7th Microscopy and the Development of Cell Theory

First Compound Microscope

Janssen design from 1590

Focuses by sliding the outer tube; maximum magnification of 10x

Microscope used by Robert Hooke in the discovery of “cellulae” (cells)

A lens focuses light from the flame in the oil lamp onto the specimen. Yielded poor images and magnification of about 30x. (simulation – magnification and resolution)

Hooke’s drawings of cork cells.

About Cork: http://home.howstuffworks.com/question550.htm

Cellulae means little storage rooms in Latin

Anton Van Leeuwenhoek – Father of Microbiology and Inventor of the

1st microscope to magnify beyond 50x

The entire instrument was only 3-4 inches long, and had to be held up close to the eye, requiring good lighting and great patience to use.

• Inspired by Robert Hooke’s book, Micrographia.• Royal Society didn’t believe he viewed single-celled organisms so

sent “experts” to dispute the claim – instead, they left in awe over the discovery.

Hans Loncke's recreation of Leeuwenhoek’s microscope

http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artjul07/hl-loncke2.html

Animalcules

“Animalcules,” described in depth by Leeuwenhoek, c1795–1798. By Anton van Leeuwenhoek [Public domain], via Wikimedia Commons.

http://www.answersingenesis.org/articles/aid/v7/n1/antony-van-leeuwenhoek-creation-magnified-microscopes

M.J. Schleiden, a German botanist, concludes that the cell is the “basic building block” of plant

tissues through the aid of microscopes.

Starts a new trend - using microscopes in biological research.

Over dinner in 1838, Schleiden was describing his work to friend Theodor Schwann, who was struck by the similarities seen with his own studies on animals tissues.

His discoveries were published in 1839, a year after Schleiden suggested that plants are made entirely of cells.

Schleiden and Schwann combine their research and propose theCell Theory:

1. Cells are organisms and all organisms consist of one or more cells.

2. The cell is the basic unit of structure for all organisms

Robert Remak observes cells dividing while studying yeast

This a HUGE discovery,

But…

It goes undiscovered for a while until…

Along comes Rudolph Virchow, who in 1855 plagiarizes Remak’s work and wrote that "every cell originates from another existing cell like it."

This idea was added to The Cell Theory.

Modern Cell Theory

1. All living things are composed of cells.

2. Cells are the basic units of structure and function in living things.

3. All cells are produced from other cells.