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Unraveling Spontaneous Generation: The Historical Journey to Biogenesis in Biology

Explore the evolution of scientific thought on spontaneous generation, from Redi to Pasteur, uncovering the birth of biogenesis and the characteristics of life in biology. Understand the importance of measurements in scientific exploration with the metric system.

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Unraveling Spontaneous Generation: The Historical Journey to Biogenesis in Biology

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  1. Chapter 1 The Science of Biology

  2. What were your first questions? WHY? What? How?

  3. What is Science? Science asks the same questions you did as a young child. Science investigates and attempts to understand and explain events in nature.

  4. How do we go about doing “Science”? The Scientific Method of course!! Do some research • Propose a ___________________ • Conduct a _____________________ • Collect _____________and make observations • ______________________ data • Make a _______________________ • Possibly, write a _______________

  5. Spontaneous Generation Life arises from non-living matter or just suddenly appear. Meat grows maggots Corn produces rats Bread breeds mold So what do you think of this theory?

  6. How can we prove or disprove this hypothesis? • Francesco Redi (1668) Hypothesis: Flies produce maggots on meat. Lay small eggs Set up a controlled experiment to test his hypothesis Found that by keeping flies away from meat, no maggots appear

  7. Variables • Controlled variable: Jar, meat, location, temperature, time • Independent or Manipulative variable: Gauze covering the meat jars • Dependant (responding) variable: Whether maggots appear

  8. John Needham – 1745 Hypothesized that spontaneous generation occurs under the right conditions • Boiled chicken broth and then sealed flask (thought heat would kill) • “Animalcules” swarmed after a few days • Therefore, he felt his hypothesis was right.

  9. What was wrong with Needham’s hypothesis? Was it flawed? He assumed all the animalcules would be killed by heat

  10. LazzaroSpallanzani • 1776 • Attempted to disprove Needham’s work. • Took 4 flasks with broth in them • Left open – went cloudy • Sealed but not boiled – went cloudy • Boiled but left open – went cloudy • Sealed then boiled – stayed clear • Microbes were not found in this one but in all the other ones

  11. What would have been Spallanzani’s hypothesis?

  12. What was wrong with what Spallanzani assumed?

  13. LouisPasteur - 1859 Tested Spallanzani’s work by using a curved neck flaskto prevent microbes from entering flask but would let air in Boiled broth of control and experimental flasks. Result: No growth in curved neck flask. Microbes collecting in bend

  14. Pasteur’s broth in the curved necked flask stayed sterile for years until he tilted it and the airflow carried the microbes into the broth

  15. Conclusion Spontaneous generation theory died here!! Biogenesis is born!!

  16. What is Biology? Biology is

  17. What makes something living? Characteristics of Life All living things… • … Unicellular or Multicellular. Side 2: 531, 1562, 1610, 1619, 1627

  18. 2…haveMolecular and Cellular • Cells • Tissues • Organs • Organ systems

  19. 3…need Necessary for Metabolism - all the chemical processes taking place in the organism. Some make their own food from raw materials (Autotrophic), others need to process organic matter (heterotrophic) to obtain energy.

  20. 4…are Maintain an internal steady state – Homeostasis. Ex. Increased heart rate when stressed, goosebumps and shivering. Process leads to Evolution (a change in a species over time) 1302, 1525, 1333, 1423, 1425

  21. 5…grow 2461 Your very first baby picture Process occurs by adding on more cells by cell division (making more cells of the same kind) and cell differentiation (cells becoming different to suit their various functions). Red blood cell White blood cell Nerve cells Easily flow in vessels Change shape to Like a wire to squeeze through conduct electrical intracellular spaces impulses

  22. 6... Passing on of genetic information (DNA and genes) Not a necessary life process but needed for the continuation of the species. Sexual (involves the fusion of two cells) and Asexual (involves only 1 cell dividing) reproduction. 539, 1111 767, 761, 573 1499, 1506

  23. Measurements in Science SI Measurements (Standard Increments) aka: The Metric System Unit Abbreviation Length Meters m Mass Gram g Volume Liter l Time Second s Temperature Celsius `C Kelvin `K Density Mass/Volume g/l

  24. Symbols of measurement PrefixesAbbrevationFactor of base unit kilo k 1,000 deci d .1 or 1/10 centi c .01 or 1/100 milli m .001 or 1/1000 micro u .000001 or 1/1,000,000 nano n .000000001 or 1/1,000,000,000

  25. Metric Conversions Convert: 5L = ______ml 1.025cm = _______ m .035um = ______ mm 2.5mm = ______um 7.2g = _____kg .017g = ______mg Kilo Hecto Deka MeterDeciCenti Milli Micro Liter Gram

  26. A recipe calls for 300ml of water. You add 0.25 L. Have you put in too much, too little or the right amount? • You are told that you need a jar with a volume of at least 150cm3. The label on the jar you find says 0.16L. Can you use it? Remember that 1cm3 = 1ml.

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