Cells

Period 2. **1c. **
 * Stephanie Gutierrez.
 *  Students know ****how prokaryotic cells, eukaryotic cells (including those from plants and animals), and viruses differ in complexity and general structure ** **

The **cell** is the functional basic unit of life. It was discovered by [|Robert Hooke] and is the 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.[|[1]] Some organisms, such as most[|bacteria], are [|unicellular] (consist of a single cell). Other organisms, such as [|humans], are[|multicellular]. (Humans have about 100 trillion or 1014 cells; a typical cell size is 10 [|µm]; a typical cell mass is 1 [|nanogram]. The largest cells are about 135 µm in the [|anterior horn in the spinal cord]while [|granule cells] in the [|cerebellum], the smallest, can be some 4 µm and the longest cell can reach from the toe to the lower [|brain stem] ([|Pseudounipolar cells]).[|[2]]) The largest known cells are unfertilised [|ostrich] [|egg cells] which weigh 3.3 pounds.[|[3]][|[4]] 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.[|[5]] 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.[|[6]]