Characteristics of Life Organization The ability to grow and develop The ability to respond to the environment The ability to reproduce

Theory A theory is a widely accepted explanation of things observed in nature. Theories are important because they serve as foundations for further research and study, and can lead to research that is beneficial to society.

Cell Theory Every living thing is made of cells. The cell is the basic unit of structure and function of all living things. Cells come only from other living cells by cell division.

The Giants of Cell Theory Robert Hooke Looked at cork under a microscope and saw “little rooms” that he named as cells. Published his book Micrographia in 1665 Based his prior knowledge on other people’s theories that were not tested. Anton van Leeuwenhoek In 1673 he looked at a drop of pond water under a microscope and saw “wretched beasties” that we now call microbes. Based his prior knowledge on Hooke’s book

The Giants of Cell Theory Matthias Jacob Schleiden In 1838 he suggested that all plants are made of cells. Based his prior knowledge on Hooke’s work Theodor Schwann In 1839 he suggested that all animals are made of cells. Based his prior knowledge on Schleiden’s work

The Giants of Cell Theory Rudolf Carl Virchow Famous for saying in the 1850’s: “All cells arise from cells.” Based his prior knowledge on the work of Schleiden and Schwann Louis Pasteur In 1864 he began studying microbes and noticed that certain ones could cause food and drink to spoil. He discovered that heat would kill these microbes. Using heat to kill microbes is called pasteurization.