Function of the cell

► Cell serves as the structural building block to form tissues and organ

► Each cell is functionally independent- it can live on its own under the right conditions:

  • it can define its boundaries and protect itself from external changes causing internal changes
  • it can use sugars to derive energy for different processes which keep it alive
  • it contains all the information required for replicating itself and interacting with other cells in order to produce a multicellular organisms
  • It is even possible to reproduce the entire plant from almost any single cell of the plant

► Cell wall

  • protects and supports cell
  • made from carbohydrates- cellulose and pectin- polysaccharides
  • strong but leaky- lets water and chemicals pass through-analogous to a cardboard box

► Cell membrane

  • membrane is made up from lipids – made from fatty acids water-repelling nature of fatty acids makes the diglycerides form a sheet or film which keeps water from moving past sheet (think of a film of oil on water)
  • membrane is analogous to a balloon- the spherical sheet wraps around the cell and prevents water from the outside from mixing with water on the inside
  • membrane is not strong, but is water-tight- lets things happen inside the cell that are different than what is happening outside the cell and so defines its boundaries. Certain gatekeeping proteins in the cell membrane will let things in and out.

► Cytosol – watery inside of cell composed of salts, proteins which act as enzyme

► Microtubules and microfilaments – cables made out of protein which stretch around the cell

  • provide structure to the cell, like cables and posts on a suspension bridge
  • provide a structure for moving cell components around the cell -sort of like a moving conveyer belt.

► Organelles – sub-compartments within the cell which provide different functions. Each organelle is surrounded by a membrane that makes it separate from the cytosol. These include nucleus, mitochondrion, vacuole, ribosome, endoplasmic reticulum, and golgi apparatus.