module 3

• Cell Theory


  A fundamental theory in biology that states that all living organisms are composed of one or more cells, the cell is the basic unit of structure and function in living organisms, and new cells are created from existing cells
• Discovery of Cell

  1. Hans and Zacharias Janssen

  2. Robert Hooke

  3. Anton/ie van Leeuwenhoek

  4. Matthias Schleiden

  5. Theodor Schwann

  6. Rudolf Virchow
• 1590 Hans and Zacharias Janssen

  -invented the first so-called compound microscope

  in the late 16th century when they

  discovered that, if they put a lens at

  the top and bottom of a tube and

  looked through it, objects on the

  other end became magnified.

  
• 1665 robert hooke

  -In 1665, the English scientist used

  a microscope to examine a thin slice of cork.

  Hooke described it as consisting of “a great many

  little boxes.” These “little boxes” reminded him of

  the cubicles or “cells” in which monks lived in the

  monastery, so he called them cells.

  -What he saw led him to identify the basic unit of

  plant and biological structure, which he called

  the “cell” (from cella, Latin for small chamber).

  -He published Micrographia.

  
• 1673 anton van leeuwenhoek

  -Dutch scientist, he was a

  master microscope maker and perfected the

  design of the simple microscope, enabling it to

  magnify an object by around two hundred to

  three hundred times its original size. What he

  saw with

  these microscopes was bacteria and protozoa,

  but he called these tiny creatures

  “animalcules.”

  -he became fascinated. He went

  on to be the first to observe and describe

  spermatozoa in 1677.

  
• 1838 matthias schleiden

  a German botanist named showed that the development of

  all vegetable tissues comes from the activity

  of cells.

  he believed that cells were “seeded”

  by the nucleus and grew from there.

  
• 1839 theodor schwann

  defined the cell as the basic

  unit of animal structure. they articulated their observations

  as a unified theory—the cell theory—

  which proposed the first two principles

  
• 1855 rudolph virchow

  -German pathologist published biogenic law and coined the

  phrase “omnis cellula e cellular”

  which means cells originate from cells.

  Because of this, he concluded

  that all cells arise from preexisting

  cells, which became the third principle

  of cell theory.

  -He also stated that all diseases involve

  changes in normal cells.
• in 1674 described the algae spirogyra and named the moving organisms animacules