CHAPTER 7: THE BASIS OF LIFE Unit C: Biology – Science 10

Section 7.1 – Life From Life Chapter 7

Introduction to Cells

Characteristics All living things share 5 characteristics: Need energy Produce wastes Respond and adapt to their environment Reproduce Grow

Bill Nye Spontaneous Generation https://www.youtube.com/watch?v=Dlbh6024R1c TED Talk and Cell Theory https://www.youtube.com/watch?v=4OpBylwH9DU

Where does life come from? Aristotle Observed that some organisms reproduce asexually and others sexually Couldn’t observe any reproductive processes in small organisms He thought that some life forms could arise from non- living matter (spontaneous generation or abiogenesis)

Francesco Redi (1626-1697) First person to test the theory of spontaneous generation Did not believe that maggots arose from rotting meat Hypothesized that the maggots hatched from eggs dropped from flies that landed on the meat

Redi’s Experiment Placed meat into two glass jars Covered one jar with a cloth that let air in and out but kept out flies and left the other jar open A few days later he observed that there were maggots in the open jar but not in the covered jar Was the first to give evidentiary support that spontaneous generation did not occur Figure 7.2, page 259

Louis Pasteur (1822-1895) Believed in biogenesis – life comes from life Designed a glass flask with a S-shaped neck Put a nutrient rich broth inside and boiled it to kill any microbes Let sit for several days and noticed that the broth remained clear indicating that no micro-organisms entered the flask

Cell Theory Robert Hooke (1635-1703) Looked at thin slices of cork from the bark of a tree under a compound light microscope Observed many little “rooms” He named the structures cells because they looked like monk’s small rooms in a monastery

Antony van Leeuwenhoek (1632-1723) First person to describe single-celled micro-organisms Studied blood cells, pond-water organisms, matter scraped from his teeth Made microscopes much more powerful than those Hooke used

Matthias Jakob Schleiden (1804-1881) and Theodor Schwann (1810-1882) Compared their findings and came to the same conclusion that ALL organisms contain cells observed nuclei in all cells and concluded that each new cell came from the nucleus

Cell Theory All organisms are composed of one or more cells. The cell is the smallest functional unit of life. All cells are produced from other cells.