Biology: Patterns in Nature

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Biology: Patterns in Nature

By | May 2012
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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

2.
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
ASK IF PAGES 69-70 NEED SUMMARY AND SUMMARISE ON DIFFERENT PAPER 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 dif. from...

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