NO TYPICAL CELL

No Typical Cell

No Typical Cell

Introduction

A cell is the morphological and functional unit of living organisms. In fact, the cell is the smallest element that can be considered alive. In this way, can be classified living organisms according to the number of cells that have: if you only have one, are called single cell (such as the protozoa or bacteria, microscopic organisms), if they have more, they called multi cellular. In the latter, the number of cells varies from a few hundreds, as in some nematodes, hundreds of billions (10 14), as in the case of human beings. The cells typically have a size of 10 microns and a mass of 1 ng, although cells are much higher.

The cell theory, proposed in 1839 by Matthias Jakob Schleiden and Theodor Schwann, postulates that all organisms composed of cells and all cells derived from other precedents. Thus, all vital functions emanating from the cellular machinery and the interaction between adjacent cells, in addition, possession of genetic information, the basis of inheritance, in its DNA that allows the transmission from generation to generation.

The appearance of the first organism living on Earth commonly associated with the birth of the first cell. While there are many hypotheses that speculate how it happened, it usually describes the process started by the transformation of organic molecules on inorganic appropriate environmental conditions, after this, these bio molecules leading to associated entities capable of self-replication complex. There is possible evidence fossils of cellular structures in rocks dated at around 4 or 3.5 billion years ago (Gagiga-years.) Found very strong evidence forms celled life fossilized microstructures in rocks of the formation Strelley Pool in Western Australia, with a 3.4 Ga old. This would be the fossil of cells oldest found to date. Additional evidence shows that their metabolism would be anaerobic and based on the sulphur.

There are two predominant cell types: the prokaryotes (cells comprising archaea and bacteria) and eukaryotes [traditionally divided animals and plants, but also include fungi and protists, which also have cells with characteristic properties] (Blum, 2009, pp. 120-121).Discussion

The unit cell as the morphological and functional of all living things. In fact, the cell is the smallest element that can be considered alive. As such, it has a membrane of phospholipids with maintaining a selective permeability internal environment highly ordered and distinct from the external environment in terms of composition, subject to homeostatic control, which consists of bio molecules and some metals and electrolytes. The structure is self-actively through metabolism, ensuring coordination of all cellular elements and their perpetuation through replication through a genome encoded by nucleic acids. That part of biology that deals with it is the cytology.Structural features

According to Sherwood (2006, pp. 20), the structure of cell varies. A human body contains billion of trillions cells, which classified into around 200 different cell types based on their definite variations in functions and composition. Therefore, Sherwood is of the idea that there is no such thing as a typical cell because of their miscellaneous compositional and functional ...