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: -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-3: -Schwann also discovered pepsin, the first animal enzyme known, and revealed that yeast is a living organism. All of his discoveries were made between 1834 and 1839, before he was 30 years old.

Detailed explanation-4: -Both Schleiden and Schwann studied cell theory and phytogenesis, the origin and developmental history of plants. They aimed to find a unit of organisms common to the animal and plant kingdoms. They began a collaboration, and later scientists often called Schleiden and Schwann the founders of cell theory.

Detailed explanation-5: -In it Schwann declared that “All living things are composed of cells and cell products". He drew three further conclusions about cells, which formed his cell theory or cell doctrine. The first two were correct: The cell is the unit of structure, physiology, and organization in living things.