Cell theory promoted the study of cells and the field of cell biology and microbiology.

Starting with Robert Hooke’s imaging of cork cells with a microscope in the 1600s, the microscope opened up the world of life at the level of the cell. The pioneering scientific work of Schleiden, Schwann, and Virchow made them the founders of the unified cell theory in the 1800s. As microscopes continued to improve, more discoveries encompassed the cells of living things, and the cell theory became more profound.

However, by the late 1800s, light microscopes had reached their limit. Objects much smaller than cells, including the structures inside cells, were too small to be seen in a light microscope. Then, in the 1950s, the electron microscope was invented that enabled scientists to observe tiny objects. They could even see individual molecules and atoms. It allowed scientists to study organisms at the level of their molecules and led to the emergence of the field of microbiology and molecular biology.

The development in the technology of microscopes promoted the evolution of the unified cell theory to give us a modern understanding of cells. The modern cell theory evolved our knowledge by identifying that: cells carry genetic material passed to daughter cells during cellular division. All cells are mostly the same in chemical composition and metabolic activities. All basic biochemical & physiological functions (movement, digestion, etc.) are carried out inside the cells. That cell activity depends on the activities of sub-cellular structures (organelles, nucleus, plasma membrane) within the cell.

This advancement in the understanding of cells has impacted nearly every aspect of biology, from the understanding of life and death to managing diseases, and more. Research in cell biology plays a big part in other fields such as genetics, molecular genetics and biochemistry.

Key Points

• The invention of the electron microscope allowed scientists to study organisms at the level of their molecules and led to the emergence of the field of microbiology and molecular biology.

• Cell theory promoted the cell biology that studies the structure and function of the cells; it affects nearly every aspect of biology, from the understanding of life and death to managing diseases, and more.

Key Terms

electron microscope: a microscope with high magnification and resolution, employing electron beams in place of light and using electron lenses

molecular biology: the branch of biology that deals with the structure and function of the macromolecules (e.g. proteins and nucleic acids) essential to life

unified cell theory: The scientific theory that all living organisms are made of cells as the smallest functional unit.

Robert Hooke: a 17th-century scientist who imaged cork through a microscope lens and discovered cells

light microscope: uses visible light and a system of lenses to generate magnified images of small objects

microbiology: the study of microscopic organisms, such as bacteria, viruses, archaea, fungi and protozoa

metabolic: the whole range of biochemical processes that occur within a living organism.