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Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 Theories of Life: An Introduction to Biology Biology is the study of life and living organisms Nov 30­11:04 AM The scientific definition of what const...

Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 Theories of Life: An Introduction to Biology Biology is the study of life and living organisms Nov 30­11:04 AM The scientific definition of what constitutes life has changed over time, but today it is agreed upon by scientists that all living organisms must have five characteristics in order to be considered alive: 1. They need energy (usually in some sort of food) Nov 30­11:04 AM 1 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 2. They produce waste material Nov 30­11:04 AM 3. They respond and adapt to the environment Nov 30­11:04 AM 2 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 4. They reproduce Nov 30­11:04 AM 5. They grow Nov 30­11:04 AM 3 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 Aristotle (384­322 B.C.) devised a theory of the origin of life based on observations o He observed the sexual and asexual reproduction of some organisms and noted that life often comes from other living organisms Nov 30­11:04 AM o Some living organisms, particularly organisms that were very small, seemed to reproduce from non­living material (e.g. maggots appearing in meat, mould on food, etc.). This led Aristotle and others to hypothesize that under certain conditions, life can come from non­living matter. Nov 30­11:04 AM 4 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 o The theory that life came from non­life was referred to as spontaneous generation or abiogenesis. Nov 30­11:04 AM Since that time, many scientists questioned this theory and attempted to disprove it. Read the studies of Francesco Redi and Louis Pasteur on pages 258­259 in your text books. In your notes, summarize their findings. Your notes must include the following: o The setup of their experiment o The control group o The manipulated and responding variables (what they changed and what they noticed) o Their findings Nov 30­11:04 AM 5 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 Redi's Experiment Nov 30­11:04 AM Pasteur's Experiment Nov 30­11:04 AM 6 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 This discovery that life only comes from preexisting life is called the theory of biogenesis Nov 30­11:04 AM Cell Theory and the Microscope The invention of the microscope made it possible for scientists to see objects otherwise unseen and allow them to answer many questions about the structure of organisms o One such discovery was that living organisms are composed of small units called cells. Over time, new technologies and new discoveries led to the development of a theory on cells Nov 30­11:04 AM 7 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 Robert Hooke Robert Hooke was a 17th Century scientist from England He examined slices of cork under the microscope and noticed that the cork was made up of several tiny rooms o These rooms he called “cells” Nov 29­7:33 AM http://dictionary.reference.com/browse/animalcule?s=t Anton van Leeuwenhoek Leeuwenhoek, a Dutch merchant, studied cells with a more powerful microscope (500x magnification as opposed to Hooke’s 30x) several years after Hooke’s discoveries o He studied scrapings from his teeth and discovered many microscopic organisms he called “animalcules , which later were identified as single­ celled organisms Nov 29­7:35 AM 8 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 Schleiden and Schwann Two German scientists in the 1800s who concluded that all plants and animals were made up of cells Also concluded that new cells originated from nuclei o They eventually concluded that all living organisms are made up of cells Nov 29­7:36 AM Rudolf Virchow German physicist who concluded that cells divide to produce more cells. This corrected the misconception of Schleiden and Schwann that cells formed from non­living materials o “Where a cell exists, there must have been a pre­ existing cell.” Nov 29­7:39 AM 9 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 Cell Theory The findings of these scientists helped establish the cell theory The Cell Theory is comprised of three main conclusions: 1. All organisms are composed of one or more cells 2. The cell is the smallest functional unit of life 3. All cells are produced from other cells Nov 29­7:41 AM Pod http://www.youtube.com/watch?v=jCMQ3SEbrDI TED Talk http://www.youtube.com/watch?v=4OpBylwH9DU May 7­5:40 PM 10 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 Please complete CYU questions 1, 2, 3, and 6 on page 265. Nov 29­7:42 AM Do Now Problem: Is fire alive? Use your knowledge of living things to argue why, or why not. Dec 1­11:46 AM 11 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 Topic 1C- The Microscopes May 10­8:26 AM Early Microscopes A simple microscopes had a single lense. These primitive instruments could magnify ten to twenty times. The first known compound microscope was developed in 1590 by the Janssen brothers, two Dutch eyeglass makers. The compound microscope had two lenses, one mounted at each end of a tube. May 12­10:46 AM 12 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 The Modern Compound Microscopes: Modern microscopes use ordinary light to produce an image, they are called light microscopes. In a light microscope, light passes through a cell or other thin object and then through glass lenses. The lenses bend the light in such a way that the image of the specimen is magnified as it is projected into the eye. If an object under a light microscope is too thick for light to pass through, the object cannot be seen. May 12­10:47 AM A modern light microscope contains several lenses. 1. The objective lens magnifies the object being viewed. (Most high school microscopes have objective lenses that magnify 4, 10 or 40 times). 2. A second lens called the ocular lens then magnifies the image produced by the objective lens. (The ocular lens or the eyepiece is the part of the microscope that the observer looks through and usually has a magnification of 10X). The total magnification of microscope is then calculated by multiplying the magnification power of the two lenses. o Therefore the most commonly used microscopes magnify objects from 40 to 400 times. May 12­10:49 AM 13 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 The nature of light limits how much a compound light microscope can enlarge an image or magnify an object clearly. When light passes through each set of lenses, the light rays are spread apart. The greater the magnification, the greater the spreading or bending of the rays. The more the light is spread, the poorer the resolution of the image. Resolution is the microscopes ability to deliver a visible image with clear detail. May 12­10:49 AM Use the following parts to label the diagram: 12. May 12­10:50 AM 14 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 1. May 13­7:02 PM 10. May 13­7:02 PM 15 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 13 May 13­7:02 PM 6 May 13­7:02 PM 16 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 3 May 13­7:04 PM The Electron Microscope During the 1930s, two Canadian scientists developed a much more powerful microscope called the transmission electron microscope (TEM). It uses an electron beam instead of light to produce an image. Electromagnets focus the electron beam replacing the glass lenses in a light microscope. The image is produced on a special screen or can be viewed via a photograph called a micrograph. An electron microscope can magnify biological materials up to about 100 000 times and some non­biological materials up to 1 000 000 times. The scanning electron microscope (SEM). In the scanning electron microscope electrons do not pass through the object, instead they are reflected off the surface of the object. May 12­10:50 AM 17 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 To be seen under a transmission electron microscope, biological material must be prepared in a special way. The specimen is dried, sliced, mounted and coated with a very thin metallic film: then placed in a vacuum chamber to be bombarded with a fine beam of electrons. One disadvantage of the electron microscope is that this preparation kills the cells. Specimens cannot be alive while being studied. This is a dilemma for biologists. They can look at living organisms and cells at low magnification or they can look at dead cells at high magnification but they cannot view living cells at high magnification. Even though you can view living cells under light microscopes, stains must be used to see some structures. Different cell structures absorb different kinds and amounts of stain making them visible. Unfortunately, stains also kill the cells. Dec 1­9:56 AM May 12­10:51 AM 18 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 http://www.youtube.com/watch?v=lrXMIghANbg http://www.youtube.com/watch?v=fToTFjwUc5M TEM & Scan Microscope May 12­11:02 AM http://www.youtube.com/watch?v=9nUseN_E­l0 Parts of Compound Microscope May 13­8:41 AM 19 Topic 1A_B&C ­ Theories of Life & Cells.notebook December 09, 2015 Homework: Complete pg. 8 & 14 in your note package May 13­7:14 PM 20