The Development of the Cell Theory

1. The Development of the Cell Theory Cell Biology Prepared by: A. Abougabal

2. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 Ancient Times • Ancient peoples are always on the look-out for ways that organisms can be used by them. • Some civilizations support “great thinkers” and philosophers, but they rarely base their thoughts on observation or experiments.

3. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 334 B.C.E - Aristotle • Greek philosopher, Aristotle, begins to observe nature. • He classifies all known organisms as either a Plant or and Animal. • He writes that living things can arise spontaneously from non-living matter.

4. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 1268 – 1st Eyeglasses • Roger Bacon, an English friar makes reference to a pair of eye glasses. • This means that glass is being developed and used in a way that makes it easier to see small things.

5. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 1590 – 1st Microscope • Zacharias Janssen, a Dutch eyeglass maker, makes the 1st microscope by placing two lenses on top of one another to make extra-large images.

6. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 1600’s • People start to question the origins of life. • Many begin to suggest that life can only come from other forms of life rather than through spontaneous generation (as was suggested by Aristotle). This only took about 2000 years! • William Harvey says that maggots do not come from the meat itself but from tiny eggs too small to be scene. William Harvey English Physician 1578-1657

7. Cell Theory and the Scientists Who Helped Shape It

8. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 1674 – 1st Microscopic Beasties Seen! • Anton van Leeuwenhoek (1632-1723) reports being able to see tiny beasties (0.002 mm) using a simple single-lens microscope. He is known as the “Father of microscopy.”

9. Anton van Leeuwenhoekhe documented unicellular organisms based on observationsof protozoa [1673] and bacteria [1683]

10. Robert Hooke • Born: July 18, 1635 • Died: March 3, 1703 • Wrote and published “Micrographia” • Known as the “English Father of microscopy” http://www-groups.dcs.st-and.ac.uk/~history/PictDisplay/Hooke.html

11. Robert Hooke Contributions: • [1665] He observed pieces of cork from the bark of a cork tree under the microscope. • His observations led him to coin the word “cell.” -“Cell” means little rooms in Latin http://www.learner.org/channel/courses/essential/life/session1/closer1.html

12. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 1667 – Species Defined • John Ray (1627-1705) defines a “species” as a set of individuals that can reproduce their own kind. • The beginning of the end of spontaneous generation! William Harvey English Physician 1578-1657

13. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 1668 – 1st Experiments about origins of maggots • Francesco Redi (1626-1697)conducts experiments to prove that maggots do not appear in meat if flies cannot land on it! William Harvey English Physician 1578-1657

14. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 1700’s • Microscope claimed to be an instrument of evil when a prominent person was horrified by the sight of a magnified flea! • Scientists begin to doubt spontaneous generation, but the common people still believe in it!

15. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 1770 – Advancement of microscopes • Microscopes become sturdier and easier to use. • Flaws in glass production still causes images to be blurry and have coloured halos.

16. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 1809 – 1st Science Texts for Students • Jane Haldimand (1769-1858) writes textbooks for young people to learn about science. • Terms such as “cell”, “cellular system” and “Cellulartissue” appear in the book.

17. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 1825 – Book “Cells from Cells” • Francois Vincent Raspail (1794-1878) wrote a book called (translated from Latin) “Every cell is derived from a pre-existing cell”.This again puts to rest the idea of spontaneous generation.

18. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 1830 – Cells are studied • Biology is becoming an important science and the body of knowledge is growing, especially since the improvement of microscopes. • Scientists begin to study the cell extensively!

19. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 1831 – Nucleus of Cell Found • Robert Brown (1773-1858) is the 1st to consider the nucleus as a regular part of a living cell. • The nucleus is still hard to see though without the invention of the electric light for his microscope.

20. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 1838 – Plant cells! • Matthias Jacob Schleiden (1804-1881) makes the claim “All plants are made of cells”. • Cells are alive!

21. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 1839 – Animal cells! • Theodor Schwann (1810-1882) makes the claim “All animals are made of cells”. • “All living things are made of cells” • Cells are the basic building blocks of life!

22. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 1845 – Cell Basic Unit of Life • Alexander Carl Heinrich Braun (1805-1877)makes the claim: “The cell is the basic unit of life”. • Cells are made of protoplasm enveloped by a flexible membrane.

23. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 1860’s, The end of the “Spontaneous Generation” debate • Louis Pasteur (1822-1895) • conducts a series of experiments that once and for all put to rest the idea of spontaneous generation and concluding that living organisms do not arise from non-living matter.

24. Who came up with the theory?

25. Major Contributors: • Matthias Schleiden • Theodor Schwann • Rudolph Virchow

26. 1-Rudolph Virchow • German pathologist • He is known as the “Father of Pathology.” Born: October 13, 1821 Died: September 5, 1902

27. Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory 500 BCE 1000 1600 1800 300 BCE 1500 1700 1900 Rudolph wirchowstated “omniscellula a cellula ” [all cells arise from pre-existing cells based on observations of dividing cells [1855] Virchow • Cell Theory • that is still largely accepted today. All cells come from pre-existing cells!

28. proposed that cells were the fundamental units of plantsbased on observations of plant tissue [1838] All plants are made of cells! German botanist 2. Schleiden (1838) Born: April 5, 1804 Died: June 23, 1881 Onion skin cells

29. Plant cells

30. proposed that cells were the fundamental units of animalsbased on observations of animal tissue [1839] Who came up with this theory? All animals are made of cells! 3. Schwann • German zoologist Born: December 7, 1810 Died: January 11, 1882 / Human red blood cells

31. Blood

32. Sperm

33. Schleiden and SchwannThe Cell Theory [1839] • All living things are made of cells. • Cells exhibit the fundamental characteristics of life: • Obtain energy—photosynthesis, chemosynthesis, or digestion • Use energy—respire • Excrete Waste • Show Order • Homeostasis • Evolve • Reproduce • Move • Respond to changes in environment • Grow and repair damage to self

34. The Cell Theory States: • As written by Rudolph Virchow (1821-1902): • All living organisms are made of one or more cells. • Cells are the basic units of structure and function in all organisms. • All cells come from previously existing cells. • The activity of an entire organism depends on the total activity of its independent cells.

35. Definition = Three part theory about cells 1. All living things are made of cells.

36. Part 2 of the Theory 2. The cell is the basic structural and functional unit of life.

37. Part 3 of the Theory 3. All cells come from pre-existing cells. yeast cells dividing

38. How big are cells? • Microscopic (mostly) • Measured in microns µm • (micrometers). • A µm is one millionth of a meter = • 10-9 m = one thousandth of 1 mm.

39. How big are cells? Smallest free-living cell = Mycoplasma genitalium Size = 0.2 to 0.3 µm

40. How big are cells? • Bacteria e.g. Eschericia coli (aka E.coli) • Size=1 µm by 3 µm

41. How big are cells? • Human red blood cell = • 8 µm in diameter

42. How big are cells? • Largest cell on the human body = ovum • Size= • 1000 µm in diameter (1 mm)

43. How big are cells? • Smallest cell in the human body = sperm cell.

44. How can we study cells? Problem: They are microscopic! Solution: Use a microscope!

45. Cell biology • Cell biology is the study of cell structure and function, and it revolves around the concept that the cell is the fundamental unit of life. • Focusing on the cell permits a detailed understanding of the tissues and organisms that cells compose. • Some organisms have only one cell, while others are organized into cooperative groups with huge numbers of cells. • On the whole, cell biology focuses on the structure and function of a cell, from the most general properties shared by all cells, to the unique, highly intricate functions particular to specialized cells.

46. Microscopes

47. A. COMPOUND MICROSCOPE • Compound light microscope • Light passes through lenses to magnify image up to 1000X • Can observe living cells

48. Human Cheek Cell Nerve Cells Light Microscope

49. B. STEREOMICROSCOPE • Gives 3D images ofspecimen

50. C. SCANNING ELECTRON MICROSCOPE (SEM) • Uses electrons instead of light to project surface image of specimen