Biology 10

• 7 Characteristics of Life

  • Must be made up of cells
  • Must be able to metabolize
  • Must react to stimuli
  • Must be able to adapt
  • Must be able to grow
  • Must maintain homeostasis
  • Must be able to reproduce
• Units of Life

  • Atoms
  • Molecules
  • Organelles
  • Cells
  • Tissues
  • Organs
  • Systems
  • Organisms
• Janssens


  • Dutch lens makers
  • Developed a microscope with two lenses (eyepiece and objective lens)
  • 1595
• Robert Hook


  • Developed a 3-lens microscope
  • Added light to illuminate the subjects
  • Observed cork under the microscope
  • Coined the term "cells"
  • In 1665
• Antoni Van Leeuenhoek


  • A Dutch businessman
  • Used only a simple single lens microscope
  • Observed bacteria & protozoa
  • Used better microscopes later
• Eyepiece or Ocular lens


  Enlarges the image seen by the objective lens
• Course - Adjustment knob


  Brings the image into focus. Used only with the low power objective lens
• Fine - Adjustment Knob


  Brings image into clearer focus, used with medium and high power objective lens only
• Revolving nosepiece


  Allows you to chose a magnification lens
• Objective Lens


  Magnifies the image. There are low power, med. power & high power objective lenses
• Stage


  Supports the slide
• Stage Clips


  Holds the slide in place
• Diaphragm


  Controls the amount of light reaching the object
• Lamp or Mirror


  Sends light up through the diaphragm to the object
• Arm


  Supports the microscope
• Base


  Supports the microscope
• Tube


  Holds the eyepiece and the objective lens at the correct distance from one another
• Magnification


  The degree of enlargement of an image
• Total Magnification


  The product of the ocular lens and objective lens
• Field of View Diameter


  The diameter of the area seen through the microscope
• Scale


  A ratio used to compare actual size of specimen to the drawing size of specimen
• Spontaneous Generation

  1. Without the observations of the microscopic world, our understanding of life was limited to what we observed with the naked eye

  2. For over 1000 years, the idea of spontaneous generation was a strongly held on

  3. Given the right conditions, life would just spontaneously appear
• Redi’s Experiment

  1. Francesco Redi questioned the belief that maggots spontaneously appeared from raw meat

  2. Used 3 flasks of red meat: one open to flies, one covered in gauze, one sealed
• Needham's & Spallanzani's Experiment


  1. There was a common belief that a life-force in air caused spontaneous generation of micro-organisms in broth

  2. Derived from observation that, even though a broth was boiled and microorganisms were killed, sealed broth still grew micro-organisms (Needham's experiment)

  3. Spallanzani suggested it was micro-organisms in the air

  4. Drew off air from broth and sealed - nothing grew

  5. Suggested then that needed air for spontaneous generation
• Pasteur’s Experiment

  1. Designed as an experiment to disprove spontaneous generation

  2. Designed a system of flasks that prevented particles from coming in contact with the broth

  3. Used controlled, manipulated, and responding variables

  4. Controlled - broth type, flask type, light, and temperature

  5. Manipulated - access of dust to flask

  6. Responding - ability to grow mould

  7. Did not observe formation of mould unless liquid came in contact with particles
• Cell theory began forming with improved lens technology
• Robert Brown identified the nucleus in orchid cells
• Schleiden and Schwann proposed cell theory based on their observations
• Schleiden


  A botanist who studied plants and observed that plants were made of cells
• Schleiden


  Stated that the nucleus was the structure responsible for the development of the remainder of the cell
• Schwann


  Studied animal physiology and found a lot of similarities in plant and animal cells
• Schwann

  Proposed that both plants and animals are made up of cells
• Virchow further added to cell theory and suggested that all cells arise only from pre-existing cells
• Cell theory


  All living things made up of 1 or more cells and materials produced from these cells
• Cell theory

  All life functions within cells: smallest unit of life
• Cell theory

  Cells produced from other cells (cell division)
• Imaging Technology

  Light Microscope magnifies cells using a curved lens and a light source
• Most cells and structures are pale or transparent, making it difficult to see details
• To improve the image, contrast and resolution can be enhanced
• Contrast


  Alters color or shade of parts to make the image more visible