Download The plant cell. - Napa Valley College

The plant cell.
Antonie van Leeuwenhoek & Robert Hooke
1 centimeter (cm) =1/10 meter = 0.4 inch
1 millimeter (mm) = 1/1000 meter = 1/ 10 cm
1 micrometer (µm) = 1/1 ,000, 000 meter 1/ 10, 000 cm
1 nanometer (nm) = 1/1000, 000, 000 meter = 1/ 10, 000, 000
1 Angstrom (Å) = 1/ 10,000,000,000 meter = 1/ 100, 000, 000 = 1/10 nm
1 meter = 102 cm = 103 mm = 106 µm = 109 nm = 1010 Å
Stereoscopic or "dissec-ng microscope” Compound light microscope Light
thousand times
-----0.2 µm
Transmission electron microscope electrons
Hundred of thousands times
----0.0002 µm
Scanning electron microscope electrons
One million times
Metal
< 0.0002 µm
Cell theory 1) Living organisms are composed for one or more cells 2) Energy-­‐ releasing and biosynthe?c reac?ons take place within the cells 3) Cells arise from other cells 4) Hereditary informa?on pass from one genera?on to the other vacuoles
Vacuoles have a single membrane: The tonoplast
the vacuole is the largest compartment of most mature plant cells.
Main functions of the vacuole
• Isolating harmful materials
• Containing waste products
• Maintaining turgor within the cell
• Maintaining an acidic internal pH
• Containing pigments and sap
Calcium oxaloacetate crystals a) Druses b) Raphides Plamolysis
components of the cell wall
The cell wall is a cross-linked matrix of:
Cellulose
Lignin
Hemicelluloses: regulate the cell
enlargement
Pectin: attract water to the walls and form
the middle lamella
Glycoproteins: structural proteins
The arrows indicates the middle lamella
Primary cell walls
Unevenly thickened walls.
Primary pit fields and plasmodesmata Primary cell walls
Undifferen?ated cells Support Secondary wall
Alkaloids
Collenchyma
cellulose and pectin
structural support for shoots and
leaves
Sclerenchyma
Tissues that have ceased
elongation.
Mature sclerenchyma is
composed of dead cells
Cellulose, hemicellulose,
and lignin.
Fibers (jute, hemp, henequen)
Secondary wall
Sclereids: small bundles of sclerenchyma tissue in plants that form durable
layers, such as the cores of apples and the gritty texture of pears.
astrosclereids Cell wall
In a secondary wall commonly we can find
S1 Outer layer
S2 Middle layer
S3 Inner layer
In order to increase the thickness and the surface area new cellulose
micro fibrils are placed on top of those previously formed
Cellulose synthase
expansins
Attendance
1.  Define tonoplast 2.  What is plasmolysis? 3.  Why are pec?nes important? 4.  What is the difference between primary pit fields and plasmodesmata?
5.  What are sclereids?
6.  Draw the structure of the complete cell wall and explain how a primary
cell wall differs from a secondary cell wall