Biology: Patterns in Nature

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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 chemicals in immediate environment
4. Cell organelles

Little organs in cell, roles to perform to make cell work bound by membrane •Found in cytoplasm (fluid between cell membrane and nuclear membrane) (Protoplasm) •Nucleus/Nucleolus
Deoxyribonucleic Acid (DNA – complex chemical) & Ribonucleic (RNA-nucleic acid) Molecules form chemical code top determine structure, control DNA present in chromosomes. Nucleolus producers ribosome RNA •Plastids (Plants)

Leucoplasts: store nutrients (starch/colourless)
Chromoplasts: orange/yellow/red pigments (giving colour) Chloroplasts: contain chlorophyll ( in grana)
Mitochondria
Have internal membranes (cristae) (fold at right angles for more SA for more reactions - cellular respiration Respiration: breakdown of glucose & energy into adenosine triphosphate (ATP e.g. m=muscle cell contraction) •Endoplasmic Reticulum

System of membranes – channels/tubules with chemical activity Some extensions of membrane, transport nutrients/waste
Rough: ribosome’s on surfaces
Smooth: immature & lacks ribosome’s on membrane

Ribosome
Smallest organelles, attached to E.R
Used for protein synthesis, no membrane – composed of protein or nucleic acid RNA (chemical molecules •Golgi Bodies
Specialised area of E.R, forms vesicles (sacs), break off & transport Synthesised proteins stored short then transported (e.g. p 75) •Lysomes
Small vesicles containing enzymes attacking foreign protein From Golgi to phagocytes (immune) destroying bacteria
Vacuoles
Fluid filled spaces around membrane supporting cell
water in plants to support
Cell membrane
Surrounds/protects cell, controls transport, surface for reactions •Cell wall
Cellulose made, allow transport (plasmodesmata)
Rigid with support, allow water for turgid
Cytoskeleton
Microtubes, microfilaments supporting cytoplasm and organelles (eucary) •Prokaryotic: primitive, no nucleus/organelles, unicellular...
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