Theory and Cellular
cell theory is one if not "the" fundamental principle of biology. The story of his birth is extremely fascinating. We wanted to go in his milestones, for better appreciate its value but also to understand the ideas and theories not only of scientists of the time as Fontana, Hooke, Schleiden and Schwann that have contributed to this theory, but also to know theories that wants to be antagonistic to it.
The theory is so 'summarized as follows:
- All living organisms are made up of one or more cells
- The chemical reactions of a living organism, including the mechanisms of release of energy and biosynthetic reactions take place within cells;
- cells originate from other cells;
- The cells contain the hereditary information bodies to which they belong, and this information passed from the mother cell to daughter cell.
below illustrate the most important steps that have contributed to the formulation of this fundamental theory: In
seventeenth century. Robert Hooke (1635-1702), a great mathematician, physicist, naturalist and astronomy using a microscope of his invention, he noticed that the cork and other plant tissues were formed by small cavities, separated by walls called "cells" or "little room". In 1838
CE rather Matthias J. Schleiden (1804-1881), German botanist, concluded that all plant tissues are built from sets of organized cells.
In 1839 AD Theodor Schwann (1810-1882), German zoologist, extended Schleiden's observations to animal tissues and proposed a cellular basis common to all living beings. In 1840
is made an introduction of the cell theory. Included the results of experiments and research of many scientists. Among the precursors of this theory was also Felice Fontana.
Felice Fontana (1730-1805) was a scientist in Trentino. During his studies on the skin of eels, was one of the first without the help of microscopes, saw CELL. And the first one who noticed the nucleus of an adult animal cell. Here is his remark made at Naples in 1787, "I had curious to examine the skin of eels gluten, my stools they bring many different thicknesses, and found, after a bit 'diluted, and taken to have a tiny amount, ch' He seemed composed of uniform and irregular blisters, filled with tiny corpiccioli, spheroidal "
In 1858 AD Rudolf Virchow (1821-1902), pathologist, said that the cells may originate only from cells background. When a cell exists, there must be a pre-existing cells, just like an animal arises only from an animal and arises only from a planet a planet.
In 1859 AD new conventions emerged from the evolutionary theory of Charles Darwin: "There is a strong continuity between existing cells and cells that first appeared on Earth"
Microscope
By 1800 the microscope was fallen out of favor for several ragioni.I compound microscopes used in the 18th century, with their systems of lenses with numerical apertures and incorrect available, suffered a high degree of aberration (distortion) chromatic and spherical. With the magnification used (Up to 500 times) images were often confused, and were the dominant optical false, so that these observers largely completed their observations with the fantasies and the microscope had come to serve primarily as a means of entertainment.
Felice Fontana was well aware of the problems of microscopy, and discussed the "tiny mistake and the consequences deduced from microscopic observations. In the Treaty on the venom of the viper, 1787, he wrote: "... A simple bare observation of the whole, may not deserve full confidence, because we assume that there is a necessary and exclusive relationship between the image represented by the microscope real external object ... "
spontaneous generation
Until the middle of seventeenth century it was common belief that God created humans and other higher organisms, and amphibians, worms, the insects would be generated spontaneously from mud. This belief has its origins far removed not only in terms of time but also space. In China it was thought that the bamboo amphibians were born, for the Greek philosophers, life was contained in the material itself and from it emerged spontaneously when the conditions were made favorevoli.La theory of spontaneous generation step through the Middle Ages and the Renaissance and was supported by great thinkers like Newton, Descartes. From the mid-seventeenth
began, however, the first experiments in support of the cell theory. In 1668, the Tuscan FRANCESCO REDI illustrated a series of experiments that were supposed to disprove the generation spontanea.Egli put the veal and fish in some hermetically sealed containers that, leaving others open. After a bit 'of time could note the presence of maggots on rotting meat inside the open containers in which the flies came and went freely, while there was no trace of the sealed containers. Isolated in a separate container and saw that these worms after various transformation, becoming the adult flies. Redi this experiment had proved beyond doubt that the larvae do not come from rotting flesh.
More or less the same time, it did make important discoveries, the naturalist Anton van Leeuwenhoek . It was the first to discover the microscope or to use magnifying glasses, was the first to see and describe bacteria. He was a cloth merchant who lived in the Netherlands and used the lens to see the quality of the materials. In the 1668 trip to England to see English fabrics, found slower more powerful than he had. Back in Holland he developed and tested the lens looking at every thing he had before, until you see the microbes. He made numerous microscopes in silver and gold. His best lenses were 300-500 times larger, allowing him to see protozoa and large batteri.La generation was then transferred to these cards. In fact, the rotting flesh in the long run also gave rise to micro-organisms in closed vessels.
gave an answer to the latter theory, the Italian naturalist Lazzaro SPALLANZZANI , who repeated the experiment, but boiled and hermetically sealed part of the flesh; result, this time even microorganisms could svilupparsi.La dispute continued for many years and finally ended in the mid-nineteenth century when the French biologist Louis Pasteur devised an experiment that would put an end to dibattito.Pasteur personally constructed of glass containers with a long curved neck (swan-neck flasks), which was placed inside the nutrient solution which was boiled for an hour letting the steam came out freely from the orifice end of the curved neck. Off the heat, because of depression caused by the heating, air contaminated by bacteria and other microorganisms. Those in contact with the liquid that were still boiling inside, were killed. After several months, the infusion was still stored in clear demonstration that there were no seeds of any kind, while the outer section of the neck you could see the presence of dust and microorganisms entered the opening terminale.In more clearly showed that the boiling liquid, he had not killed the "active" because it was enough to snap off the neck twisted by placing the liquid in contact with the nutritional ' air, after a few hours would be numb to the presence of spores and germs. What
of spontaneous generation is not the only case in which the scientific community has interpreted natural phenomena on the basis of the existence of substance which is then frantically went to ricerca.L 'air has long been populated by "Vis Vitalis, but also from phlogiston, heat, ether. The conviction we have today that these theories were not true and justified, we only thanks to a rigorous theoretical and experimental research and also thanks to the invention of the microscope and its continuous improvement.
Sources: Books: "Invitation to Biology," Encyclopedia Rizzoli; Google: "Felice Fontana and Biology."
Authors: Fabrizio Loscalzo, Bert Frank, Simon and Di Benedetto Alessandro Zenatti
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