The observation of what was coined the cell by Robert Hooke in 1665 provided the starting point for a sequence of discoveries at the microscopic level and continuing into our present time that have revolutionized our view of life. While Hooke observed the cell by viewing thin layers of cork, it was Antony Van Leeuwenhoek, who can be considered as the first microbiologist, who dramatically expended our view of cellular life.
Contained in the cell are the structural and functional operations of a living organism, making it the basic building block of life. The cell membrane is the outer most layer of the cell and is composed of a mixture of lipids and proteins. Inside the cell is whats called the cytoplasm, which is a complex mixture of water, salts, enzymes, and other organic molecules or organelles – including the cell nucleus which contains the cells genetic material.
The discovery of the cell lead to the elucidation of a core theory in biology called cell theory, which roughly states that all living organisms are made from basic units called cells that continually reproduce. Within these cells are contained all of the hereditary information as well as a flow of chemical and electrical energy necessary for directing all of the cells activity.