Who Discovered the Cell?

• Prior to scientific research:– People thought disease was caused and cured by

supernatural beings

Robert Hooke (1665)• Hooke observed a wide diversity of

organisms including insects, sponges, bryozoans, diatoms, and bird feathers.

• Robert Hooke coined the term “cell", in a biological context, as he described the microscopic structure of cork like a tiny, bare room or monk's cell in his landmark discovery of plant cells with cell walls.

• Hooke was able to confirm Leeuwenhoek's surprising observations of bacteria and protozoans, leading to the general acceptance of the Dutch scientist's results by the established scientific community.

Cork Cells

The eyes of a fly drawn by

Robert Hooke

Anton von Leeuwenhoek (1632-1723)

• Began viewing specimens using a magnifying glass.

• He then used multiple glasses to further increase the magnification.

• During his lifetime he made over 247 microscopes.

• After an accidental discovery of what he called “animalcules” he provided the first complete descriptions of what later came to be collectively called bacteria.

Light Microscope

• 1600’s 2 lens were combined

• Over next 200 years this was improved

• Up to 1500x magnification– Limited by

wavelength of light

• Robert Brown (1831) - discovered the structure of the nucleus.

• Noticed that every plant cell had an opaque spot he thought to be insignificant

• He then found that every cell had this spot, even pollen and newly formed cells

Schleiden & Schwann (1839)

• Together developed the “Cell Theory” which identified cells as the fundamental particles of plants and animals.

• They recognized that some organisms are unicellular and others multicellular.

• They also recognized common cell features and described them by comparison of various animals and plants.

Electron microscopes

• Developed in the 1930’s

• Was able to magnify specimens 500,000x

• This allowed for study of the organelles

Algae and bacteria 5,000x

Historical Background

• Improvement in microscopes in the last four centuries has allowed scientists to better develop the cell theory.