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It’s a Cellular World Unit 2: Cells

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1 It’s a Cellular World Unit 2: Cells
Chapter 7: Cell Structure and Function Section 7-1 Life is Cellular Text- pages

2 Vocabulary Cell Cell theory Nucleus Eukaryote Prokaryote

3 Objectives SWBAT explain how microscopes came into use and the early observations that were made by scientists. SWBAT describe the three steps of the Cell Theory. SWBAT describe some modern microscope techniques used to look at cells and their parts. SWBAT explain how cells are classified. SWBAT describe the differences between prokaryotes and eukaryotes.

4 Discovering the Cell Mid 1600’s: scientists began to use microscopes to observe living things. 1665: Robert Hooke (England) compound scope 1674: Anton van Leeuwenhoek (Holland) single lens scope.

5 Cell Theory Cell Theory states…
1) All living things are composed of cells. 2) Cells are the basic unit of structure and function in living things. 3) New cells are produced from existing cells.

6 Exploring the Cell Today
Today’s researchers use microscopes and techniques that are much more powerful than those of early scientists. Examples: fluorescent labeling, light microscopes, 3-D imaging using electron microscopes

7 Modern Techniques 3-D imaging Fluorescent Labeling Light Microscopes

8 Electron Microscopes SEM : Scanning Electron Microscope
Scanning a pencil-like beam of electrons over the surface of an object. Produce a 3-d image TEM : Transmission Electron Microscope The transmission electron microscope (TEM) operates on the same basic principles as the light microscope but uses electrons instead of light.

9 TEM resource SEM resources
Pictures From The TEM SEM resources David Scharf: Home Pictures From The SEM

10 Classifying Cells Variety of shapes and sizes. Typical cell 5- 50 µm.
2 common characteristics: Surrounded by barrier- cell membrane At some point in the cell lifespan they contain the molecule that carries biological information- DNA.

11 How small is a micrometer (um)?
1 micrometer (um) is one millionth of a meter 1/1,000,000 m or 1 x 10-6

12 Cell Shapes

13 Classifying Cells cont’d
2 categories of cells- depend upon whether they contain a nucleus. Eukaryotes: contain nuclei Prokaryotes: no nucleus Nucleus: large membrane-enclosed structure that contains cell’s genetic material (nucleic acids) in the form of DNA. Controls many of the cell’s activities.


15 Prokaryotes Smaller and simpler than eukaryotes. No nucleus.
Some contain organelles. Carry out every activity associated with living things. Grow, reproduce, respond to environment, glide, and swim Example: Bacteria


17 Eukaryotes Larger and more complex than prokaryotes.
Contain dozens of organelles. Highly specialized Contain nucleus Single celled or multi-cellular. Examples: plants, animals, fungi, and protists.




21 Review Questions What are the 3 statements that make up the cell theory? What’s the difference between prokaryotes and eukaryotes? Do bacterial cells contain nuclei?

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