A cell is the smallest unit of life. The cell is the starting point for all organisms. Some living things (such as bacteria) are composed of one cell, whereas a complex organism such as the human body is composed of trillions of cells. In the multicellular animals, a group of cells makes up tissues, which make up organs, which make organ systems, which in turn form the complete animal
properties of cell include:
isolation from outside material:
The cell has a membrane. The membrane surrounds the cell, isolating it from the outside. The membrane is complex and can contain many channels that allow the cell to communicate with the environment through complicated chemical interactions that happen on the scale of a few molecules at a time. The membrane also regulates the in-and-out flow of certain materials, allowing certain chemicals in (such as food) or out (such as waste), but blocking others
The cytoplasm is not something from Ghostbusters, but instead it is a semifluid matrix which occupies the volume between the nuclear region and the cell membrane. Think of the cytoplasm as the cream filling. The cytoplasm, however, has a more important function: it contains the chemical wealth of the cell. The sugars, amino acids, and proteins that are used to carry out the chemical reactions of the cell are housed within the cytoplasm. All cells share this basic architecture.
"The part of the cell involved in protein synthesis is the endoplasmic reticulum (the "inside cell network") sometimes simply called the ER. The ER is a finely divided system of membrane-enclosed compartments with an interconnecting network of tubules.
Most, but not all eukaryotic cells, plant and animal, contain a specialized internal membrane system called the Golgi apparatus. The major function of these organelles is to process and export of materials from cells and to make lysosomes, and other vacuoles.
Mitochondria are small cytoplasmic organelles found in all eukaryotic cells that use oxygen in the release and conversion of energy. They contain a highly specialized and integrated system of enzymes and other proteins that progressively release energy from fuel molecules and convert it into a form that can be used for anabolism and movement.
The largest and most clearly visible of the cell's constituents is the nucleus. Within the nucleus, DNA molecules, the cell's genetic machinery, are stored, repaired, transcribed and eventually replicated.
properties specific to plant cells:
protection from outside:
The cell wall is a box-like layer of material synthesized by plant cells outside the plasma membrane. Hooke saw the cell walls of cork cells when he first looked through his microscope. Cellulose fibers form the basic skeletal foundations of cell walls
synthesis of food material:
However the most easily recognizable plastid is the chloroplast, a green organelle that harvests light, then uses the trapped energy to synthesize sugar molecules, which are then stored as starch.
common properties for any cell:
growth and differantiation:
The cell division process in eukaryotic cells is often called Mitosis after the part of the cell cycle that can easily be seen taking place using a light microscope. It is a regularly repeating pattern of events that include the growth of the cell, the synthesis of new DNA molecules and then the packaging and delivery of these new chromosomes to the new daughter cells.