphase plate and are attached to cytoskeleton chromosomes are pulled apart to opposite poles, notice both sets are identical nuclear envelope forms around each set of chromosomes Homologous chromosomes

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 resolutionLow resolution High magnificationLow magnification

Important points when using microscopes Using lens paper, clean eyepieces and objectives before and after each lab Coverslip always (a flat specimen (2-D) is optimal for compound light microscopes) 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