+ chapter 2, section 3 discovering cells. + an overview of cells cells: the basic units of structure...
TRANSCRIPT
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Chapter 2, Section 3
Discovering Cells
+An Overview of Cells
Cells: the basic units of structure and function in
living things
Cells and StructureHow cells are put together and the shape that forms
Cells and FunctionObtaining oxygen, getting rid of wastes, obtaining
food, and growing
+First Observations of Cells 1590
The invention of the microscope made it possible for people to discover and learn about cells
Microscope: an instrument that makes small objects look larger SIMPLE MICROSCOPE: one
lens COMPOUND MICROSCOPE:
more than one lens
+Robert Hooke
One of the first people to observe cells
Built his own compound microscope
Used this microscope to observe thin slice of cork Looked like tiny rectangular rooms, called
them cells meaning “small rooms”
+Anton van Leeuwenhoek
About the same time as Hooke
Built a simple microscope
Used this microscope to observe lake water, scrapings from teeth and gums, and water from rain gutters He noticed that many of the things
he observed were ONE-CELLED
He called the moving organisms he saw ANIMALCULES (“little animals”)
+Development of the Cell TheoryThree scientists worked together…
Schleiden Concluded all plants are made of cells
Schwann Concluded that all animals are also made of cells
THEREFORE, all living things are made up of cells
Virchow New cells are formed only
from cells that already exist “All cells come from cells”
+The Cell Theory
The cell theory is a widely accepted explanation of the relationship between cells and living things
1. All living things are composed of cells
2. Cells are the basic units of structure and function in living things
3. All cells are produced from other cells
+ Magnification and Lenses
Lenses in light microscopes magnify an object by BENDING the light that passes through them
Convex lens: magnifying glass and hand lenses Middle of lens is thicker Outside of lens is thinner
+Compound Microscope Magnification
Lenses of a LIGHT microscope… Light passes through specimen Then through two lenses
1st lens near specimen magnifies object 2nd lens near the eye further enlarges object
Example: One lens makes an object 10 times larger,
second lens makes an object 40 times larger TOTAL: 10 X 40 = 400
+Resolution
Being able to clearly distinguish the individual parts of an object
Or…sharpness of an image
+Electron Microscope
Electron microscope uses a beam of electrons instead of light to produce a magnified image
The resolution is much better than the resolution of a light microscope