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THE FUNDAMENTAL UNIT OF LIFE
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CELLSmallest living unitMost are microscopic
Robert Hooke (mid-1600s)Observed sliver of corkSaw “row of empty boxes”
Coined the term cell
Discovery of Cells
Cells are the basic units of organismsCells can only be observed under microscope
Two basic types of cells:
3Animal Cell Plant Cell
Cell wall
vacuole
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Plant Cell
Made of cellulose which forms very thin fibres
Strong and rigidIn plant cells only
• Cell wall
– Protect and support the enclosed substances (protoplasm)
– Resist entry of excess water into the cell
– Give shape to the cell
• Cell wall
Plant Cell
–A dead layer–Large empty
spaces present between cellulose fibres
freely permeable
• Cell wall
Plant Cell
–Lies immediately against the cell wall
–Made of protein and lipid Selectively permeable
• Cell membrane
Plant Cell
–A living layer–Can control the
movement of materials into and out of the cell
• Cell membrane
Plant Cell
–Jelly-like substance enclosed by cell membrane
–Provide a medium for chemical reactions to take place
• Cytoplasm
Plant Cell
–Contains organelles and granules :•e.g. chloroplast •e.g. mitochondrion
• Cytoplasm
Plant Cell
Organelles
very small size – can only be observed under electron microscope
HAS SPECIFIC FUNCTIONS IN CYTOPLASM
–Contain the green pigment chlorophyll•To trap light energy, to make food by photosynthesis
Plant Cell
• Chloroplast
–Rod shape–For respiration
Plant Cell
• Mitochondrion( mitochondria )
–Starch granules–Oil droplets–Crystals of insoluble wastes
Plant Cell• Non-living
granules
– large central vacuole– Surrounded by
tonoplast– Contains cell sap
• a solution of chemicals (sugars, proteins, mineral salts, wastes, pigments)
Plant Cell
• Vacuole
–Control the normal activities of the cell
–Bounded by a nuclear membrane
–Contains thread-like chromosomes
Plant Cell
• Nucleus
–Each cell has fixed number of chromosomes• Chromosomes carry genes
• Nucleus
Plant Cell
–genes control cell characteristics
DIFFERENCES BETWEEN PLANT CELLS AND ANIMAL CELLS
Animal cells Plant cellsRelatively smaller
in sizeIrregular shape
No cell wall
Relatively larger in size
Regular shapeCell wall present
Vacuole small or absent
Large central vacuoleGlycogen
granules as food store
Starch granules as food store
Nucleus at the centre
Nucleus near cell wall
ULTRASTRUCTURE OF ANIMAL CELL
Ultrastructure of Plant Cell
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WHAT IS
OSMOSIS?
Solution Differences & Cells solvent + solute = solution
HypotonicSolutes in cell more than outsideOutside solvent will flow into cell
IsotonicSolutes equal inside & out of cell
HypertonicSolutes greater outside cellFluid will flow out of cell
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A COMPOUND
MICROSCOPE
and its parts
Eyepiece
Fine adjustmentArm
StageCondenser control knobBase
Body tube
Course adjustment
Iris diaphragm
Revolving nosepiece
Objective
ClipCondenser
Mirror
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