Cell Wall
external image cellwallfigure1.jpg


Location- Cell walls are located in plant cells and they are the layer just outside of the cell membrane.

Fuctions:

  • Structural support
  • Maintains cell shape
  • Helps plants grow strongly
  • Stores carbohydrates
  • Protects from pathogens and dehydration
  • Prevents cell over-growth when water enters the cell
Consists of:
Cellulose- A polysaccharide which consists of glucose monomers that are joined by glycosidic linkages.
Chitin- A polysaccharide of an amino sugar that is found in most fungi and exoskeletons of all arthropods.

More Information:

  • The cell wall offers a very defined difference between plant cells and other eukaryotic cells.
  • The cell wall has a strength that cannot be compared to most outer cellular membranes.
  • The cell wall is the main factor in determining the different functions of plants in comparison to animals.
  • In new cells the cell wall is not as thick or developed. It is not rigid and it is very thin.
  • When the cell has grown to its full potential, it may maintain its primary wall and become thicker. It may put out new layers of a different material that is known as the secondary cell wall.
  • Even though the cell wall is rigid, chemical signals and cellular seepage can still pass through and between cells.
PLANT CELL STRUCTURE!
http://www.cellsalive.com/cells/cell_model.htm

Cell Membrane:
Cell Membrane:

external image cell_membrane.gif
    • Receptors
    • Pores
    • Enzymes

    • Sodium
    • Potassium
    • Calcium

    • Protiens
    • Lipids
The cell membrane is not one solid piece. Everything in life is made of smaller pieces and a membrane is no different.
Compounds called proteins and phospholipids make up most of the cell membrane.


Plastic Bag Imagination:
When you think about a membrane, imagine it is like a big plastic bag with some tiny holes.
Plastic Bag Make Up: Phospholipids
The bag holds all of the cell pieces and fluids inside the cell and prevents things from coming inside
The holes are there to let some things move in and out of the cell.
The proteins are found around the holes and help move molecules in and out of the cell.
Scientists describe the organization of the phospholipids and proteins with the mosaic models. That model shows that the phospholipids are in a shape like a head and a tail. The heads like water and the tails do not like water. The tails bump up against each other and the heads are out facing the watery area surrounding the cell. The two layers of cells are called the bilayer.
Mosaic Model:
external image fluid_%20mosaic_model.jpg

















Interactive Sites about Cell Membranes

http://www.johnkyrk.com/cellmembrane.html
http://www.wisc-online.com/objects/index_tj.asp?objid=ap1101
http://www.susanahalpine.com/anim/Life/memb.htm
external image SPL_6_P780110-Fibroblast_cells_showing_cytoskeleton.jpg
Cytoskeleton: Different proteins that are meshed together inside cells.

Location: Fills the cytoplasm of cells

Functions:

  • Cytokinesis- The movement of cells
  • The organization of organelles or ,structures that are similar to organelles, inside of the cell
  • Provides structure for cells
  • Essential for the dividing of cells during reproduction

Structure- The cytoskeleton is a complex network of various proteins that cross through the cytoplasm.
- The proteins that make up the cytoskeleton make long twisted strands, and the proteins are flexible and strong.external image cytoskeleton02.jpg
- Cytoskeleton is distributed throughout out cells
- Has three main structural components:

  1. Microfilaments- The smallest component of the cytoskeleton; made of G-actin protein and are wound in a helical shape.
  2. Intermediate filaments- Twisted in a cord shape and are made of keratin. They are strong and resist tension.
  3. Microtubules- Largest component of the cytoskeleton; made of alpha and beta tubulin which form hollow cylinders.


Interesting Facts:
Changes in the cytoskeleton are observed in cancer cells.
Cancer cells often show increased movement.

The essential role of the cytoskeleton in the growing of cells has led to the use of drugs that inhibit the cytoskeleton as anti-cancer drugs.
Examples of drugs:Taxol and Vinblastine


external image cytoskeleton.gif

Videos about Cytoskeletons:
http://www.medicalvideos.us/videos-2029-Cell---Cytoplasm-and-cytoskeleton
http://www.wiley.com/college/pratt/0471393878/student/animations/actin_myosin/index.html

By: Cassie and Taylor!

BIBLIOGRAPHY:

"Cell Models:An Interactive Animation." Cells Alive! Web. 29 Oct. 2009. <http://www.cellsalive.com/cells/cell_model.htm>.
"Cell Organelles:Cytoskeleton."
Cells Alive! 2006. Web. 29 Oct. 2009. <http://www.cellsalive.com/cells/cytoskel.htm>.

Cell Organelles: Membrane and Cytosyol. Quill Graphics. Web. 27 Oct. 2009. http://www.cellsalive.com/cells/membrane.htm.
"Cell Wall." Cell Anatomy. Think Quest. Web. 29 Oct. 2009. http://library.thinkquest.org/C004535/cell_wall.html.
"Cell Wall."
Cell Anatomy. Think Quest. Web. 29 Oct. 2009. <http://library.thinkquest.org/C004535/cell_wall.html>.
"Cytoskeleton."
Cytoskeleton. Web. 29 Oct. 2009. <http://biology.kenyon.edu/HHMI/Biol113/cytoskeleton.htm>.
Cellular Biology: Cell Structure. Sandi Barkalow. Web. http://library.thinkquest.org/12413/structures.html.
"Essential Biochemistry - Actin and Mytosin." Essential Biochemisty - Actin and Mytosin. Ed. Pratt College. Pratt College. Web. 29 Oct. 2009. http://www.wiley.com/college/pratt/0471393878/student/animations/actin_myosin/index.html.
Membrane Structure: The Fluid Mosaic Model. Freeman and Co. and Sumanas, 2000. Web. 28 Oct. 2009. <http://www.susanahalpine.com/anim/Life/memb.htm>.
"Plant cell Wall."
Molecular Expressions. Florida State University, 1995. Web. 28 Oct. 2009. <http://micro.magnet.fsu.edu/cells/plants/cellwall.html>.
"Plant Cell Walls."
Plant Cell wall Basics. University of Georgia. Web. 28 Oct. 2009. <http://www.ccrc.uga.edu/~mao/intro/ouline.htm>.
"Rader, Andrew. "Cell Structure."
Biology4Kids. 1997. Web. 28 Oct. 2009. <http://www.biology4kids.com/files/cell_wall.html>.
The Cell Membrane. R Nave. Web. 27 Oct. 2009. http://hyperphysics.phy-astr.gsu.edu/Hbase/biology/celmem.html.
"The Cytoskeleton."
The Cytoskeleton. 14 Oct. 2009. Web. 29 Oct. 2009. <http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Cytoskeleton.html>.