Cell Theory

• Cell, in biology, is the basic membrane-bound unit that contains the fundamental molecules of life and of which all living things are composed
• A cell the smallest living organism and the basic unit of life on earth
• Cell biology - A branch of biology that focuses on the study of cells, their structure, function, and life processes. It involves the examination and analysis of cells, including their organelles and other cellular components, to understand the fundamental principles governing life at the cellular level
• A microscope is an optical instrument that is used to magnify and observe objects that are too small to be seen with the naked eye. It enables scientists, researchers, and students to study the details of tiny structures, such as cells, microorganisms, and small particles, by making them appear larger and more visible
• The cell theory is a fundamental scientific theory of biology according to which cells are held to be the basic units of all living tissues
• In 1665, Robert Hooke published Micrographia, a book filled with drawings and descriptions of the organisms he viewed under the recently invented microscope.
• The invention of the microscope led to the discovery of the cell by Hooke.
• In 1676, Antonie van Leeuwenhoek who is a Dutch scientist discovered bacteria and protozoa which he called animalcules.
• Antonie van Leeuwenhoek is often referred to as the "Father of Microbiology" due to his groundbreaking observations using simple microscopes of his own design.
• In 1838, Matthias Schleiden who is a German botanist proposed that the basic unit of all plant tissues was the cell.
• In 1839, Theodor Schwann, building on the work of Matthias Schleiden, extended the cell theory to animals.
• In 1858, Rudolf Virchow, a German physician, pathologist, and anthropologist, who was credited with the third key principle of the cell theory: Omnis cellula e cellula (All cells come from pre-existing cells).
• Modern Cell Theory:

  1. All living organisms are made up of cells.
  2. Cells are the basic unit of life.
  3. Cells come from pre-existing cells.
  4. The genetic material is contained in the cell.
  5. Energy flow occurs within the cell.
  6. Cells of all organisms in the same species are mostly the same, both structurally and chemically.