THE CELLTHEORY
What level of complexity is  necessary for life?      Aristotle (384 – 322BC)                            Unorganised     ...
Tissues and OrgansImage Credit                    Image Credit Kidney longitudinal sectionMuscle tissue (surloin steak)
What level of complexity is  necessary for life?  C17th microscopists discovered tissues  were made of cells (Hooke 1665 a...
CellsC18th and C19thshowed thattissues weremade of cellsThe cells of aparticular tissuehad a commonstructure.          Ima...
What is a cell?   Taken to its simplest form   A plasma membrane…   Surrounding cytoplasm…   Containing hereditary mat...
What level of complexity is  necessary for life?      Xavier Bichat               Organism       (1771-1802): An organ   ...
What level of complexity is  necessary for life?   Purkinje (1835) Observed a fertilised hens    egg (a single cell) coul...
THE CELL THEORY   Matthias Schleiden (1838) & Theodor    Schwann (1839)    “The cell is the basic unit of living    tissu...
« Omnis cellula e cellula »Rudolf Virchow (1858)noted that:“all cells come frompre-existing cells”                        ...
THE ORGANISMAL THEORYThe counter arguments:Reichert a morphologist: Argued that anorganism has a structured planImage Cred...
PlasmodesmataStrasberger acytologist: Cells areconnected in anorganism sometimes bycytoplasmic bridges                    ...
Acellular organismsSome organisms donot have cellularcompartments                    Image Credit Common field mushroom (A...
HomeostasisSherrington andPavlovneurophysiologists:Cells communicatewith one another andthey are co-ordinatedin their acti...
Unicellular organisms Some organisms only consist of a single  cell But these do usually have the components  of cells (...
Cellular components Some cells lack the basic components But as a result their functions are affected.                  ...
Tissue culture Cells can be cultured away from a body But this often requires elaborate support  systems                ...
SUMMARY       THE CELL THEORY                          THE ORGANISMAL                                                    T...
SUMMARY       THE CELL THEORY                       THE ORGANISMAL                                                 THEORY3...
Cell theory or organismal  theory?   That the cell is the basic unit of living    organisms is accepted   That unicellul...
More is different!   As a multicellular organism grows and    develops it follows a structured plan   The cells speciali...
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Ch.1 the cell (theory)

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Ch.1 the cell (theory)

  1. 1. THE CELLTHEORY
  2. 2. What level of complexity is necessary for life?  Aristotle (384 – 322BC) Unorganised material (non-living) Homogeneous Matter (tissues) Organised material (living) Heterogeneous (organs)© 2010 Paul Billiet ODWS
  3. 3. Tissues and OrgansImage Credit Image Credit Kidney longitudinal sectionMuscle tissue (surloin steak)
  4. 4. What level of complexity is necessary for life? C17th microscopists discovered tissues were made of cells (Hooke 1665 and Leeuwenhoek 1677) Image Credit Cork cells© 2010 Paul Billiet ODWS
  5. 5. CellsC18th and C19thshowed thattissues weremade of cellsThe cells of aparticular tissuehad a commonstructure. Image Credit Liver cells
  6. 6. What is a cell?  Taken to its simplest form  A plasma membrane…  Surrounding cytoplasm…  Containing hereditary material.© 2010 Paul Billiet ODWS
  7. 7. What level of complexity is necessary for life?  Xavier Bichat Organism (1771-1802): An organ is composed of different Organ-system tissues  Several organs can be Organ grouped together as an organ system (e.g. the Tissue digestive system)  An idea of hierarchy of Cell structure developed:© 2010 Paul Billiet ODWS
  8. 8. What level of complexity is necessary for life?  Purkinje (1835) Observed a fertilised hens egg (a single cell) could develop into an embryo (many specialised cells in a compact mass)  C19th botanists showed that plant tissues consist of many different types of cells.© 2010 Paul Billiet ODWS
  9. 9. THE CELL THEORY  Matthias Schleiden (1838) & Theodor Schwann (1839) “The cell is the basic unit of living tissue”  The cell is an autonomous unit (“a citizen”) grouped together to form an organism (“the society”).© 2010 Paul Billiet ODWS
  10. 10. « Omnis cellula e cellula »Rudolf Virchow (1858)noted that:“all cells come frompre-existing cells” Image Credit Cell division
  11. 11. THE ORGANISMAL THEORYThe counter arguments:Reichert a morphologist: Argued that anorganism has a structured planImage Credit Frog embryo Image Credit Frog embryo fate map
  12. 12. PlasmodesmataStrasberger acytologist: Cells areconnected in anorganism sometimes bycytoplasmic bridges Image Credit Black sapote (Diospyros) fruit
  13. 13. Acellular organismsSome organisms donot have cellularcompartments Image Credit Common field mushroom (Agaricus bisporus) Image Credit Fungal hyphae
  14. 14. HomeostasisSherrington andPavlovneurophysiologists:Cells communicatewith one another andthey are co-ordinatedin their actions Image Credit Spiney dendrites of the hippocampus region of the brai
  15. 15. Unicellular organisms Some organisms only consist of a single cell But these do usually have the components of cells (nucleus, membrane etc) Image Credit Paramecium
  16. 16. Cellular components Some cells lack the basic components But as a result their functions are affected. Image Credit Red blood cells
  17. 17. Tissue culture Cells can be cultured away from a body But this often requires elaborate support systems Image Credit Tissue culture hood U of Wisconsin
  18. 18. SUMMARY THE CELL THEORY THE ORGANISMAL THEORY1. Multicellular organisms develop  1. Some organisms are not divided from a single fertilised germ cell (the  into cellular compartments zygote) = non-cellular2. The basic components of the cell  2. Certain cells lack the basic are repeated in every cell components Cells in multicellular organisms are  highly specialised Unicellular organisms have a  cytoplasm that is not subdivided  Should be considered as acellular© 2010 Paul Billiet ODWS
  19. 19. SUMMARY THE CELL THEORY THE ORGANISMAL THEORY3. All cells come from cells 3. Remove cells from complete  multicellular organisms requires Cells can be taken from organisms  elaborate life support systems to keep and cultured away from the body them aliveNew individuals can be cultured from isolated cells Regeneration capacity = totipotence 4. Homeostatic control and co- ordination is required to maintain the  whole organism whether it is  unicellular or multicellular.© 2010 Paul Billiet ODWS
  20. 20. Cell theory or organismal theory?  That the cell is the basic unit of living organisms is accepted  That unicellular organisms carry out all the functions of life is accepted  BUT multicellular organisms are not simply a mass of similar building blocks© 2010 Paul Billiet ODWS
  21. 21. More is different!  As a multicellular organism grows and develops it follows a structured plan  The cells specialise (differentiate)  The whole organism shows homeostatic control  A developing multicellular organism shows emergent properties  It is not just the sum of the parts© 2010 Paul Billiet ODWS

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