Download Robert Hooke (1665) saw cells while looking at a piece of cork

Robert Hooke (1665) saw cells while looking at a piece of cork under the microscope.
Anton Von Leeuwenhoek (1673) saw animalcules (“little animals”) in pond scum.
Theodor Schwann (mid 1800’s)
Cell Theory:
1. all organisms are composed of one or more cells.
2. the cell is the basic unit of life in all living things.
Added by Rudolf Virchow in 1858:
3. all cells come from existing cells.
Cell membrane – protective barrier that controls the passage of material into and out of
the cell.
Organelles – structures that enable the cell to live, grow, and reproduce.
Cytoplasm – cellular fluid
Nucleus – membrane covered organelle that holds the DNA
Prokaryotic –
simple cells (oldest fossils have prokaryotic bact. 3.5 billion years old)
no nucleus
no membrane covered organelles
circular DNA
Bacteria
Eukaryotic –
Nucleus
Membrane-covered organelles
Linear DNA
All other cells