Transcript Cell Theory
Scientific theories and laws Using scientific method a theory is almost never proven. A few theories do become scientific laws (such as the law of gravity) and laws are generally considered to be without exception — though in fact even some laws have been modified over time after further testing found discrepancies. This does not mean theories are not meaningful. For a hypothesis to become a theory, rigorous testing must occur, typically across multiple disciplines by separate groups of scientists. Saying something is “just a theory” is a lay person’s term that has no relationship to science, because in science, a theory is something that is very well supported by observation and experimentation. Theories Cell Theory Evolution Laws Physics, Chemistry, Math- Lots!!!! Biology: Mendelian Inheritance Construct the following timeline in your class notes: Cell Theory Timeline 1665 Hooke observes cork cells 1838 Schleiden concludes that all plants are made of cells 1674 Leeuwenhoek observes living cells 1855 Virchow states that all cells come from other cells 1839 Schwann concludes that all animals are made of cells 1996 Researchers in Scotland clone a sheep from an adult sheep cell The Cell Theory • 1. All organisms are composed of one or more cells. (Schleiden & Schwann 1838-1839) • 2. The cell is the basic unit of life in all living things. (Schleiden & Schwann 1838-1839) • 3. All cells are produced by the division of preexisting cells. (Virchow 1858) • 4. Cells form through spontaneous generation.(was disproven and thrown out) Methods of Cell Study Instrumentation: 1. Compound Light Microscope: Magnifies living and nonliving specimens up to 1500X. 2. Scanning Electron Microscope (SEM): Scans the surface of a specimen with a beam of electrons. Produces three-dimensional images of nonliving specimens magnified more than 100,000X. 3. Transmission Electron Microscope (TEM): Transmits electrons through a thin slice of a specimen. Produces two-dimensional images of nonliving specimens magnified more than 100,000X. Anatomy of a Microscope • Please refer to pg. R8 to help you identify the parts of the microscope. • Complete the first pg. of the packet (both sides) NAME_______________Period:__ Number your paper 1-5 & choose the correct letter for each organelle 1. 2. 3. 4. 5. Mitochondria Cell membrane Cell wall Nucleus Chloroplast a) Protects the cell b) Supplies energy for the cell c) Holds the genetic information of the cell d) Converts solar energy into chemical energy e) Provides rigid support for plant cells Measurement: • The very small size of most cells requires the use of a small unit for measurement. This unit is known as the micrometer ( m ). • One thousand micrometers is equal to one millimeter. Techniques: 1. Wet Mount Preparation 2. Staining Additional Information • The cell contains hereditary information (DNA) which is passed on from cell to cell during cell division. • All cells are basically the same in chemical composition and metabolic activities. • All basic chemical & physiological functions are carried out inside the cells.(movement, digestion, etc.) • Cell activity depends on the activities of sub-cellular structures within the cell(organelles, nucleus, plasma membrane) • Impact of Technology: The improvement of the microscope and microscope techniques throughout the last four centuries (400 years) has allowed scientists to observe cells better and to develop the cell theory. Exit Slip! • Get a workbook from the back cabinet • Read pgs. 37-38 • Answer #1-4 and turn in before you leave