Cell: The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. can be classified as unicellular (consisting of a single cell; including most bacteria) or multicellular (including plants and animals). Humans contain about 10 trillion cells. Most plant and animal cells are between 1 and 100 µm and therefore are visible only under the microscope.
The cell was discovered by Robert Hooke in 1665. In 1835, before the final cell theory was developed, Jan Evangelista Purkyně observed small "granules" while looking at the plant tissue through a microscope. The cell theory, first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann, states that all organisms are composed of one or more cells, that all cells come from preexisting cells, that vital functions of an organism occur within cells, and that all cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells.
The word cell comes from the Latin cellula, meaning "a small room". The descriptive term for the smallest living biological structure was coined by Robert Hooke in a book he published in 1665 when he compared the cork cells he saw through his microscope to the small rooms monks lived in.Multicellularity in Animals: There are more than 100 visibly distinguishable kinds of differentiated cells in the vertebrate animals. These are organized into issues; the tissues into organs. Groups of organs make up the various systems - digestive, excretory, etc. of the body.
Multicellularity in Plants: Like other organisms, plant cells are grouped together into various tissues. These tissues can be simple, consisting of single cell type, or complex, consisting of more than one cell type. Above and beyond tissues, plants also have a higher level of structure called plant tissue systems. There are three types of tissue systems: dermal tissue system, vascular tissue system and ground tissue system.
An Unique Experiment: An evolutionary transition that took several billion years to occur in nature has happened in a laboratory, and it needed just 60 days.
Under artificial pressure to become larger, single-celled yeast became multicellular creatures. That crucial step is responsible for life’s progression beyond algae and bacteria, and while the latest work doesn’t duplicate prehistoric transitions, it could help reveal the principles guiding them.
“This is actually simple. It doesn’t need mystical complexity or a lot of the things that people have hypothesized — special genes, a huge genome, very unnatural conditions,” said evolutionary biologist Michael Travisano of the University of Minnesota, co-author of a study Jan. 17 in the Proceedings of the National Academy of Sciences.One Cell in Multicellular Organization: “Multicellularity is the ultimate in cooperation,” said Travisano, who wants to understand how cooperation emerges in selfishly competing organisms. “Multiple cells make up an individual that cooperates for the benefit of the whole. Sometimes cells give up their ability to reproduce for the benefit of close kin.”
The Paramount Factor The new study suggests that environmental conditions are paramount: Give single-celled organisms reason to go multicellular, and they will.
The Future Implications: Targeted breeding of single-celled organisms into complex, multicellular forms could also become a biotechnological production technique.
“If you want to have some organism that makes ethanol or a novel compound, then — apart from using genetic engineering — you could do selection experiments” to shape their evolution, Travisano said. “What we’re doing right here, engineering via artificial selection, is something we’ve done for centuries with animals and agriculture.”
Link for the recent research report in above reference:
http://www.wired.com/wiredscience/2012/01/evolution-of-multicellularity/
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