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Chapter 3 Cells
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History of Cell Theory
•Anton van Leeuwenhoek – first to look at water under a microscope
•Robert Hooke – studied cork under a microscope, first to describe cells
History of Cell Theory cont.
•Matthias Schleiden –determined plants are made of cells
•Theodor Schwann –determined animals are made of cells
All Organisms Are Composed of Cells
Section 3.1
A cell is the smallest unit of life that can function independently.
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Amoeba: © Wim van Egmond/Visuals Unlimited
Cell Theory -Virchow
1. All organisms are composed of one or more cells.
The cell is the basic unit of organization of organisms.
2. All cells come from preexisting cells.
All Organisms Are Composed of Cells
Section 3.1
Most cells are too small to see without a microscope.
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All Organisms Are Composed of Cells
Section 3.1
A transmission electron microscope is a very powerful tool for seeing internal cell structures.
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TEM: © Inga Spence/Visuals Unlimited; Paramecium (TEM): © Microworks Color/Phototake
All Organisms Are Composed of Cells
Section 3.1
A scanning electron microscope is also very powerful and reveals details on cell surfaces.
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SEM: © Inga Spence/Visuals Unlimited; Paramecium (SEM): © Steve Gschmeissner/SPL/Photo Researchers
All Organisms Are Composed of Cells
Section 3.1
Light microscopes are less powerful than electron microscopes. They generate color images of living cells.
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Why Are Cells So Small?
Section 3.1 Figure 3.3
Smaller cells have more surface area relative to their volume. High surface area allows the cell to quickly exchange materials with its surroundings.
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What Features Do Cells Have in Common?
Section 3.1 Figure 3.3
• DNA• RNA• Ribosomes• Proteins• Cytoplasm• Cell membrane
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Amoeba: © Wim van Egmond/Visuals Unlimited
Clicker Question #1
Which cell shape has the highest ratio of surface area to volume?
A.
B.
C.
D.
© 1996 PhotoDisc, Inc./Getty Images/RFCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Clicker Question #1
Which cell shape has the highest ratio of surface area to volume?
A.
B.
C.
D.
© 1996 PhotoDisc, Inc./Getty Images/RF
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
3.1 Mastering Concepts
Describe adaptations that increase the ratio of surface area to volume in cells.
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Different Cell Types Characterize Life’s Three Domains
Section 3.2
Prokaryotes are the most ancient forms of life. They lack a nucleus.
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Different Cell Types Characterize Life’s Three Domains
Section 3.2
Prokaryotes are the most ancient forms of life. They lack a nucleus.
Eukaryotes have cells with a nucleus and other membranous organelles.
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Amoeba: © Wim van Egmond/Visuals Unlimited
Different Cell Types Characterize Life’s Three Domains
Section 3.2 Figure 3.4
Unique features distinguish the Bacteria, Archaea, and Eukarya.
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Two Basic Cell Types
•Prokaryotic cells – cells lacking internal membrane-bound structures
•Most unicellular organisms, such as bacteria, are prokaryotes.
The Anatomy of a Bacterium
Section 3.2 Figure 3.5
Bacteria are prokaryotic. DNA is free in the cytoplasm.
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What They Look Like (cont…)
•All bacteria are basically one of three different shapes:
–Rod- or stick-shaped and called bacilli –Shaped like little balls and called cocci –Helical or Spiral in shape
The Anatomy of an Animal Cell
Section 3.2 Figure 3.6
Animal cells are eukaryotic. They have membrane bounded organelles.
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The Anatomy of a Plant Cell
Section 3.2 Figure 3.7
Plant cells are also eukaryotic, but notice the cell wall and chloroplasts.
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Clicker Question #2
How many of these features does a typical bacterial cell have?
DNA, cell wall, nucleus, ribosomes,cell membrane
A. fiveB. fourC. threeD. twoE. one
© 1996 PhotoDisc, Inc./Getty Images/RF
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Clicker Question #2
How many of these features does a typical bacterial cell have?
DNA, cell wall, nucleus, ribosomes,cell membrane
A. fiveB. fourC. threeD. twoE. one
© 1996 PhotoDisc, Inc./Getty Images/RF
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.