Chapter 2 BOT3015L Introduction to Autotrophs and Osmotrophs

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Chapter 2BOT3015LIntroduction to Autotrophs and
Osmotrophs
Presentation created by Danielle Sherdan All
photos from Raven et al. Biology of Plants except
when otherwise noted
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Today

• Plant cells
• characteristics of plant cells
• plastids
• large central vacuoles
• cell wall
• effects of osmosis on plant cells
• cell division

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Microscopy enables the discovery of cells
Slices of cork. Drawing by Robert Hooke, who
coined the term cell in the 1600s
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Modern cell theory

• The modern cell theory states that
• 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
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Generalized diagram of a plant cell
Note As you will observed, much variation from
this generalized diagram exists.
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Cytoplasmic streaming of chloroplasts
Considering their function, why would movement of
chloroplasts by cytoplasmic streaming be
advantageous?
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Amyloplasts store starch
Today, we will use staining techniques (iodine
stains starch) to visualize amyloplasts in potato
tubers
Amyloplasts in a bean root
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Observing the vacuole
What do you expect?
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Osmosis
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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.
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Today

• Plant cells
• characteristics of plant cells
• plastids
• large central vacuoles
• cell wall
• effects of osmosis on plant cells
• cell division

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Mitosis and cytokinesis
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Mitosis (nuclear division)simplified diagram
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Cell division in plants occurs at meristems
Onion root meristem located at tip of root
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Compare mitosis and meiosis
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Comparison chart II mitosis meiosis
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or triploid or tetraploid
or tetraploid or hexaploid, but not triploid,
why?