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Unit 1: Chapter 1 Matter and Energy For Life

Unit 1: Chapter 1 Matter and Energy For Life. Development of the Cell Theory. For hundreds of years a debate raged amongst scientists, about the origin of living things. The debate centered around two theories: Abiogenesis Biogenesis. Onion skin cells. Paramecium. What is abiogenesis?.

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Unit 1: Chapter 1 Matter and Energy For Life

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  1. Unit 1: Chapter 1Matter and Energy For Life

  2. Development of the Cell Theory • For hundreds of years a debate raged amongst scientists, about the origin of living things. • The debate centered around two theories: • Abiogenesis • Biogenesis Onion skin cells Paramecium

  3. What is abiogenesis? • Abiogenesis is the idea that living organisms can arise from non-living matter. • It is also called Spontaneous Generation • Thomas Huxley first used the term abiogenesis

  4. Examples of abiogenesis: • Appearances of mushrooms on logs • Maggots forming on rotting meat • Frogs and salamanders suddenly appearing on or in mud

  5. What scientists supported abiogenesis? • Aristotle (384-322 B.C.E.) classifies all organisms into 2 kingdoms: plants and animals. • He believed all living organisms can only arise from non-living matter.

  6. John Needham (1713-1781) • He believed microorganisms appeared in a sterilized flask of meat broth

  7. He placed broth into a bottle, heated the bottle to kill anything inside, then sealed it. • Days later, he reported the presence of life in the broth and announced that life had been created from nonlife. • What actually happened? • He did not heat the broth long enough to kill all the microbes. Therefore, after a few days, microbes (ex: mold) appeared in the bottle.

  8. Biogenesis is the idea that living organisms can only come from other living things. What is biogenesis?

  9. What scientists supported biogenesis? Francesco Redi (1629-1697) • He made the first serious attack on abiogenesis. During this time, people believed maggots just appeared on rotting meat. • Redi believed that maggots actually came from fly eggs, which are not visible to the eye. He performed an experiment to show that maggots will not appear on rotting meat if flies are kept away.

  10. Francesco Redi’s Experiment • See page 8 in textbook http://www.sumanasinc.com/webcontent/animations/content/scientificmethod.html

  11. Spallanzani (1729-1799) • He was skeptical of Needham’s experiment, so he did his own • He boiled the broth for a longer period of time and he kept one of the bottles sealed. • No life appeared in the sealed bottle

  12. Louis Pasteur (1822-1895) • He ended the debate on abiogenesis • He designed an experiment to prove microbes do not just appear in sterilized meat broth. • Instead, these microbes actually come from the air. http://bcs.whfreeman.com/thelifewire/content/chp03/0302003.html

  13. http://www.sumanasinc.com/webcontent/animations/content/scientificmethod.htmlhttp://www.sumanasinc.com/webcontent/animations/content/scientificmethod.html

  14. Paradigm Shift • As a result of the debate over abiogenesis and biogenesis there was a change in the way that science viewed the “origins of life”. • The cell theory was developed Cell Theory Video http://www.youtube.com/watch?v=dscY_2QQbKU

  15. Other Scientists that contributed to the development of the cell theory: • Robert Hooke (1665) using a primitive set of lenses to form a simple microscope, observes “empty room like apartments” in samples of once living tree bark. Hooke names these compartments cells.

  16. Anton van Leeuwenhoek (1667) designs his own microscopes that are far more powerful than any of the primitive forms at the time. Over the next number of years Leeuwenhoek writes extensively about his observations of tiny living organisms.

  17. Robert Brown (1831)observes a darker region in all cells near the centre and named it the nucleus.

  18. Mathias Jacob Schleiden (1838) writes, “All plants are made of cells”.

  19. Theodor Schwann (1839) writes “All animals are made up of cells” and further goes on to state that “Cells are organisms and entire animals and plants are collectives of these organisms”.

  20. Alexander Carl Henrich Braun (1845) wrote “the cell is the basic unit of life”.

  21. Rudolph Virchow (1858) formulates the points of the cell theory.

  22. The wacky history of cell theory – by Lauren Royal-Woods http://ed.ted.com/lessons/the-wacky-history-of-cell-theory

  23. (*Important: please write!)Cell Theory • All living organisms are composed of one or more cells • Cells are the basic units of structure and function in all organisms • All cells are derived (come from) pre-existing cells (biogenesis) • In a multicellular organism, the activity of the entire organism depends on the total activity of its independent cells.

  24. The cell theory song • http://www.youtube.com/watch?v=KuJqqiATlqw

  25. Work: • Review worksheet/handout on Scientists • In class assignment on Scientists

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