1. An introduction to the cell Section 7.1
What is a cell?
An introduction to the cell
Section 7.1

2. A Cell Is…. the basic unit of life
the smallest division of an organism that is still considered to be alive
a cell has all 5 characteristics of life; produce offspring, growth & development, orderly structure, adapt to changes in environment, and adapt and evolve
a cell’s basic parts are cytoplasm, DNA/RNA, and plasma membrane
Some also contain organelles—a membrane bound structure that has a particular function in the cell
Hierarchy—cells from tissues—tissues form organs—organs form organ systems—organ systems form organism

3. Hierarchy
CELLS ↓
TISSUES
ORGANS
ORGAN SYSTEM
ORGANISM

4. Discovery
The invention of the microscope lead to the discovery of the cell.
Anton van Leeuwenhoek invented the first light microscope
Robert Hooke discovered the cell using a compound light microscope.

5. Microscopes
Compound Light Microscope: uses a series of lenses to magnify objects up to 1500 times.
Electron Microscope: uses a beam of electrons to magnify up to 500,000 times
Types of Electron Microscopes:
Scanning Electron Microscope: shows a 3-D shape
Transmission Electron Microscope: shows the structures on the inside of the cell

6. THE CELL THEORY The cell is the basic unit of life
All organisms are composed of one or more cells
Cells come from pre-existing cells
Contributors to the cell theory: Hooke, Schliden, and Schwann.

7. Types of Cells Prokaryotic—has no membrane bound organelles
Eukaryotic—has membrane bound organelles

8. Types of Cells
Nucleus: organelle in eukaryotic cells that controls the cellular functions
Robert Brown: discovered the nucleus