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Biology LibreTexts

5: Cells

  • Page ID
    16745
  • This chapter outlines the discovery of cells and cell theory. It identifies ways in which all cells are alike and ways in which they vary. The chapter describes in detail important cell structures and their functions; and it explains how cells obtain energy, grow, and divide.

    • 5.1: Case Study - The Importance of Cells
      We all get tired sometimes, especially if we have been doing a lot of physical activity like these hikers. But for Jasmin, a 34 year old former high school track star who is now a recreational runner, her tiredness was going far beyond what she thought should be normal for someone who is generally in good physical shape.
    • 5.2: Discovery of Cells and Cell Theory
      Cells are the basic units of the structure and function of living things. All organisms are made up of one or more cells, and all cells have many of the same structures and carry out the same basic life processes.
    • 5.3: Variation in Cells
      Although all living cells have certain things in common, different types of cells, even within the same organism, may have their unique structures and functions. Cells with different functions generally have different shapes that suit them for their particular job.
    • 5.4: Plasma Membrane
      The plasma membrane is a structure that forms a barrier between the cytoplasm inside the cell and the environment outside the cell. The membrane protects and supports the cell and controls everything that enters and leaves it.
    • 5.5: Cytoplasm and Cytoskeleton
      The cytoplasm is a thick, usually colorless solution that fills each cell and is enclosed by the cell membrane. Sometimes cytoplasm acts like a watery solution, and sometimes it takes on a more gel-like consistency. A framework of protein scaffolds called the cytoskeleton provides the cytoplasm and the cell with structure.
    • 5.6: Cell Organelles
      An organelle is a structure within the cytoplasm of a eukaryotic cell that is enclosed within a membrane and performs a specific job. Organelles in animal cells include the nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, vesicles, and vacuoles.
    • 5.7: Cell Transport
      If a cell were a house, the plasma membrane would be walls with windows and doors. Moving things in and out of the cell is an important role of the plasma membrane. It controls everything that enters and leaves the cell. There are two basic ways that substances can cross the plasma membrane: passive transport, which requires no energy; and active transport, which requires energy.
    • 5.8: Active Transport and Homeostasis
      When substances require energy to cross a plasma membrane often because they are moving from an area of a lower concentration to an area of a higher concentration, the process is called active transport.
    • 5.9: Cellular Respiration
      Energy is required to break down and build up molecules and to transport many molecules across plasma membranes. A lot of energy is lost to the environment as heat. The story of life is a story of energy flow - its capture, its change of form, its use for work, and its loss as heat.
    • 5.10: Anaerobic Respiration
      The cells of living things power their activities with the energy-carrying molecule ATP. The cells of most living things make ATP from glucose in the process of cellular respiration. This process occurs in three stages: glycolysis, the Krebs cycle, and electron transport.
    • 5.11: Case Study Tired Conclusion and Chapter Summary
      Jasmin discovered that her extreme fatigue, muscle pain, vision problems, and vomiting were due to issues in her mitochondria, an organelle. Mitochondria create energy for the cells of the body.