Introduction: In this lab you observe "typical", undifferentiated, plant cells (parenchyma). You should have note the characteristics that plant cells share with all other eukaryotic cells (the nucleus and membrane-bound organelles) and also note the characters where plant cells differ from animal cells (large central vacuole, plastids, and cell wall).
The whole plant cell
Chromoplasts are found in brightly colored plant tissues
Some brightly colored plant tissues are colored by water soluable pigments located inside the vacuole. Most red,blue and purple flowers are colored in this way. Impatiens flowers are one example.
Leucoplasts can be seen inthe cells along the intact margin of a Zebrina leaf
Chloroplasts can be easily seen in any green plant tissue such as Elodea. Typically plant cells have disk-shaped chloroplasts as seen in this view of a fern gametophyte.
Starch Grains are always associated with plastids in plant cells. This is true even when the starch grain becomes so massive that no other aspect of the plastid is visible with the light microscope. Starch grains are easily seen in potato tissue.
The Cell Wall
In tissues, the primary plant cell wall is perforated with cytoplasmic tunnels that connect the protoplasts of adjascent cells. These channels are barely resolvable with the light microscope. In lab students view tissue from the endosperm of Diospyros (Persimmon). In this tissue, nutrients are stored in the form of hemicellulose in the primary walls. Because these walls are so thick the plasmodesmata are extremely long and this renders them visible to the light microscope. The boundary between adjacent cells (the middle lamella) is also clearly visible in the tissue.
Plant cells commonly form crystals of calcium oxylate inside their vacuoles. These can take on a variety of different forms. Two were seen in lab.
a. Raphides: These are needle-shaped.
Link to view of raphides in Impatiens petal tissue
b. druses: These are spherical with a jagged margin
Link to view of druses in Begonia petiole tissue
The Plant Cell as Seen with the Transmission Electron Microscope
All the electron micrographs used here are from Dr. Eldon Newcomb:
Go to our complete directory of Electron Micrographs
1. Young Plant Cell: view of nucleus, mitochondria and vacuoles
2. Plant Cell: view of nucleus with nucleolus, mitochondria chloroplasts and vacuole
3. Plant Cell: View of nuclear envelope, microbodies, mitochondria, and a chloroplast
4. Plant Cell: view of a chloroplast showing detail of the grana
7. Plant Cell: View of leucoplast with mitochondrion and endoplasmic reticulum
8. Plant Cell: View of microtubules below the cell wall (glancing section)
9. Plant Cell: View of microtubules below the cell wall (cross section of microtubules)
10. Plant Cell: View of plasmodesmata (longitudinal secton)
11. Cell Wall: View of plasmodesmata (cross section)
12. Plant Cell: view of parenchyma cell with a large central vacuole
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