2. AP Biology The Cell Theory

3. AP Biology Some Random Cell Facts  The average human being is composed of around 100 Trillion individual cells!!!  It would take as many as 50 cells to cover the area of a dot on the letter “ i ” WOW!!!

4. AP Biology Discovery of Cells  1665- English Scientist, Robert Hooke, discovered cells while looking at a thin slice of cork.  He described the cells as tiny boxes or a honeycomb  He thought that cells only existed in plants and fungi

5. AP Biology Anton van Leuwenhoek  1673- Used a handmade microscope to observe pond scum & discovered single-celled organisms  He called them “animalcules”  He also observed blood cells from fish, birds, frogs, dogs, and humans  Therefore, it was known that cells are found in animals as well as plants

6. AP Biology 150-200 Year Gap???  Between the Hooke/Leuwenhoek discoveries and the mid 19 th century, very little cell advancements were made.  This is probably due to the widely accepted, traditional belief in Spontaneous Generation.  Examples: -Mice from dirty clothes/corn husks -Maggots from rotting meat

7. AP Biology 19 th Century Advancement  Much doubt existed around Spontaneous Generation  Conclusively disproved by Louis Pasteur Pasteur: Ummm, I don’t think so!!! + = ?

8. AP Biology Development of Cell Theory  1838- German Botanist, Matthias Schleiden, concluded that all plant parts are made of cells  1839- German physiologist, Theodor Schwann, who was a close friend of Schleiden, stated that all animal tissues are composed of cells.

9. AP Biology Development of Cell Theory  1858- Rudolf Virchow, German physician, after extensive study of cellular pathology, concluded that cells must arise from preexisting cells.

10. AP Biology The Cell Theory Complete  The 3 Basic Components of the Cell Theory were now complete:  1. All organisms are composed of one or more cells. (Schleiden & Schwann)(1838-39)  2. The cell is the basic unit of life in all living things. (Schleiden & Schwann)(1838-39)  3. All cells are produced by the division of preexisting cells. (Virchow)(1858)

11. AP Biology Modern Cell Theory  Modern Cell Theory contains 4 statements, in addition to the original Cell Theory:  The cell contains hereditary information(DNA) which is passed on from cell to cell during cell division.  All cells are basically the same in chemical composition and metabolic activities.  All basic chemical & physiological functions are carried out inside the cells.(movement, digestion,etc)  Cell activity depends on the activities of sub- cellular structures within the cell(organelles, nucleus, plasma membrane)

12. AP Biology How Has The Cell Theory Been Used?  The basic discovered truths about cells, listed in the Cell Theory, are the basis for things such as:  Disease/Health/Medical Research and Cures(AIDS, Cancer, Vaccines, Cloning, Stem Cell Research, etc.)

13. It’s all about: Surface Area-to-Volume Ratio Cell radius (r) 1 unit 10 units Surface area (4 ╥ r 2 ) 12.57 units 2 1257 units 2 Volume(4/3 ╥ r 3 ) 4.189 units 3 4189 units 3 Large Cells vs. Small Cells Why Are Cells So Small? Size Matters! As a cell get larger, its volume increases at a faster rate than its surface area! SA/V= 2.98 0.30 ______

14. AP Biology Archaebacteria & Bacteria Classification  Old 5 Kingdom system  Monera, Protists, Plants, Fungi, Animals  New 3 Domain system  reflects a greater understanding of evolution & molecular evidence  Prokaryote: Bacteria  Prokaryote: Archaebacteria  Eukaryotes  Protists  Plants  Fungi  Animals Prokaryote Eukaryote

15. AP Biology Kingdom Protist Kingdom Fungi Kingdom Plant Kingdom Animal Kingdom Archaebacteria Kingdom Bacteria

16. AP Biology 2007-2008 Prokaryotes Domain Bacteria Domain Archaebacteria Domain Bacteria Domain Archaea Domain Eukarya Common ancestor

17. AP Biology Bacteria live EVERYWHERE!  Bacteria live in all ecosystems  on plants & animals  in plants & animals  in the soil  in depths of the oceans  in extreme cold  in extreme hot  in extreme salt  on the living  on the dead Microbes always find a way to make a living!

18. AP Biology Bacterial diversity rods and spheres and spirals… Oh My!

19. AP Biology Prokaryote Structure  Unicellular  bacilli, cocci, spirilli  Size  1/10 size of eukaryote cell  1 micron (1um)  Internal structure  no internal compartments  no membrane-bound organelles  only ribosomes  circular chromosome, naked DNA  not wrapped around proteins prokaryote cell eukaryote cell

20. AP Biology 2007-2008 Eukaryotes Domain Eukarya Domain Bacteria Domain Archaea Domain Eukarya Common ancestor

21. AP Biology Eukaryote Structure  Unicellular or Multicellular  Plant, animal, fungi, protist  Size  10X larger than a prokaryote cell  10-100 micron (1um)  Internal structure  Far more complex (compartmentalized)  nucleus containing DNA  other membrane-bound organelles  ribosomes (no membrane)  Linear chromosome  wrapped around proteins prokaryote cell eukaryote cell

22. AP Biology Prokaryote vs. Eukaryote Chromosome double helix Prokaryote Eukaryote

23. AP Biology Variations in Cell Interior internal membranes for photosynthesis like a chloroplast (thylakoids) internal membranes for respiration like a mitochondrion (cristae) aerobic bacterium mitochondria cyanobacterium (photosythetic) bacterium chloroplast

24. AP Biology Prokaryote Cell Wall Structure peptide side chains cell wall peptidoglycan plasma membrane protein Gram-positive bacteria Gram-negative bacteria peptidoglycan plasma membrane outer membrane outer membrane of lipopolysaccharides cell wall peptidoglycan = polysaccharides + amino acid chains lipopolysaccharides = lipids + polysaccharides That’s important for your doctor to know!

25. AP Biology Prokaryotic metabolism  How do bacteria acquire their energy & nutrients?  photoautotrophs  photosynthetic bacteria  chemoautotrophs  oxidize inorganic compounds  nitrogen, sulfur, hydrogen…  heterotrophs  live on plant & animal matter  decomposers & pathogens

26. AP Biology Genetic variation in bacteria  Mutations  bacteria can reproduce every 20 minutes  binary fission  error rate in copying DNA  1 in every 200 bacteria has a mutation  you have billions of E. coli in your gut!  lots of mutation potential!  Genetic recombination  bacteria swap genes  plasmids  small supplemental circles of DNA  conjugation  direct transfer of DNA conjugation

27. AP Biology Bacteria as pathogens  Disease-causing microbes  plant diseases  wilts, fruit rot, blights  animal diseases  tooth decay, ulcers  anthrax, botulism  plague, leprosy, “flesh-eating” disease  STDs: gonorrhea, chlamydia  typhoid, cholera  TB, pneumonia  lyme disease

28. AP Biology Bacteria as beneficial (& necessary)  Life on Earth is dependent on bacteria  decomposers  recycling of nutrients from dead to living  nitrogen fixation  only organisms that can fix N from atmosphere  needed for synthesis of proteins & nucleic acids  plant root nodules  help in digestion (E. coli)  digest cellulose for herbivores  cellulase enzyme  produce vitamins K & B 12 for humans  produce foods & medicines  from yogurt to insulin

29. AP Biology 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.

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

31. AP Biology How big are cells?  Bacteria e.g. Eschericia coli (aka E.coli)  Size=1 µm by 3 µm

32. AP Biology How big are cells?  Human red blood cell = 8 µm in diameter

33. AP Biology How big are cells?  Largest cell on the human body = ovum  Size=  1000 µm in diameter (1 mm)

34. AP Biology How big are cells?  Smallest cell in the human body = sperm cell.

35. AP Biology How big are cells?  Largest cell with a metabolism = Chaos chaos Size=1-5 mm in length.mm common name = Giant Amoeba Chaos diffluens, is an amoeba closely related to the giant amoebaeamoebagiant

36. AP Biology How big are cells?  Largest cell = yolk of an ostrich egg

37. AP Biology Ostrich, egg, humans

38. AP Biology Ostrich emerged from egg

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

40. AP Biology Types of Microscopes 1. Compound light microscope  Light passes through lenses to magnify image up to 1000X  Can observe living cells

41. AP Biology Types of Microscopes 2. Electron microscope  Uses a beam of electrons to magnify image > 1000X  Kills cells being observed