PG1005 Lecture 1 The Origins of Cell Theory Dr. Neil Docherty PG1005-­‐Learning Outcomes On comple@on of the module you should be able to; 1. Recognise the main microscopic architectural features of the mammalian cell. 2.Define and explain the fundamental ac5vi5es of the mammalian cell. 3. Assign various cellular processes to a role in maintaining cellular homeostasis. 4.Assemble and describe a working model of the linkages between gene structure and protein expression in the human body. 5. Recognise and explain the role of the gene5c code in inherited traits and disease. 6. Apply knowledge of the central dogma of gene-­‐RNA–protein to the conduc@on and interpreta@on of simple laboratory classes studying gene expression and func5on at the protein level. Examina@ons 1. Con@nuous Assessment (20%) -­‐Concise essay assignment 10% due 1200 Fri 16/12/11-­‐ Physiology departmental office Topic to be announced -­‐Prac5cal class reports 5% due 1200 Mon 05/12/11-­‐Physiology departmental office 1500 words (Background,Aims,Methods,Results, Discussion & References) -­‐Prac5cal class MCQ
5% During 1500h lecture Mon 05/12/11 2. End of Year Examina@on (Trinity term) -­‐Short answer ques5ons (80%) 75% -­‐Fill-­‐in-­‐the-­‐blank/table genera5on style 10% -­‐Quan5ta5ve problem solving ques5on 15% My Teaching Objec@ves •  To introduce the cell as the basic unit of life. •  To highlight how microscopy led to the development of cell theory. •  To iden5fy those phenomena which evade defini5on by cell theory. The World Before Microscopy Some mysterious phenomena, the explana5on for which we now take for granted: • Con5nua5on of the species • Growth and Ageing • Infec5ous disease ae5ology (e.g. malaria-­‐bad air) • Non-­‐infec5ous disease mechanisms The discovery of the cell as the basic unit of life was fundamental to our understanding of all of the above and more…….. First Descrip@ons of Cells • As cells are microscopic, the microscope was fundamental. • Jan Swammerdan (1637-­‐1680) -­‐red blood cells -­‐Frog embryo (globular par5cles) • Antonio Van Leeuwenhoek (1632-­‐1723) -­‐animalcules -­‐protozoa,bacteria • Robert Hooke (1635-­‐1702) -­‐microstructure of cork -­‐Coins term “cell” for small regular units The Theory of Spontaneous Genera@on •  Circa. 343 B.C. Aristotle “Genera5on of Animals”. •  Ar5culates the theory of spontaneous genera5on prevalent for 2 millennia. •  Process driven by the elements and vital heat (pneuma). THINK OF THE APPARENT MYSTERY OF ROTTEN MEAT AND THE EMERGENCE OF MAGGOTS •  Disproving of spontaneous genera5on theory akributed to Louis Pasteur (Boiled broth experiments-­‐1859). Boiled Broth Experiments STERILE (Occasional contamina5on prevented By “ Tyndallisa5on”) CONTAMINATED Louis Pasteur 1822-­‐1895 From this discovery other breakthroughs flowed; -­‐germ theory, -­‐pasteurisa5on -­‐asep5c technique, -­‐acquired immunity, -­‐immunisa5on Cell Theory • All organisms are made up of one or more cells."
• Cells are the fundamental functional and structural unit of life."
• All cells come from pre-existing cells by division."
Origins of Cell Theory Cells cons5tute the elementary structural unit of 5ssues. 1838
Plants
Makhias Jakob Schleiden FATHERS OF CELL THEORY 1839
Animals Theodore Schwann Schleiden’s Free Cell Forma5on Theory • Theory proposed that a nucleus of “crystallisa5on” emerged in cells. • Through growth and enlargement, this body was liberated as a new cell. Rudolf Virchow (1821-­‐1902) •  Omnis cellula e cellula All cells from cells (by division) The theory followed acceptance by Virchow of the work of Robert Remak (1815-­‐1865) and Albert Kölliker (1817-­‐1905). This central dogma disproved the free cell forma@on theory. Excep@ons to Cell Theory • Viruses • Transmissible protein based infec5ous agents (prions) • Subcellular organelles which carry gene5c info and replicate independently (mitochodria/chloroplasts) • Coenocytes (mul5nucleated, single celled) e.g. Fairy rings Your Learning From Today Should focus on being able to •  Situate in your mind the cell as the basic unit of life. •  Appreciate how given the dimensions of cells, microscopy was required to inform the development of cell theory. •  Explain with reference to the rules of cell theory, how certain phenomena evade defini5on by cell theory.