Biology: Patterns in Nature

Topics: Cell, Cell membrane, Blood, Cell wall, Heart, Eukaryote / Pages: 13 (3117 words) / Published: May 23rd, 2012
Chapter 2: Patterns in Nature
1. Cell theory • 1590: Dutch grind glass lens (1st compound microscope)
• 1665: Robert Hooke uses compound m. analysis thin cork slices as filled with air enclosed in boxes (cells) distinct
• 1676: Dutch sees microorganism under microscope from pond water
• 1824: French suggest all organisms composed of cells
• 1827: Robert Brown (Brownian motion) discovered nucleus in plant cell
• 1838: German produced evidence that all organisms made of cells
• 1859: German state cells divide to make new cells
• 1879: German use biological stains to view cells dividing
• The cell theory states that:
– all living organisms are composed of cells
– all cells are produced from pre-existing cells.
• Scientific theory based on evidence from controlled experiment (observation, hypothesis)
• Levels: molecule, organelle, cell, tissue, organ, system and organism

• Light microscope
 objective lens, collects light passing and Ocular lens (second, eye piece)
 Resolution: 0.2 – 0.4 um, can stain to react with specific cell structure
• Electron microscope
 Transmission (transmits electrons) and scanning (electrons bounced off specimen) types (2d & 3d)
 Magnifies 300’000 and resolution 0.0001 um, no colour, vacuum chamber
• Role of technology in development of cell theory
 microscope stopped spontaneous generation
3. Uni/Multicellular • U:
 1 cell (bacteria, protozoa, plankton, yeast)
 Versatile to function as organism, less nutrients/waste
 Metabolism (chemical reaction) complex
• M:
 Animals, plants, fungi
 Metabolism, communication, coordination, transport complex
 If too large, difficult to move substances for metabolism
 Specialised cells
• Cell differentiation:
 Specialised cells (blood, nerve, muscle, skin)
 All contain same genetic material, just how its expressed - active or dormant
 Trigger for DNA change during

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