AP BIOLOGY

Detailed explanation-1: -The classical cell theory was proposed by Theodor Schwann in 1839. There are three parts to this theory. The first part states that all organisms are made of cells.

Detailed explanation-2: -First, Schwann concluded that both plants and animals were composed of cells. Second, these cells have independent lives. Third, these independent lives are subject to the organism’s life.

Detailed explanation-3: -His research led to the discovery of the cell that produces the myelin sheath that envelops the axon. In honor of his contribution, this was later eponymously named the Schwann cell [3, 7, 9]. He also found that during embryonic development individual cells unite to form the muscle fiber [10].

Detailed explanation-4: -By the late 1830s, botanist Matthias Schleiden and zoologist Theodor Schwann were studying tissues and proposed the unified cell theory. The unified cell theory states that: all living things are composed of one or more cells; the cell is the basic unit of life; and new cells arise from existing cells.

Detailed explanation-5: -Matthias Jacob Schleiden was a German botanist who, with Theodor Schwann, cofounded the cell theory. In 1838 Schleiden defined the cell as the basic unit of plant structure, and a year later Schwann defined the cell as the basic unit of animal structure.