The Cell Theory After the invention of the microscope, many groundbreaking discoveries were made in the field of life sciences. Robert Hooke discovered the cell in 1665. In 1674, Antonie Van Leeuwenhoek described the first
single-celled organism, bacterium. In 1678, Leeuwenhoek reported the observation of “little animals,” or protozoa, in a water sample. In 1838, Matthias Jakob Schleiden, a German botanist who used a microscope to study plants, stated that all the parts of plants are composed of cells. When Schleiden mentioned his observation to his physiologist friend Theodor Schwann, Schwann realized that he had
seen a similar structure in animals. Together, they put forth what is now known as the cell theory. It states that: • every living organism is made of cells. • the cell is the basic unit of life. • all cells arise from preexisting cells. Characteristics of Cells • Every cell has its own organs called organelles. • All cells can grow, divide, and die. • Cells have genetic material that stores information. Types of Cells
Cells are of differing sizes and shapes, and they perform varied functions. However, the basic components of all cells are the same. Each body part is made up of a specific type of cell depending on the functions it performs. Bone cells are rigid and help shape our bodies, while red blood cells are flexible and carry oxygenated blood to various organs. Nerve cells are long, thin, and narrow, whereas muscle cells are rod-shaped.
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