Cellular Structures and Functions.Pdf

WHAT IS A CELL? It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The cell is the basic structural and functional unit of all known living organisms. Some organisms are unicellular (made of only one cell) while others are multicellular (made up of several cells). The word cell comes from the Latin cellula, meaning, a small room. The term was coined by Robert Hooke in a book he published in 1665 when he compared the cork cells he saw through his microscope to the small rooms monks lived in. BRIEF HISTORY OF THE CELL THEORY The cell was first discovered by Robert Hooke in 1665. He examined very thin slices of cork and saw a multitude of tiny pores that he remarked looked like the walled compartments of a honeycomb. Because of this, Hooke called them cells, the name they still bear. The first man to witness a live cell under a microscope was Antonie Phillips van Leeuwenhoek, who in 1674 described the algae Spirogyra and named the moving organisms animalcules, meaning "little animals". Leeuwenhoek probably also saw bacteria. In 1839, Theodor Schwann and Matthias Jakob Schleiden suggested that cells were the basic unit of life. In 1858, Rudolf Ludwig Virchow concluded that all cells come from pre-existing cells, thus completing the classical cell theory. Classical Interpretation of the Cell Theory 1. All organisms are made up of one or more cells. 2. Cells are the fundamental functional and structural unit of life. 3. The cell is the unit of structure, physiology, and organization in living things. 4. The cell retains a dual existence as a distinct entity and a building block in the construction of organisms. 5. All cells come from pre-existing cells.
Hand-out 1 in General Biology Unit 2: Cellular Structures and Function

The cell theory holds true for all living things, no matter how big or small, or how simple or complex. Since according to research, cells are common to all living things, they can