The Cell TheoryMicroscopes Provide the Windows to the World of the Cell

Anton Van Leeuwenhoek

(1600’s)

Credit for the first microscope

Looked at pond water and saw “wee beasties”

Robert HookeObserved plant stems, wood, and cork (1600’s)

He used a compound scope (series of lenses)

He was the first to use the term “cell”

What cell part did Hooke observe?

Cell Wall

Robert Brown (1833)

Observed that cells had a dark structure within plant cells

Brown observed the nucleus

Matthias Schleiden (1838)

Stated that all plants are made of Cells

Made many observations of plants around the area

Theodor Schwann (1839)

Stated that all animals are made of Cells

Observed many animal tissues

Rudolf Virchow (1855)Stated that all cells come from pre-existing cells

Cells arise from the division of pre-existing cells

Louis Pasteur (1859)Disproved the Theory of Spontaneous Generation

Cell TheoryCell Theory is the unifying theme in biology because it emphasizes the similarity of all living things

All organisms are composed of one or more cells.Cells are the smallest living units of all living organisms.Cells arise only by division of a previously existing cell.

Exceptions to the Cell Theory

Viruses – are not cellular

Mitochondria and chloroplast – each contain genetic material and can reproduce