1. A Tour of the Cell, Part I CHAPTER 4  Microscopes as Windows on Cells o Types of Microscopes o Magnification and Resolution  Categories of Cells  Features of Prokaryotic Cells  Features of Eukaryotic Cells o Membrane Structure o Nucleus and Ribosomes o Endoplasmic Reticulum (ER)

2. Cells Are Small (1-100  m)

3. Magnification and Resolution in Microscopy Magnification is the ability of a microscope to enlarge an image. -Magnification is almost unlimited on a microscope. Resolution is the ability of a microscope to clearly define the details of what it is looking at. - Microscopes that use lower wavelengths of electromagnetic energy, like electron microscopes, have better resolution of tiny details and can be used at higher magnifications (100,000X). -Resolution limits the usefulness of high magnification since once an object becomes blurry; greater magnification doesn't help. Light microscopes are limited to 1000X.

4. The Microscopic World of Cells Cells were first discovered in 1665 by Robert Hooke. The accumulation of scientific evidence led to the cell theory which has two main tenets: 1.All living things are composed of cells. 2.All cells are formed from previously existing cells. Organisms are either: –Single-celled, such as most bacteria and protists –Multicellular, such as plants, animals, and most fungi

5. Types of Microscopes Light Microscopes use visible light and optical lenses –Limited to 1000X because of low resolution –Require little or no electrical power to operate Euglena

6. Electron microscopes (EMs) use a beam of electrons and magnetic lenses –Much higher resolving power than the light microscope and can magnify up to 100,000X. Types of Microscopes –Types of Electron Microscopes The scanning electron microscope (SEM) is used to study the detailed architecture of the surface of a cell. The transmission electron microscope (TEM) is useful for exploring the internal structure of a cell.

7. A Tour of the Cell, Part I CHAPTER 4  Microscopes as Windows on Cells o Types of Microscopes o Magnification and Resolution  Categories of Cells  Features of Prokaryotic Cells  Features of Eukaryotic Cells o Membrane Structure o Nucleus and Ribosomes o Endoplasmic Reticulum (ER)

8. The Two Major Categories of Cells The countless cells on earth fall into two categories: –Prokaryotic cells, such as bacteria –Eukaryotic cells, such as protist, fungal, plant, or animal cells

9. Comparison of Prokaryotic and Eukaryotic Cells

10. A Tour of the Cell, Part I CHAPTER 4  Microscopes as Windows on Cells o Types of Microscopes o Magnification and Resolution  Categories of Cells  Features of Prokaryotic Cells  Features of Eukaryotic Cells o Membrane Structure o Nucleus and Ribosomes o Endoplasmic Reticulum (ER)

11. Prokaryotic Cells Are Small and Simple

12. A Tour of the Cell, Part I CHAPTER 4  Microscopes as Windows on Cells o Types of Microscopes o Magnification and Resolution  Categories of Cells  Features of Prokaryotic Cells  Features of Eukaryotic Cells o Membrane Structure o Nucleus and Ribosomes o Endoplasmic Reticulum (ER)

13. Eukaryotic Cells are Larger and More Complex

15. A Tour of the Cell, Part I CHAPTER 4  Microscopes as Windows on Cells o Types of Microscopes o Magnification and Resolution  Categories of Cells  Features of Prokaryotic Cells  Features of Eukaryotic Cells o Membrane Structure o Nucleus and Ribosomes o Endoplasmic Reticulum (ER)

16. Membrane Structure The plasma membrane separates the living cell from its nonliving surroundings Phospholipids form an impermeable bilayer Proteins provide transport channels and other functions

17. Plant cells have rigid cell walls of cellulose –Provide protection, maintain cell shape, and keep cells from absorbing too much water. Animal cells have an extracellular matrix –Holds cells together in tissues and protects and supports them. Structures Found Outside the Cell Membrane in Eukaryotes

18. A Tour of the Cell, Part I CHAPTER 4  Microscopes as Windows on Cells o Types of Microscopes o Magnification and Resolution  Categories of Cells  Features of Prokaryotic Cells  Features of Eukaryotic Cells o Membrane Structure o Nucleus and Ribosomes o Endoplasmic Reticulum (ER)

19. Organelles Within A Eukaryotic Cell

20. The Nucleus: Information Storage and Control of the Cell The nucleus is the library of the cell. Chromosomes (books) within the nucleus store instructions on how to run the cell

21. Ribosomes Make Proteins Using Genetic Instructions Copy of instructions from the nucleus

22. A Tour of the Cell, Part I CHAPTER 4  Microscopes as Windows on Cells o Types of Microscopes o Magnification and Resolution  Categories of Cells  Features of Prokaryotic Cells  Features of Eukaryotic Cells o Membrane Structure o Nucleus and Ribosomes o Endoplasmic Reticulum (ER)

23. The Endomembrane System: Manufacturing and Distributing Cellular Products Many of the membranous organelles in the cell belong to the endomembrane system.

24. The Endoplasmic Reticulum The endoplasmic reticulum (ER) –Lipid synthesis factory, including phospholipids for cell membrane –Routing system for delivery of proteins (subway system)

25. A Tour of the Cell, Part I CHAPTER 4  Microscopes as Windows on Cells o Types of Microscopes o Magnification and Resolution  Categories of Cells  Features of Prokaryotic Cells  Features of Eukaryotic Cells o Membrane Structure o Nucleus and Ribosomes o Endoplasmic Reticulum (ER)