Cells are the fundamental units of all living things. They got their name from Robert Hooke who observed magnified cork cells that resembled monks' living quarters called cells. All cells share some basic features including cytoplasm, a cell membrane boundary, metabolic life processes, DNA, and ribosomes. Cells are classified as prokaryotes or eukaryotes, with prokaryotes being smaller bacteria and archaea without nuclei, and eukaryotes being larger animal, plant, fungi and protist cells with nuclei and organelles.

1. Cell Structure Cells are the fundamental units of all living things. They got their name when Robert Hooke viewed some magnified cork cells and thought they resembled the austere living quarters of monks, which were called cells.

2. (Photo of Hooke’s public domain drawing and the cork oak bark photo uploaded to Flickr and the latter licensed under Creative Commons by Martin LaBar, the monk’s cell uploaded to Flickr and licensed under Creative Commons by Vittis from Lithuania)

3. All cells share some basic features: All have cytoplasm - the living substance. All have a cell or plasma membrane which contains the cytoplasm and provides a boundary defining the border between the cell and its environment, while still allowing some materials to enter or leave.

4. All have life processes called metabolism, which take place within this boundary.

5. All have DNA, the hereditary material.

6. All have ribosomes, which are organelles necessary for the synthesis of proteins.

7. All living cells may be classified into two basic types: prokaryotes and eukaryotes.

8. Prokaryotes are represented by two groups: 1. Archaea (or Archaebacteria) 2. Bacteria. (or Eubacteria) Eukaryotes include all other cells: animals plants fungi protists.

10. Prokaryotes are much smaller than eukaryotes: 0.1-10 um, (hundreds would fit on the point of a pin) Eukaryotes are much larger, with diameters from 10-100 um.

11. Prokaryotes have no nucleus. Eukaryotes have a nucleus and membranous organelles. Prokaryotes generally have cell walls Eukaryotes may have cell walls, depending on the type of cell: animals don’t, plants do

12. The diagrams shown illustrate the major internal structures or organelles and their relationships to each other.

13. Plant & animal cells compared You should study these diagrams of the cells and learn to recognize the labeled parts so that you will be able to label the diagrams yourself. This URL may help: http://www.forgefx.com/casestudies/prenticehall/ph/cells/cells.htm