Transcript Biology 120 Chapter 3 Cells

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
Tonicity Experiment
2 % sucrose
10% sucrose
water
Fig. 5-17a, 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.
Fig. 5-17 (b-d), p. 89
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”