1. Development of the Cell Theory Biology 11

2. History Middle ages - magnifying lenses 1590 – first compound microscope Required to view microscopic organisms 1665 – Hooke discovered cells

3. Spontaneous Generation Living organisms could suddenly arise from non-living materials Believed until 19 th century Maggots on rotting meat Frogs & salamanders appear in mud Mushrooms on logs Mice from a dirty shirt & wheat

4. Four Parts of the Cell Theory 1.All living organisms are composed of one or more cells. 2.Cells are the basic units of structure and function in all organisms. 3.All cells are derived from pre-existing cells. 4.In a multicellular organism, the activity of the entire organism depends on the total activity of its independent cells.

5. Asking Questions 500 BC Ancient Greece supports scholars Ask questions about life & nature Seek answers through observations & thought Not experiments

6. Aristotle Greek philosopher 384 – 322 BC 334 BC Classified all living things Plant or animal Believed in spontaneous generation

7. Roger Bacon English philosopher 1214 – 1294 1268 First wrote about eyeglasses

8. Magnifying Images 1590 Dutch eyeglass makers Hans & Zaccharias Janssen Invented first compound microscope Used two lenses Magnified 10x

9. King Charles II English monarch 1602 Founded “Royal Society of London for the Promotion of Natural Knowledge” Shared & debated knowledge Used books, letters, meetings

10. Robert Hooke English scientist 1635 – 1703 1665 Published book – Micrographia Illustrated cork images from microscope Coined term “cells” Empty room-like compartments

11. Antony van Leeuwenhoek Dutch scientist 1632 – 1723 1666/1667 Read Hooke’s book Designed microscopes Six times more magnifying power

12. Francesco Redi Italian scientist 1629 – 1697 1668 Experiments disproved spontaneous generation Maggots do not appear in meat if no contact with flies

13. Redi’s Experiment

14. van Leeuwenhoek (… again!) Wrote letters to Royal Society 1673/1674 Described “animalcules” in water Bacteria & protozoa Hooke later confirmed findings

15. … van Leeuwenhoek (… again!) 1683 Examined plaque from teeth “Many very little living animalcules, very prettily a-moving” Discovered bacteria

16. John Needham English naturalist & priest 1713 – 1781 1748 Experiments supported spontaneous generation

17. John Needham’s Experiment

18. Lazzaro Spallanzani Italian biologist 1729 – 1799 1748 Experiments disproved Needham & spontaneous generation Boiled broth longer

19. 1770’s Microscope mechanical advancements Sturdier & easier to use Not as advanced or clear as van Leeuwenhoek’s

20. Jane Haldiman English science writer 1809 Developed textbooks about science Used terms “cell”, “cellular system”, “cell tissue”

21. Robert Brown Scottish botanist 1773 – 1858 1831 All cells contain a nucleus

22. Matthias Jacob Schleiden German botanist 1804 – 1881 1838 Wrote “All plants are made of cells”

23. Theodor Schwann German physiologist 1810 – 1882 1839 Wrote “All animals are made of cells”

24. Alexander Carl Henrich Braun German botanist 1805 – 1877 1845 Wrote “The cell is the basic unit of life”

25. Jugo von Mohl German biologist 1805 – 1872 1846/1847 Described protoplasm (cytoplasm) and cell membrane

26. William Henry Perkin English chemistry student 1838 – 1907 1856 Developed a purple dye Used to stain slide specimens

27. Rudolph Virchow German physiologist 1821 – 1902 1858 Stated (in short) … “All cells come from pre-existing cells” Disagree with spontaneous generation

28. Louis Pasteur French biologist 1822 – 1895 1860 Finally disproved spontaneous generation Living organisms DO NOT come from non-living matter Prize from Paris Academy of Sciences

29. Louis Pasteur’s Experiment

30. Cell Theory Scientists 1.Schleiden Plants are made up of cells 2.Schwann Animals are made up of cells 3.Virchow All cells come from other cells Indirect Credit: Hooke Discovery of cells van Leeuwenhoek Microscope improvements