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Cells
Chapter 3
Cells
The Cell Theory Emerges
Modern cell theory• All organisms consists of one or more cells• Each new cell arises from division of another,
preexisting cell• A cell is the smallest unit with the properties of life• Each cell passes its hereditary material to its
offspring
All Cells Have:
1. Plasma membrane• Controls substances passing in and out of the cell
2. DNA
3. Cytoplasm• A semifluid mixture containing cell components
4. Ribosomes
Prokaryotic Cell
Note what it is lacking
Eukaryotic Cell
Fig. 5-8 (a-c), p. 83
Fig. 5-8 (d-e), p. 83
Osmosis
Osmosis• The movement of water down its concentration
gradient – through a selectively permeable membrane from a region of lower solute concentration to a region of higher solute concentration
Osmosis
Fig. 5-17a, p. 89
Tonicity Experiment
2 % sucrose 10% sucrose water
Fig. 5-17 (b-d), p. 89
B Red blood cells in an isotonic solution do not change in volume.
C Red blood cells in a hypertonic solution shrivel because water diffuses out of them.
D Red blood cells in a hypotonic solution swell because water diffuses into them.
Hydrostatic Pressure in Plants
Are paramecium’s surroundings hypotonic, hypertonic, or isotonic?
Osmoregulation
Osmoregulation
Woman Dies of Water Intoxication-2007“Hold Your Wee for a Wii Contest”