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In this chapter, we will address the following questions: What features of cells make them the fundamental unit of life? what are the characteristics of prokaryotic cells? What are the characteristics of eukaryotic cells? What are the roles of extracellular structures? How did eukaryotic cells originate? | Cells: The Working Units of Life 4 Cells: The Working Units of Life 4.1 What Features of Cells Make Them the Fundamental Unit of Life? 4.2 What Are the Characteristics of Prokaryotic Cells? 4.3 What Are the Characteristics of Eukaryotic Cells? 4.4 What Are the Roles of Extracellular Structures? 4.5 How Did Eukaryotic Cells Originate? 4.1 What Features of Cells Make Them the Fundamental Unit of Life? Cell theory was the first unifying theory of biology. Cells are the fundamental units of life. All organisms are composed of cells. All cells come from preexisting cells. 4.1 What Features of Cells Make Them the Fundamental Unit of Life? Implications of cell theory: Functions of all cells are similar Life is continuous Origin of life was the origin of cells 4.1 What Features of Cells Make Them the Fundamental Unit of Life? Cells are small (mostly). Exceptions: bird eggs, neurons, some algae and bacteria cells Figure 4.1 The Scale of Life (Part 1) Figure 4.1 The Scale of Life (Part 2) 4.1 What Features of Cells Make Them the Fundamental Unit of Life? Cells are small because they need a high surface area-to-volume ratio. Volume determines the amount of chemical activity in the cell per unit time. Surface area determines the amount of substances that can pass the cell boundary per unit time. Figure 4.2 Why Cells Are Small (Part 1) Figure 4.2 Why Cells Are Small (Part 2) 4.1 What Features of Cells Make Them the Fundamental Unit of Life? Most cells are < 200 μm in size. Minimum resolution of human eye is 200 μm. Microscopes improve resolution. 4.1 What Features of Cells Make Them the Fundamental Unit of Life? Two basic types of microscope: Light microscope—uses glass lenses and light. Resolution = 0.2 μm Electron microscope—electromagnets focus an electron beam. Resolution = 0.2 nm Figure 4.3 Looking at Cells (Part 1) Figure 4.3 Looking at Cells (Part 2) Figure 4.3 Looking at Cells (Part 3) 4.1 What Features of Cells Make Them the Fundamental Unit of Life? All cells are . | Cells: The Working Units of Life 4 Cells: The Working Units of Life 4.1 What Features of Cells Make Them the Fundamental Unit of Life? 4.2 What Are the Characteristics of Prokaryotic Cells? 4.3 What Are the Characteristics of Eukaryotic Cells? 4.4 What Are the Roles of Extracellular Structures? 4.5 How Did Eukaryotic Cells Originate? 4.1 What Features of Cells Make Them the Fundamental Unit of Life? Cell theory was the first unifying theory of biology. Cells are the fundamental units of life. All organisms are composed of cells. All cells come from preexisting cells. 4.1 What Features of Cells Make Them the Fundamental Unit of Life? Implications of cell theory: Functions of all cells are similar Life is continuous Origin of life was the origin of cells 4.1 What Features of Cells Make Them the Fundamental Unit of Life? Cells are small (mostly). Exceptions: bird eggs, neurons, some algae and bacteria cells Figure 4.1 The Scale of Life (Part 1) Figure 4.1 The Scale of Life (Part 2) 4.1
