STRUCTURE AND FUNCTION OF THE CELL

I.  All Organisms are Made of Cells

A. The cell is the basic unit of structure & function

B. The cell is the smallest unit that can still carry on all life processes

C. Both unicellular (one celled) and multicellular (many celled) organisms are composed of cells

D. Before the 17^th century, no one knew cells existed

E. Most cells are too small to be seen with the unaided eye

F. In the early 17^th century microscopes were invented & cells were seen for the 1^st time

G. Anton Von Leeuwenhoek, a Dutchman, made the 1^st hand-held microscope & viewed microscopic organisms in water & bacteria from his teeth. His microscope was very simple, but his skill at grinding lenses made it superior to many of the compound microscopes used previously.

                    

                                 

H. In 1665, an English scientist named Robert Hooke made an improved microscope, was the first to supply a light source to the viewing area.  and viewed thin slices of cork viewing plant cell walls

I. Hooke named what he saw "cells"

 

J. In the 1830’s, Matthias Schleiden (botanist studying plants) & Theodore Schwann (zoologist studying animals) stated that all living things were made of cells

K. In 1855, Rudolf Virchow  hypothesized that cells divide to form new cells. He stated that cells only arise from pre-existing cells

L. Virchow’s idea contradicted the idea of spontaneous generation (idea that nonliving things could give rise to organisms)

M. The combined work of Schleiden, Schwann, & Virchow is known as the Cell Theory.

 

II. Principles of the Cell Theory

A. All living things are made of cells

B. Cells are the basic unit of structure & function in living things.

C. Living cells come only from other living cells.