7.1 Cell Discovery and Theory

Main Idea: The invention of the microscope led to the discovery of cells.

Section Summary

• Microscopes have been used as tools for scientific study since the late 1500s.
• Scientists use different types of microscopes to study cells.
• The cell theory summarizes three principles.
• There are two broad groups of cell types: prokaryotic cells and eukaryotic cells.

History of the Cell Theory

• In 1665, Robert Hooke made a simple microscope.
• Cell: The basic structural and functional unit of all living organisms.
• In the late 1600s, Anton Van Leeuwenhoek designed his own microscope.

The Cell Theory

• Fundamental idea of modern biology that includes these three principles:
  • All living organisms are composed of one or more cells.
  • Cells are the basic unit of structure and organization of all living organisms.
  • Cells arise only from previously existing cells, with cells passing copies of their genetic material on to their daughter cells.

Microscope Technology

• Compound Light Microscope
  • Utilizes a series of glass lenses and visible light to produce a magnified image.
  • Maximum magnification is around x1000.
• Electron Microscope
  • Utilizes magnets to aim a beam of electrons at a cell to produce images.
  • Specimens must be nonliving.
  • Magnifies images up to x500,000.

Basic Cell Types

• Cells exists in various shapes and sizes.
• Cells differ based on their function they perform for the organism.
• All cells have at least one physical trait in common - the plasma membrane.