Chapter 2BOT3015L

Introduction to Autotrophs and Osmotrophs

Presentation created by Danielle SherdanAll 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

ReminderPreparation for Class

Prior to each class:1. Read the lab materials2. Drawing list3. Review questions4. 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_ mm2. _40_ mm

_√_ Apply 20 µl 100 µM GA to 1st leaf of plants 1, 2 and 3.

___ Apply 20 µl 10 µM GA to 1st 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

QuickTime™ and aCinepak 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 vacuolePut 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

chromosomereplication 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

Homologouschromosomes

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 Low resolution

High magnification Low 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 stage2. Set objective3. Looking from the side, not in the ocular, bring the

objective very close to the coverslip4. 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