Biology - Chp. 1 Microscopes Flashcards
Who are Hans and Zacharias Janssen
- 1595
- First Compound light Microscope
- 2-lens system, ocular and objective lens
- 20X
Who is Robert Hooke
- 1665
- 3-lens system, ocular, field, objective lens
- 30X
- observed cork, noticed cells
Who is Antoni van Leeuwenhoek
- 1665
- Single-lensed microscope
- 250X
- Observed living cells, bacteria, unicellular protozoa, sperm
- called them “animalcules”
What is Spontaneous Generation
- abiogenesis
- theory that life emerges from non-living matter
Who did experiments to disprove Spontaneous Generation
Francesco Redi (1668)
- air in a jar did not create flies
- flies needed access to jar
Louis Pasteur (1864)
- theory of biogenesis (organisms come from other organisms
- access to the broth allowed for microbe growth
What is Cell theory
- All living matter is made of one or more cells, and the material produced by the cells
- All life functions take place in cells, the smallest unit of life
- All cells are produced form pre-existing cells, through division
Who has contributed to cell theory
Robert Brown (1833)
- single lens microscope saw nuclei in orchid cells’
- recognized importance for cell function
M.J. Schleiden (1838)
- Saw plant cells with nucleus
- Proposed nucleus was responsible for cell development
Schleiden and Schwann (1838)
- all plant/animal cells are composed of cells
- cells are the basic unit of life
Rudolph Virchow (1859)
- All cells are created from pre-existing cells
What factors affect Microscope image quality
Magnification - increasing the size of image
- product of lens magnification (10X x 40X = 400X)
Contrast - distinguish between structures in cell
- cells are colorless with bright light
- Contrast is improved by manipulate light source/using stains
Resolution - distinguish between points close together
- human eye can for points 0.1mm or larger
- Limit of standard light microscope is 0.000 000 6mm
What are Confocal Microscopes
- 1980
- laser concentrates light
- reflection passes through confocal pinhole to reach electronic detector and convert light into image
- All other out of focus light is blocked by edge of pinhole
- image is formed of thin section with high resolution
- images stored in computer, and combined to produce 3-D image
What did the first confocal microscope do
- Use of green fluorescent protein
- glows when exposed to light
- doesn’t kill cell
Who created the first electron microscope
- James Hiller and Albert Prebus
- 1930s
- uses beam of electrons instead of light wave
- image formed by absorption and scattering of electron beam
- focuses through adjustment of electromagnets
- Photos taken though SEM or TEM (micrographs)
- Cannot view live speciems
What are TEM
- transmission electron Microscope
- beam of electrons pass through this tissue
- sensor detects electrons to produce image
- 1 500 000X magnification, 2.5mm resolution
What are SEM
- scanning electron microscope
- specimen are fixed and covered with electron-dense material
- sensors picks up on electrons that bounce off to form image
- 300 000X magnification
- 20 nm resolution
What is Gene Mapping
- map of genomes of various species
- study molecular structure of DNA
What is Cell Communication
- observe molecules in communication
- uses green fluorescent protein technology
