MadSci Network: Cell Biology |
Rania, This question is more complex than you might first think! I'd like to first refer to a commonly accepted definition of "living thing", which I found in the Free Dictionary online (http://www.thefreedictionary.com/living%20thing) Noun 1. living thing - a living (or once living) entity animate thing organism, being - a living thing that has (or can develop) the ability to act or function independently life - living things collectively; "the oceans are teeming with life" biont - a discrete unit of living matter cell - (biology) the basic structural and functional unit of all organisms; cells may exist as independent units of life (as in monads) or may form colonies or tissues as in higher plants and animals object, physical object - a tangible and visible entity; an entity that can cast a shadow; "it was full of rackets, balls and other objects" viability - (of living things) capable of normal growth and development young, immature - (used of living things especially persons) in an early period of life or development or growth; "young people" By this and many other definitions, a single cell from a multicellular organism is indeed a living thing. It is able to sustain itself and contains all resources necessary to replicate itself (or can obtain them as nutrients from it's environment). As you have probably learned, the cell is the most basic unit of life, and is thus the simplest "thing" which can be properly called a living thing. This question becomes more complex when you consider the nature of some entities which cause disease -- for example, viruses. Viruses are incapable of replicating themselves, even if given nutrients. They require the proteins and structures within cells in order to make more of themselves. So are they living things? Even most scientists cannot agree on the answer to this question. Lots to think about! I hope that this helps, and that you're always curious about science -- good luck!
Try the links in the MadSci Library for more information on Cell Biology.