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2: Cells and Tissues

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    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. The chapter also describes the different types of human tissue; epithelial tissue, connective tissue, muscle tissue, and nervous tissue.

    • 2.1: Cells Introduction- 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, his tiredness was going far beyond what he thought should be normal for someone who is generally in good physical shape.
    • 2.2: 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.
    • 2.3: 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.
    • 2.4: 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.
    • 2.5: 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.
    • 2.6: 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.
    • 2.7: 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.
    • 2.8: 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.
    • 2.9: Cell Reproduction- Mitosis and Meiosis
      Both mitosis and meiosis result in eukaryotic cells dividing. So what is the difference between mitosis and meiosis? The primary difference is the differing goals of each process. The goal of mitosis is to produce two daughter cells that are genetically identical to the parent cell, meaning the new cells have exactly the same DNA as the parent cell. Mitosis happens when you want to grow, for example. You want all your new cells to have the same DNA as the previous cells.
    • 2.10: Human Cells and Tissues
      This photo looks like a close-up of an old-fashioned dust mop, and the object it shows has a somewhat similar function. However, the object is greatly enlarged in the photo. Can you guess what it is? The answer may surprise you.
    • 2.11: Case Study Conclusion- Tired and Chapter Summary
      Jasmin discovered that his extreme fatigue, muscle pain, vision problems, and vomiting were due to issues in his mitochondria, an organelle. Mitochondria create energy for the cells of the body.

    2: Cells and Tissues is shared under a CK-12 license and was authored, remixed, and/or curated by LibreTexts.

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