CELL THEORY Past Present and Future Robert Hooke

CELL THEORY: Past , Present and Future

Robert Hooke ØCoined the term “cell”

Matthias Schlieden ØCells can move and are ALIVE!

Anton van Leeuwenhoek ØFirst compound light microscope

Theodor Schwann ØAll plants and animals are made of many million cells

Rudolf Virchow ØCells can only arise from preexisting cells

Cell Theory The cell is the basic unit of life. 2. All living things are made of one or more cells. 3. All cells arise from preexisting cells. 1.

Prokaryote vs. Eukaryote Ø Prokaryotes= Cells WITHOUT a cell nucleus l l DNA floats freely in the cell BACTERIA are prokaryotes (and are very tiny) Ø Eukaryotes= Cells WITH DNA organized into cell nucleus l l All plants, animals, fungi, and protists MUCH larger than tiny prokaryotes

Cell Differentiation: Ø Differentiation: cells becoming specialized to perform different jobs Ø Cell type depends on which genes are turned on or off and when

Ø Stem cells: Cells that are NOT completely differentiated yet Ø Embryonic Stem cells: Come from VERY early embryo and can become anything! Ø Adult Stem cells: from only a few “niches” and can only become a limited number of cell types. Ex. Bone marrow stem cells = 5 types of blood cells

Questions. . . Ø Who used the first microscope? Ø Who said that plants were made of cells Ø Who coined the term “cell”? Ø Who said that all animals were made of cells? Ø Who said that cells must come from existing cells?

State the cell theory. . . n. ALL organisms are made of one or more cells. n. The cell is the basic unit of structure and function in an organism. n. All cells arise from pre-existing cells.