A Tour of the Cell

1
A Tour of the Cell

• Chapter 6

2
The Cell Theory

• Developed approximately 200 years after Robert
  Hooke observed the first cells in cork with a
  primitive microscope and 150 years after Anton
  van Leeuwenhoek looked at animalcules in pond
  water
• Proposed by Schleiden and Schwann (1838-39) and
  by Virchow (1855)
• 3 Parts
• All living things are made of cells
• The cell is the basic unit of structure and
  function in living things
• All cells come from pre-existing cells

3
Microscopes as Windows to Cells

• Compound Light Microscopes Uses light and lenses
  to magnify objects 1000 times their actual size

4

• Electron Microscopes Use electrons and magnets
  to magnify objects 1,000,000 times their actual
  size
• Scanning Electron Microscope (SEM)- produces
  surface images
• Transmission Electron Microscope (TEM)- produces
  internal images

5

• Scanning Probe Microscopes (SPM) came available
  in the late 1980s and have made atoms visible!

6
Two Major Classes of Cells

• Prokaryotic No nucleus or organelles (1-10mm)
• Ex Bacteria and Archaea
• Eukaryotic Have DNA bound in a nucleus and other
  membrane bound organelles (10-100mm)
• Ex Protists, Fungi, Plants, and Animals

7
Cell Wall

• Present in Plants, Bacteria, Fungi, and Algae
• Made of a rigid polysaccharide called Cellulose
• Porous small molecules and gases easily pass
  through the cell wall

8
Cell (Plasma) Membrane

• All Cells
• Selectively Permeable allows only certain
  substance to pass across the membrane
• Composed of proteins embedded in a phospholipid
  bilayer

9

• Function of proteins embedded in membrane
• membrane-bound enzymes that contribute to
  cellular processes
• cell-to-cell recognition and signaling
• transport proteins provides channels for
  materials to pass