Cell Basics
The cell is the most basic unit of life capable of carrying out all activities necessary for survival. Though microscopic, these tiny structures are incredibly complex and exist in two main types: eukaryotic and prokaryotic.
The discovery of cells happened gradually through the work of several scientists. Robert Hooke first observed cells in 1665 while examining cork, describing them as "boxes." Later, Anton Van Leeuwenhoek observed living cells in pond water (1673), which he called "animalcules." Scientists Theodore Schwann and Mattias Schleiden further established that both animal and plant tissues contained cells. Rudolf Virchow ultimately proposed that cells come from other preexisting cells.
These discoveries led to the Cell Theory, which has three main principles: every living organism consists of one or more cells; the cell is the basic unit of structure and function; and all cells arise from preexisting cells.
Quick Fact: The word "cell" comes from the Latin word "cella," meaning small room or chamber, which is exactly what Robert Hooke thought he was seeing when he first observed cork cells!
All cells share common features despite their diversity. These include ribosomes (protein factories), cytoplasm (the fluid inside cells), DNA/RNA (genetic material), and a cytoskeleton (internal framework). The cell membrane, made of phospholipids, forms the outer boundary and controls what enters and exits the cell.