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

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