Cell Structure and Function Science Chapter 12 Science

Cell Structure and Function Science: Chapter 12

Science: Chapter 12 Cell Structure and Function 12. 1 Discovering Cells

Cell Structure and Function 12. 1 Discovering Cells An Overview of Cells �What are cells? �How did the invention of the microscope contribute to knowledge about living things? �What is the cell theory? �How do microscopes produce magnified images?

Cell Structure and Function 12. 1 Discovering Cells Key Terms �cell �microscope �cell theory

Cell Structure and Function 12. 1 Discovering Cells �Cells are the basic unit of structure and function in living things. Cells and Structure When you describe the structure of an object, you describe what it is made of and how its parts are put together. Cells and Function An organism’s functions are processes that enable it to stay alive and reproduce.

Cell Structure and Function 12. 1 Discovering Cells Many and Small No matter how closely you look with your eyes alone, you won’t be able to see individual cells. Until the late 1600 s’ no one knew cells existed because there was no way to see them.

Cell Structure and Function 12. 1 Discovering Cells First Observations of Cells �The invention of the microscope made it possible for people to discover and learn about cells. �A microscope is an instrument that makes small objects look larger.

Cell Structure and Function 12. 1 Discovering Cells �Some microscopes make objects look larger by using lens to focus light. �Lens used in light microscopes are similar to clear, curved pieces of glass or plastic used in eyeglasses. �A simple microscope contains only one lens. �A light microscope that has more than one lens is called a compound microscope.

Cell Structure and Function 12. 1 Discovering Cells � 1590 -First compound microscope was made by Dutch eyeglass makers Zacharias and Hans Janssen.

Cell Structure and Function 12. 1 Discovering Cells � 1660 Hooke’s Compound Microscope-Robert Hooke’s compound microscope included an oil lamp for lighting. A lens focused light from the flame onto the specimen.

Cell Structure and Function 12. 1 Discovering Cells Hooke’s Compound Microscope Diagram of Hooke’s Compound Microscope

Cell Structure and Function 12. 1 Discovering Cells � 1674 Leeuwenhoek’s Simple Microscope. Although Anton van Leuwenhoek’s simple microscope used only one tiny lens, it could magnify a specimen up to 266 times.

Cell Structure and Function 12. 1 Discovering Cells Anton van Leuwenhoek’s simple microscope Diagram of Anton van Leuwenhoek’s simple microscope

Cell Structure and Function 12. 1 Discovering Cells � 1886 Modern Compound Light Microscope-German scientists Ernst Abbe and Carl Zeiss made a compound microscope with complex lenses that greatly improved the image. A mirror focuses light up through the specimen. Modern compound microscopes can effectively magnify a specimen up to 1, 000 times. Ernest Abbe Carl Zeiss

Cell Structure and Function 12. 1 Discovering Cells 1886 MODERN COMPOUND MICROSCOPE THE COMPOUND MICROSCOPE TODAY

Cell Structure and Function 12. 1 Discovering Cells � You will have to be able to identify the parts of the compound light microscope.

Cell Structure and Function 12. 1 Discovering Cells �Other types of microscopes Ø 1933 -Transmission Electronic Microscope (TEM) Ø 1965 -Scanning Electron Microscope (SEM) Ø 1981 -Scanning Tunneling Microscope (STM) (TEM) (STM)

Cell Structure and Function 12. 1 Discovering Cells Transmission Electron Microscope (TEM)-German physicist Ernst Ruska created the first electron microscope. TEMs send electrons through a very thinly sliced specimen. TEMs can magnify a specimen up to 500, 000 times. Ernst Ruska � 1933 TEM

Cell Structure and Function 12. 1 Discovering Cells � 1965 Scanning Electron Microscope (SEM)-An SEM sends electrons over the surface of a specimen, rather than through it. The result is a threedimensional image of the specimen’s surface. SEMs can magnify a (TEM) specimen up to 150, 000 times.

Cell Structure and Function 12. 1 Discovering Cells � 1981 Scanning Tunneling Microscope (STM)An STM measures electrons that leak, or “tunnel, ” from the surface of a specimen. STMs can magnify a specimen up to 1, 000 times.

Cell Structure and Function 12. 1 Discovering Cells Development of Cell Theory �The discoveries made with the use of the microsope lead to further curiosity about cells. �Three German scientist made especially important contributions to people’s knowledge about cells.

Cell Structure and Function 12. 1 Discovering Cells Matthias Schleiden Theodor Schwann Rudolf Virchow

Cell Structure and Function 12. 1 Discovering Cells � In 1838, Schleiden concluded that all plants are made of cells. He based this conclusion on his own research and the research of others.

Cell Structure and Function 12. 1 Discovering Cells � The next year, Schwann concluded that all animals are also made up of cells. Thus, stated Schwann, all things are made up of living cells.

Cell Structure and Function 12. 1 Discovering Cells �Schleiden and Schwann had made an important discovery about living things. However, they didn’t explain where cells came from. �Before then, people thought that living things could come from nonliving matter.

Cell Structure and Function 12. 1 Discovering Cells � In 1955, Virchow proposed that new cells are formed only from cells that already exist. “All cells come from cells, ” wrote Virchow.

Cell Structure and Function 12. 1 Discovering Cells Cell Theory The cell theory states the following: �All living things are composed of cells. �Cells are the basic units of structure and function in living things. �All cells are produced from other cells.

Cell Structure and Function 12. 1 Discovering Cells �The cell theory could not have been developed without the invention of the microscope. �For a microscope to be useful, it must combine two important properties. Magnification and light �Today we use two kinds of microscopes: light microscopes and electron microscopes.

Cell Structure and Function 12. 1 Discovering Cells Construct a flowchart showing how the work of Hooke, Leeuwenhoek, Schleiden, Schwann, and Virchow contributed to scientific understanding of cells. Sequencing �Hooke sees cells in �Leeuwenhoek sees cork. many one-celled organisms. �Schleiden concludes that all plants are made of cells. �Schwann concludes that all animals (and all living things) are made of cells. �Virchow proposes that new cells form only from cells that already exist.

Cell Structure and Function 12. 1 Discovering Cells Magnification and Lenses � Magnification-the ability to make things look larger than they are. � The lens in light microscopes magnify an object by bending the light that passes through them.

Cell Structure and Function 12. 1 Discovering Cells �Since Compound Microscope Magnification a compound microscope uses more than one lens, it can magnify an object more than one lens by itself. �Light passes through a specimen and then through two lenses. �The first lens, near the specimen, magnifies the object. �The second lens, near the eye, further magnifies the enlarged image.

Cell Structure and Function 12. 1 Discovering Cells Compound Microscope Magnification Since a compound microscope uses more than one lens, it can magnify an object more than one lens by itself. � Light passes through a specimen and then through two lenses. � The first lens, near the specimen, magnifies the object. � The second lens, near the eye, further magnifies the enlarged image. �

Cell Structure and Function 12. 1 Discovering Cells �The ability to clearly distinguish the individual parts of an object is called resolution. �Resolution is another term for sharpness of an image.

Cell Structure and Function 12. 1 Discovering Cells �Electron Microscopes use a beam of electrons instead of light to produce a magnified image. �Electron microscopes can obtain pictures of extremely small objects-much smaller than those that can be seen with light microscopes. �The resolution of electron microscopes is much better than the resolution of light microscopes.

Cell Structure and Function 12. 1 Discovering Cells