Chapter 6: A Tour of the Cell
Concept 6.1 Biologists use microscopes and the tools of biochemistry to study cells 1. The study of cells has been limited by their small size, and so they were not seen and described until 1665, when Robert Hooke first looked at dead cells from an oak tree. His contemporary, Anton van Leeuwenhoek, crafted lenses and with the improvements in optical aids, a new world was opened. Magnification and resolving power limit what can be seen. Explain the difference. Magnification is the ratio of an object’s image size to its real size. Resolution is a measure of the clarity of the image; it is the minimum distance two points can be separated and still be distinguished as two points. 2. The development of electron microscopes has further opened our window on the cell and its organelles. What is considered a major disadvantage of electron microscopes? The methods used to prepare the specimen kill the cells. 3. Study the electron micrographs in your text. Describe the different types of images obtained from: scanning electron microscopy (SEM): Answers may vary, but should describe the 3-D component of the specimen image. transmission electron microscopy (TEM) Answers may vary, but should mention that this type of microscopy profiles a thin section of a specimen, resulting in various views of the cells prepared. 4. In cell fractionation, whole cells are broken up in a blender, and this slurry is centrifuged several times. Each time, smaller and smaller cell parts are isolated. This will isolate different organelles and allow study of their biochemical activities. Which organelles are the smallest ones isolated in this procedure? Ribosomes Concept 6.2 Eukaryotic cells have internal membranes that compartmentalize their functions 5. Which two domains consist of prokaryotic cells? Bacteria and Archaea 6. A major difference between prokaryotic and eukaryotic cells is the location of their DNA. Describe