Cells Unit
Cell = the smallest unit that can carry on all the processes of life
Discovery of the Cell
- made possible by development of the microscope
- Hooke = examined thin slices of cork; called spaces cells
- actually looked at dead plant cells
- van Leeuwenhoek = 1st person to observe living cells
- Schleiden = concluded that all plants are composed of cells
- Schwann = concluded that all animals are composed of cells
- Virchow = reasoned that cells only come from other cells
Cell Theory
1) All living things are composed of one or more cells
2) Cells are the basic units of structure and function in an organism
3) Cells come only from the reproduction of existing cells
Cell Diversity
- cells are limited in size by their surface area to volume ratio
- at some point, a cell can’t take in enough energy quickly enough to live
- organelles = cell components that perform specific functions for the cell
- two types: eukaryotes and prokaryotes
Eukaryotes
Prokaryotes
Cell Membrane
Cytoplasm
Ribosomes
Nucleus
Membrane-bound organelles
Largest
Single or Multi Celled
ex: plants, animals
Cell Membrane
Cytoplasm
Ribosomes
No Nucleus
No membrane-bound organelles
Smallest
Single Celled
ex: bacteria
Multicellular Organization
Cells  Tissues  Organs  Organ Systems  Organism
(smallest)
(simple)
(largest)
(complex)