The Cell — Organelles and Who Discovered What

Discovery and the Cell Theory

• ›Robert Hooke, 1665 — first observed cells in a thin slice of cork and coined the word *cell*. He saw dead cell walls, not living cells
• ›Anton van Leeuwenhoek, 1674 — first saw living cells (bacteria, protozoa)
• ›Robert Brown, 1831 — discovered the nucleus
• ›Purkinje, 1839 — coined the term protoplasm
• ›Schleiden and Schwann, 1838–39 — proposed the Cell Theory
• ›Rudolf Virchow, 1855 — added that all cells arise from pre-existing cells (*omnis cellula e cellula*)

Cell Theory in three points: all living things are made of cells; the cell is the basic structural and functional unit of life; all cells come from pre-existing cells.

Size extremes: smallest cell — Mycoplasma (~0.1 µm). Largest cell — an ostrich egg. Longest cell — a nerve cell.

1. Who coined the term "cell" after observing a thin slice of cork?

2. Which organelle is called the "suicide bag" of the cell?

3. Which of the following is present in plant cells but absent in animal cells?

4. The nucleus was discovered by:

5. The cell wall of a plant cell is mainly composed of:

6. Which statement about prokaryotic cells is correct?

7. Movement of water molecules across a semi-permeable membrane is called:

8. Mitochondria are called semi-autonomous organelles because they: