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Lecture Biology (6e): Chapter 7 - Campbell, Reece

Chapter 7 - A tour of the cell. This chapter distinguish between the following pairs of terms: magnification and resolution, prokaryotic and eukaryotic cell, free and bound ribosomes, smooth and rough ER; describe the structure and function of the components of the endomembrane system; briefly explain the role of mitochondria, chloroplasts, and peroxisomes. | CHAPTER 7 A TOUR OF THE CELL Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Section A: How We Study Cells 1. Microscopes provide windows to the world of the cell 2. Cell biologists can isolate organelles to study their function The discovery and early study of cells progressed with the invention and improvement of microscopes in the 17th century. In a light microscope (LM) visible light passes through the specimen and then through glass lenses. The lenses refract light such that the image is magnified into the eye or onto a video screen. 1. Microscopes provide windows to the world of the cell Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Microscopes vary in magnification and resolving power. Magnification is the ratio of an object’s image to its real size. Resolving power is a measure of image clarity. It is the minimum distance two points can be separated by and still be viewed as two separate points. Resolution is limited by the shortest wavelength of the source, in this case light. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings The minimum resolution of a light microscope is about 2 microns, the size of a small bacterium Light microscopes can magnify effectively to about 1,000 times the size of the actual specimen. At higher magnifications, the image blurs. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 7.1 Techniques developed in the 20th century have enhanced contrast and enabled particular cell components to be labeled so that they stand out. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings While a light microscope can resolve individual cells, it cannot resolve much of the internal anatomy, especially the organelles. To resolve smaller structures we use an electron microscope (EM), which focuses a beam of electrons through the specimen or onto its surface. Because resolution is inversely related to wavelength used, . | CHAPTER 7 A TOUR OF THE CELL Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Section A: How We Study Cells 1. Microscopes provide windows to the world of the cell 2. Cell biologists can isolate organelles to study their function The discovery and early study of cells progressed with the invention and improvement of microscopes in the 17th century. In a light microscope (LM) visible light passes through the specimen and then through glass lenses. The lenses refract light such that the image is magnified into the eye or onto a video screen. 1. Microscopes provide windows to the world of the cell Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Microscopes vary in magnification and resolving power. Magnification is the ratio of an object’s image to its real size. Resolving power is a measure of image clarity. It is the minimum distance two points can be separated by and still be viewed as two separate points. Resolution is limited by the