1: Cell Tour, Life’s Properties and Evolution, Studying Cells
Learning Objectives
When you have mastered the information in this chapter, you should be able to:
- compare and contrast hypotheses and theories and place them and other elements of the scientific enterprise into their place in the cycle of the scientific method.
- compare and contrast structures common to and that distinguish prokaryotes , eukaryotes and archaea , and groups within these domains.
- articulate the function of different cellular substructures.
- explain how prokaryotes and eukaryotes accomplish the same functions, i.e. have the same properties of life , even though prokaryotes lack most of the structures.
- outline a procedure to study a specific cell organelle or other substructure.
- describe how the different structures (particularly in eukaryotic cells) relate/interact with each other to accomplish specific functions.
- describe some structural and functional features that distinguish prokaryotes (eubacteria), eukaryotes and archaea.
- place cellular organelles and other substructures in their evolutionary context, i.e., describe their origins and the selective pressures that led to their evolution.
- distinguish between the random nature of mutation and natural selection in evolution
- relate archaea to other life forms and speculate on their origins in evolution.
- suggest why evolution leads to more complex ways of sustaining life,
- explain how fungi are more like animals than plants.
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- 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"
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- 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.
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- 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.
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- 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.
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- 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.
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- 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.
Thumbnail: Life cycle of the cell. (CC BY-SA 4.0; BruceBlaus).