INVESTIGATING CELLS

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INVESTIGATING CELLS

• MICROSCOPES

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THE MICROSCOPIC WORLD OF CELLS

• Cells are the building blocks of all life

• Cells must be tiny for materials to move in and
  out of them fast enough to meet the cells
  metabolic needs

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• If you stacked up 8000 cell membranes, they would
  be only as thick as a page in this book

• Every second, your body produces about 2 million
  red blood cells

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• An electron microscope can visualize objects a
  million times smaller than the head of a pin

• The cells of a whale are about the same size as
  the cells of a mouse

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Microscopes as Windows to Cells

• The light microscope is used by many scientists

• Light passes through the specimen
• Lenses enlarge, or magnify, the image

(a) Light micrograph (LM) of a white blood cell
(stained purple) surrounded by red blood cells
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• Magnification

• An increase in the specimens apparent size
• Resolving power
• The ability of an optical instrument to show two
  objects as separate

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• The electron microscope (EM) uses a beam of
  electrons

• It has a higher resolving power than the light
  microscope

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• The electron microscope can magnify up to 100,000X

Human height
Length of some nerve and muscle cells
Chicken egg
Unaided eye
Frog eggs

• Such power reveals the diverse parts within a cell

Plant and animal cells
Light microscope
Nucleus
Most bacteria
Mitochondrion
Electron microscope
Smallest bacteria
Viruses
Ribosomes
Proteins
Lipids
Small molecules
Atoms
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SEM

• The scanning electron microscope (SEM) is used to
  study the detailed architecture of the surface of
  a cell

(b) Scanning electron micrograph (SEM) of cilia
(above) And a white blood cell
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TEM

• The transmission electron microscope (TEM) is
  useful for exploring the internal structure of a
  cell

(c) Transmission electron micrograph (TEM) of a
white blood cell cilial
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STM

• The scanning tunneling microscope (STM) is a type
  of electron microscope that shows
  three-dimensional images of a sample.

SNOW FLAKE 6 MOLECULES OF WATER Taken from
www.britannica.com/EBchecked/topic-art/281115...
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Types of Microscopes

• Using page 6 of your textbook fill in the
  following table with information about the
  following Microscopes
• TEM Transmission Electron Microscope
• SEM Scanning Electron Microscope
• STM Scanning Tunneling Microscope