Biology Chapter 7, Section 1

• -he made a microscope & looked at a piece of cork.
• -he observed box like structures he called cells.

The work of Hooke & other scientists led to the cell theory, which consists of the following 3 principles:

• 1. All living things are made up of one or more cells.
• 2. Cells are the basic unit of structure & orhanization of all living things.
• 3. Cells arise from other pre-existing cells.

• -cells come in different shapes & sizes.

• -scientists have grouped cells in 2 categories.

• Prokaryotic Cells
• -cells without a nucleus
• -without membrance-bound organelles.
• -unicellular-bacteria.

• Eukaryotic Cells
• -cells with a nucleus.
• -contains membrane-bound organelles.
• -unicellular or multicellular.

Organelles are specialized structures that preform specific functions for the cell.