STRUCTURE AND FUNCTION OF CELLS Notes #12

All organisms are made of Cells The cell is the basic unit of structure and function The cell is the smallest unit that can still carry on life processes Unicellular (one-celled) and Multicellular (many celled) organisms are composed of cells Before 17 th century no one knew cells existed

Most cells are too small to be seen with the unaided eye In the early 17 th century, microscopes were invented and cells were seen for the first time All organisms are made of Cells

Important Contributors Anton von Leeuwenhoek –Dutchman –Made the 1 st hand held microscope –Viewed microscopic organisms in water and bacteria from his teeth Leeuwenhoek's microscope consisted simply of: A) a screw for adjusting the height of the object being examined  B) a metal plate serving as the body  C) a skewer to impale the object and rotate it  D) the lens itself, which was spherical

Important Contributors Robert Hooke (1665) –Englishman –Made an improved microscope –Viewed thin slices of cork (dead plant cell walls) –Named what he saw “cells”

Important Contributors Matthias Schleiden & Theodore Schwann (1830s) –All living things were made of cells Rudolf Virchow (1855) –Cells only arise from pre-existing cells –No spontaneous generation

The Cell Theory Combined work of Schleiden, Schwann, & Virchow Principles of the Cell Theory –All living things are made of one or more cells –Cells are the basic unit of structure and function in organisms –Cells come only from the reproduction of existing cells