The Building Blocks of Life

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Cells

• The Building Blocks of Life

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Cells are Us
A person contains about 100 trillion cells.
Thats 100,000,000,000,000 or 1 x 1014 cells.
There are about 200 different cell types in
mammals (one of us).
Cells are teeny, tiny, measuring on average about
0.002 cm (20 um) across. Thats about 1250 cells,
shoulder-to-shoulder per inch.
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Why Study Cell Biology?
The key to every biological problem must finally
be sought in the cell, for every living organism
is, or at some time has been, a cell. E.B.
Wilson, 1925
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The Cell Theory (review)
The Cell Theory (proposed independently in 1838
and 1839) is a cornerstone of biology.

• Cells are the basic unit of life

• All Cells arise from previously existing cells

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TODAY

• Cell Structure and Function 
• What are the common features of all cells?
• What is the difference between prokaryotic and
  eukaryotic cells?

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Two Types of Cells
Two Fundamentally Different Cell Architectures
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Prokaryotic cells

• have no nucleus or organelles enclosed within
  membranes.
• All species in the domains Archaea and Eubacteria
  have prokaryotic cells.

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Eukaryotic cells

• have a nucleus and organelles that are surrounded
  by membranes.
• Each organelle does a specific cell function.
• All species in the Eukaryota domain (protists,
  fungi, plants, and animals) have eukaryotic
  cells. Individual protists have only one cell,
  while plants and animals can have trillions of
  cells.

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Prokaryotes vs. Eukaryotes
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Size comparison??
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• 1. A few types of cells are large enough to be
  seen by the unaided eye. 
• 2. Most cells are visible only with a microscope.

• The Female Egg is the largest cell in the body,
  and can be seen without the aid of a microscope.

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PROKARYOTES vs. EUKARYOTES Differences
(Location)
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Similarities Common Features of ALL CELLS!
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The common features of prokaryotic and eukaryotic
cells are

• 1. DNA2. Plasma membrane (a.k.a. cell
  membrane)
• 3. Cytoplasm
• 4. Ribosomes

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What Do Those Parts Do?