Cell Theory

• Cell Theory


  Describes where the term “cell” and the other basic information about the cell came from
• Cell is the basic unit of life
• Cell is the building block of all organisms
• Unicellular organisms


  Organisms made up of only one cell
• Multicellular organisms


  Organisms composed of many cells
• Even the life of a very huge multicellular organism

  Begins with a single cell – a sperm cell and an egg cell
• The idea about the cell came up as a result of different studies conducted by several biologists from different countries of the world for about 300 years
• Schleiden and Schwann


  Proposed that all living things are made up of cells
• Rudolf Virchow concluded that all living cells come from preexisting cells
• Hans and Zacharias Jansen made the first simple microscope


  1590
• Matthias Schleiden stated that all plants are composed of cells


  1838
• Theodore Schwann concluded that all animals are composed of cells


  1839
• 3 Cell Theories

  1. All organisms are composed of one or more cells
  2. The cell is the basic unit of life all living things
  3. Cells are produced by the division of pre-existing cells
• 1670

  • Antoine Van Leuwenhoek, Father of Microscopy and Microbiology
  • used microscope containing improved lenses that could magnify objects almost 300x
  • he found "motile" objects under a microscope
  • observed sperm cells, red blood cells, bacteria, and a myriad of single-celled organisms in pond water after his invention of a more powerful microscope
  • a nucleus was observed within some of the red blood cells.
  • "vorticella" a free cells
  • he named these "animalcules", which included protozoa and other unicellular organisms like bacteria

  
• 1665

  • Robert Hooke
  • discovery and first observation of the cell
  • gave the term “cell” for the box-like structures observed in a very thin slices of cork tissue under the microscope
  • observed that the piece of cork was composed of many tiny compartments which resembled little rooms surrounding wall.
  • came from the latin word cella meaning "a small room" like where monks lived in
  • Cellulae means the six-sided cell of a honeycomb

  
• 1831

  • Robert Brown
  • saw a central structure in plant cells, called this structure a nucleus
• 1838

  • Matthias Schleiden
  • suggested that plants are composed of cells
• 1839

  • Theodore Schwann
  • suggested that animals are composed of cells (different shapes)
• 1858

  • Rudolf Virchow
  • suggested that cells came from pre-existing cells
• Modern Cell Theories

  • All organisms are composed of one or more cells.
  • The cell is the basic unit of life of all living things
  • All cells arise from pre-existing cells.
  • Cells contain hereditary information (DNA) that is passed from cell to cell during cell division.
  • cell are basically the same in chemical composition (carbon)
  • all energy flow of life occurs within the cells