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Biology LibreTexts

1: Cell Tour, Life’s Properties and Evolution, Studying Cells

  • Page ID
    16414
    • 1.1: Introduction
      "... Many of these studies revealed common structural features including a nucleus, a boundary wall and a common organization of cells into groups to form multicellular structures of plants and animals and even lower life forms. These studies led to the first two precepts of Cell Theory"
    • 1.2: Scientific Method – The Practice of Science
      Long before the word scientist began to define someone who investigated natural phenomena beyond simple observation (i.e., by doing experiments), philosophers developed formal rules of deductive and inferential logic to try to understand nature, humanity’s relationship to nature, and the relationship of humans to each other.
    • 1.3: Domains of Life
      The three domains of life (Archaea, Eubacteria and Eukarya) quickly supplanted the older division of living things into Five Kingdoms, the Monera (prokaryotes), Protista, Fungi, Plants, and Animals (all eukaryotes!). In a final surprise, the sequences of archaebacterial genes clearly indicate a common ancestry of archaea and eukarya.
    • 1.4: Tour of the Eukaryotic Cell
      An exploration of the organelles that makeup a eukaryotic cell.
    • 1.5: How We Know the Functions of Cellular Organelles and Structures: Cell Fractionation
      We can see and describe cell parts in the light or electron microscope, but we could not definitively know their function until it became possible to release them from cells and separate them from one another. This became possible with the advent of differential centrifugation. Under centrifugal force generated by a spinning centrifuge, subcellular structures separate by differences in mass. Structures that are more massive reach the bottom of the centrifuge tube before less massive ones.
    • 1.6: The Origins, Evolution, Speciation, Diversity and Unity of Life
      The question of how life began has been with us since the beginnings or recorded history. It is now accepted that there was a time, however brief or long, when the earth was a lifeless (prebiotic) planet. Life’s origins on earth date to some 3.7-4.1 billion years ago under conditions that favored the formation of the first cell, the first entity with all of the properties of life.
    • 1.7: Microscopy Reveals Life’s Diversity of Structure and Form
      Broadly speaking, there are two kinds of microscopy. In Light Microscopy, the specimen on the slide is viewed through optical glass lenses. In Electron Microscopy, the viewer is looking at an image on a screen created by electrons passing through, or reflected from the specimen. For a sampling of light and electron micrographs, check out this Gallery of Micrographs. Here we compare and contrast different microscopic techniques.
    • 1.8: Key Words and Terms