Biology: Cell Theory and Early Microscopes

Learning Objectives

• Understand the three fundamental postulates of cell theory: All living organisms are composed of one or more cells, the cell is the basic unit of life, and all cells arise from pre-existing cells.
• Identify the structure and roles of major organelles (like the nucleus and mitochondria) and subcellular components (such as ribosomes and endoplasmic reticulum).

The Early Microscope

• Hans Janssen and Zacharias Janssen invented the first compound microscope, combining two lenses for enhanced viewing.
• The eyepiece lens magnified the image, while the second lens was positioned near the specimen for improved observation.
• This design laid the foundation for modern optical microscopy.

17th Century Microscopes and the Discovery of the Cell

• Robert Hooke advanced microscope technology further and is celebrated as the English Father of Microscopy.
• He observed and named the cell, derived from the Latin word "cella," meaning small room, due to the compartment-like appearance of cork.
• Hooke's observations were of non-living plant cells, marking a pivotal moment in the understanding of biological structures.